android源码浅析--AlertController

在android源码解析--AlertDialog及AlertDialog.Builder这篇文章中，讲到在Builder中功能的实现主要是调用AlertController实现的，而该类是android内部类，在package com.android.internal.app包中，不能在Eclipse中通过ctrl键来跟踪源码，所以使用Source Insight软件打开该软件源码，查看一下。

跟以前一样，先看下AlertController类中的私有成员变量：

private final Context mContext;
    private final DialogInterface mDialogInterface;
    private final Window mWindow;
    
    private CharSequence mTitle;

    private CharSequence mMessage;

    private ListView mListView;
    
    private View mView;

    private int mViewSpacingLeft;
    
    private int mViewSpacingTop;
    
    private int mViewSpacingRight;
    
    private int mViewSpacingBottom;
    
    private boolean mViewSpacingSpecified = false;
    
    private Button mButtonPositive;

    private CharSequence mButtonPositiveText;

    private Message mButtonPositiveMessage;

    private Button mButtonNegative;

    private CharSequence mButtonNegativeText;

    private Message mButtonNegativeMessage;

    private Button mButtonNeutral;

    private CharSequence mButtonNeutralText;

    private Message mButtonNeutralMessage;

    private ScrollView mScrollView;
    
    private int mIconId = -1;
    
    private Drawable mIcon;
    
    private ImageView mIconView;
    
    private TextView mTitleView;

    private TextView mMessageView;

    private View mCustomTitleView;
    
    private boolean mForceInverseBackground;
    
    private ListAdapter mAdapter;
    
    private int mCheckedItem = -1;

    private int mAlertDialogLayout;
    private int mListLayout;
    private int mMultiChoiceItemLayout;
    private int mSingleChoiceItemLayout;
    private int mListItemLayout;

    private Handler mHandler;

mAlertDialogLayout：AlertDialog布局
mListLayout：List布局
mMultiChoiceItemLayout：多选布局
mSingleChoiceItemLayout：单选布局
mListItemLayout：listItem布局

接着下面是一个自定义的View OnClickListener事件，其目的把点击对象的信息发送到对应的线程（UI线程）：

View.OnClickListener mButtonHandler = new View.OnClickListener() {
        public void onClick(View v) {
            Message m = null;
            if (v == mButtonPositive && mButtonPositiveMessage != null) {
                m = Message.obtain(mButtonPositiveMessage);
            } else if (v == mButtonNegative && mButtonNegativeMessage != null) {
                m = Message.obtain(mButtonNegativeMessage);
            } else if (v == mButtonNeutral && mButtonNeutralMessage != null) {
                m = Message.obtain(mButtonNeutralMessage);
            }
            if (m != null) {
                m.sendToTarget();
            }

            // Post a message so we dismiss after the above handlers are executed
            mHandler.obtainMessage(ButtonHandler.MSG_DISMISS_DIALOG, mDialogInterface)
                    .sendToTarget();
        }
    };

前面获取点击传递的Message，发送到目标线程（UI线程），然后再发送一个Message，通知UI线程关闭此对话框。里面使用到的ButtonHandler.MSG_DISMISS_DIALOG，就在下面代码中定义（关于Message和Handler发送消息，请参看前面博文）。

private static final class ButtonHandler extends Handler {
        // Button clicks have Message.what as the BUTTON{1,2,3} constant
        private static final int MSG_DISMISS_DIALOG = 1;
        
        private WeakReference<DialogInterface> mDialog;

        public ButtonHandler(DialogInterface dialog) {
            mDialog = new WeakReference<DialogInterface>(dialog);
        }

        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                
                case DialogInterface.BUTTON_POSITIVE:
                case DialogInterface.BUTTON_NEGATIVE:
                case DialogInterface.BUTTON_NEUTRAL:
                    ((DialogInterface.OnClickListener) msg.obj).onClick(mDialog.get(), msg.what);
                    break;
                    
                case MSG_DISMISS_DIALOG:
                    ((DialogInterface) msg.obj).dismiss();
            }
        }
    }

看一下逻辑的处理，如果传进来的Message的信息是DialogInterface.BUTTON_POSITIVE、DialogInterface.BUTTON_NEGATIVE、DialogInterface.BUTTON_NEUTRAL响应其DialogInterface.OnClickListener中的OnClick事件。如果是MSG_DISMISS_DIALOG，就关闭其对话框窗口。

下面是一个判断对话框单个Button是否应居中：

private static boolean shouldCenterSingleButton(Context context) {
        TypedValue outValue = new TypedValue();
        context.getTheme().resolveAttribute(com.android.internal.R.attr.alertDialogCenterButtons,
                outValue, true);
        return outValue.data != 0;
    }

再往下是其构造函数：

 public AlertController(Context context, DialogInterface di, Window window) {
        mContext = context;
        mDialogInterface = di;
        mWindow = window;
        mHandler = new ButtonHandler(di);

        TypedArray a = context.obtainStyledAttributes(null,
                com.android.internal.R.styleable.AlertDialog,
                com.android.internal.R.attr.alertDialogStyle, 0);

        mAlertDialogLayout = a.getResourceId(com.android.internal.R.styleable.AlertDialog_layout,
                com.android.internal.R.layout.alert_dialog);
        mListLayout = a.getResourceId(
                com.android.internal.R.styleable.AlertDialog_listLayout,
                com.android.internal.R.layout.select_dialog);
        mMultiChoiceItemLayout = a.getResourceId(
                com.android.internal.R.styleable.AlertDialog_multiChoiceItemLayout,
                com.android.internal.R.layout.select_dialog_multichoice);
        mSingleChoiceItemLayout = a.getResourceId(
                com.android.internal.R.styleable.AlertDialog_singleChoiceItemLayout,
                com.android.internal.R.layout.select_dialog_singlechoice);
        mListItemLayout = a.getResourceId(
                com.android.internal.R.styleable.AlertDialog_listItemLayout,
                com.android.internal.R.layout.select_dialog_item);

        a.recycle();
    }

初始化上面提到的私有变量（关于TypeArray的用法，参考：http://blog.csdn.net/aomandeshangxiao/article/details/7449973）。

下面的静态方法是判断View是否支持输入：

static boolean canTextInput(View v) {
        if (v.onCheckIsTextEditor()) {
            return true;
        }
        
        if (!(v instanceof ViewGroup)) {
            return false;
        }
        
        ViewGroup vg = (ViewGroup)v;
        int i = vg.getChildCount();
        while (i > 0) {
            i--;
            v = vg.getChildAt(i);
            if (canTextInput(v)) {
                return true;
            }
        }
        
        return false;
    }

是文本编辑控件就返回true，然后弹出软键盘。

下面方法，插入内容：

public void installContent() {
        /* We use a custom title so never request a window title */
    	//无标题模式
        mWindow.requestFeature(Window.FEATURE_NO_TITLE);
        
        //如果视图为空，或者不是可编辑控件，那么就自动隐藏掉软键盘
        if (mView == null || !canTextInput(mView)) {
            mWindow.setFlags(WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM,
                    WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM);
        }
        //设置系统AlertDialog为视图
        mWindow.setContentView(mAlertDialogLayout);
        setupView();
    }

看一下其调用的setupView方法（384行）：

private void setupView() {
        LinearLayout contentPanel = (LinearLayout) mWindow.findViewById(R.id.contentPanel);
        setupContent(contentPanel);
        boolean hasButtons = setupButtons();
        
        LinearLayout topPanel = (LinearLayout) mWindow.findViewById(R.id.topPanel);
        TypedArray a = mContext.obtainStyledAttributes(
                null, com.android.internal.R.styleable.AlertDialog, com.android.internal.R.attr.alertDialogStyle, 0);
        boolean hasTitle = setupTitle(topPanel);
            
        View buttonPanel = mWindow.findViewById(R.id.buttonPanel);
        if (!hasButtons) {
            buttonPanel.setVisibility(View.GONE);
            mWindow.setCloseOnTouchOutsideIfNotSet(true);
        }

        FrameLayout customPanel = null;
        if (mView != null) {
            customPanel = (FrameLayout) mWindow.findViewById(R.id.customPanel);
            FrameLayout custom = (FrameLayout) mWindow.findViewById(R.id.custom);
            custom.addView(mView, new LayoutParams(MATCH_PARENT, MATCH_PARENT));
            if (mViewSpacingSpecified) {
                custom.setPadding(mViewSpacingLeft, mViewSpacingTop, mViewSpacingRight,
                        mViewSpacingBottom);
            }
            if (mListView != null) {
                ((LinearLayout.LayoutParams) customPanel.getLayoutParams()).weight = 0;
            }
        } else {
            mWindow.findViewById(R.id.customPanel).setVisibility(View.GONE);
        }
        
        /* Only display the divider if we have a title and a 
         * custom view or a message.
         */
        if (hasTitle) {
            View divider = null;
            if (mMessage != null || mView != null || mListView != null) {
                divider = mWindow.findViewById(R.id.titleDivider);
            } else {
                divider = mWindow.findViewById(R.id.titleDividerTop);
            }

            if (divider != null) {
                divider.setVisibility(View.VISIBLE);
            }
        }
        
        setBackground(topPanel, contentPanel, customPanel, hasButtons, a, hasTitle, buttonPanel);
        a.recycle();
    }

其中又相继调用了setupContent()、setupTitle()、setBackground()、setupButtons()等方法，分别设置内容部分、标题部分、背景、底部等。

先看下setupContent()方法：

private void setupContent(LinearLayout contentPanel) {
        mScrollView = (ScrollView) mWindow.findViewById(R.id.scrollView);
        mScrollView.setFocusable(false);
        
        // Special case for users that only want to display a String
        mMessageView = (TextView) mWindow.findViewById(R.id.message);
        if (mMessageView == null) {
            return;
        }
        
        if (mMessage != null) {
            mMessageView.setText(mMessage);
        } else {
            mMessageView.setVisibility(View.GONE);
            mScrollView.removeView(mMessageView);
            
            if (mListView != null) {
                contentPanel.removeView(mWindow.findViewById(R.id.scrollView));
                contentPanel.addView(mListView,
                        new LinearLayout.LayoutParams(MATCH_PARENT, MATCH_PARENT));
                contentPanel.setLayoutParams(new LinearLayout.LayoutParams(MATCH_PARENT, 0, 1.0f));
            } else {
                contentPanel.setVisibility(View.GONE);
            }
        }
    }

设置对话框中间显示view内容。

设置底部：

private boolean setupButtons() {
        int BIT_BUTTON_POSITIVE = 1;
        int BIT_BUTTON_NEGATIVE = 2;
        int BIT_BUTTON_NEUTRAL = 4;
        int whichButtons = 0;
        mButtonPositive = (Button) mWindow.findViewById(R.id.button1);
        mButtonPositive.setOnClickListener(mButtonHandler);

        if (TextUtils.isEmpty(mButtonPositiveText)) {
            mButtonPositive.setVisibility(View.GONE);
        } else {
            mButtonPositive.setText(mButtonPositiveText);
            mButtonPositive.setVisibility(View.VISIBLE);
            whichButtons = whichButtons | BIT_BUTTON_POSITIVE;
        }

        mButtonNegative = (Button) mWindow.findViewById(R.id.button2);
        mButtonNegative.setOnClickListener(mButtonHandler);

        if (TextUtils.isEmpty(mButtonNegativeText)) {
            mButtonNegative.setVisibility(View.GONE);
        } else {
            mButtonNegative.setText(mButtonNegativeText);
            mButtonNegative.setVisibility(View.VISIBLE);

            whichButtons = whichButtons | BIT_BUTTON_NEGATIVE;
        }

        mButtonNeutral = (Button) mWindow.findViewById(R.id.button3);
        mButtonNeutral.setOnClickListener(mButtonHandler);

        if (TextUtils.isEmpty(mButtonNeutralText)) {
            mButtonNeutral.setVisibility(View.GONE);
        } else {
            mButtonNeutral.setText(mButtonNeutralText);
            mButtonNeutral.setVisibility(View.VISIBLE);

            whichButtons = whichButtons | BIT_BUTTON_NEUTRAL;
        }

        if (shouldCenterSingleButton(mContext)) {
            /*
             * If we only have 1 button it should be centered on the layout and
             * expand to fill 50% of the available space.
             */
            if (whichButtons == BIT_BUTTON_POSITIVE) {
                centerButton(mButtonPositive);
            } else if (whichButtons == BIT_BUTTON_NEGATIVE) {
                centerButton(mButtonNeutral);
            } else if (whichButtons == BIT_BUTTON_NEUTRAL) {
                centerButton(mButtonNeutral);
            }
        }
        
        return whichButtons != 0;
    }

设置底部主要是对话框按钮这一部分区域的设置，里面调用了centerButton方法：

private void centerButton(Button button) {
        LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) button.getLayoutParams();
        params.gravity = Gravity.CENTER_HORIZONTAL;
        params.weight = 0.5f;
        button.setLayoutParams(params);
        View leftSpacer = mWindow.findViewById(R.id.leftSpacer);
        if (leftSpacer != null) {
            leftSpacer.setVisibility(View.VISIBLE);
        }
        View rightSpacer = mWindow.findViewById(R.id.rightSpacer);
        if (rightSpacer != null) {
            rightSpacer.setVisibility(View.VISIBLE);
        }
    }

设置button水平居中。在setupButton代码注释里面也说了：如果只有一个button，设置其居中并占据可用区域的一半。

再来看一下setupTitle()：

 private boolean setupTitle(LinearLayout topPanel) {
        boolean hasTitle = true;
        
        if (mCustomTitleView != null) {
            // Add the custom title view directly to the topPanel layout
            LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
                    LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
            
            topPanel.addView(mCustomTitleView, 0, lp);
            
            // Hide the title template
            View titleTemplate = mWindow.findViewById(R.id.title_template);
            titleTemplate.setVisibility(View.GONE);
        } else {
            final boolean hasTextTitle = !TextUtils.isEmpty(mTitle);
            
            mIconView = (ImageView) mWindow.findViewById(R.id.icon);
            if (hasTextTitle) {
                /* Display the title if a title is supplied, else hide it */
                mTitleView = (TextView) mWindow.findViewById(R.id.alertTitle);

                mTitleView.setText(mTitle);
                
                /* Do this last so that if the user has supplied any
                 * icons we use them instead of the default ones. If the
                 * user has specified 0 then make it disappear.
                 */
                if (mIconId > 0) {
                    mIconView.setImageResource(mIconId);
                } else if (mIcon != null) {
                    mIconView.setImageDrawable(mIcon);
                } else if (mIconId == 0) {
                    
                    /* Apply the padding from the icon to ensure the
                     * title is aligned correctly.
                     */
                    mTitleView.setPadding(mIconView.getPaddingLeft(),
                            mIconView.getPaddingTop(),
                            mIconView.getPaddingRight(),
                            mIconView.getPaddingBottom());
                    mIconView.setVisibility(View.GONE);
                }
            } else {
                
                // Hide the title template
                View titleTemplate = mWindow.findViewById(R.id.title_template);
                titleTemplate.setVisibility(View.GONE);
                mIconView.setVisibility(View.GONE);
                topPanel.setVisibility(View.GONE);
                hasTitle = false;
            }
        }
        return hasTitle;
    }

首先，如果设置了自定义的顶部视图，就是用自定义视图，并隐藏标题模板视图。否则使用默认视图设置其顶部显示标题文字，图片的内容，如果没有标题文字，也隐藏标题模板视图。

后面是setBackground():

private void setBackground(LinearLayout topPanel, LinearLayout contentPanel,
            View customPanel, boolean hasButtons, TypedArray a, boolean hasTitle, 
            View buttonPanel) {
        
        /* Get all the different background required */
        int fullDark = a.getResourceId(
                R.styleable.AlertDialog_fullDark, R.drawable.popup_full_dark);
        int topDark = a.getResourceId(
                R.styleable.AlertDialog_topDark, R.drawable.popup_top_dark);
        int centerDark = a.getResourceId(
                R.styleable.AlertDialog_centerDark, R.drawable.popup_center_dark);
        int bottomDark = a.getResourceId(
                R.styleable.AlertDialog_bottomDark, R.drawable.popup_bottom_dark);
        int fullBright = a.getResourceId(
                R.styleable.AlertDialog_fullBright, R.drawable.popup_full_bright);
        int topBright = a.getResourceId(
                R.styleable.AlertDialog_topBright, R.drawable.popup_top_bright);
        int centerBright = a.getResourceId(
                R.styleable.AlertDialog_centerBright, R.drawable.popup_center_bright);
        int bottomBright = a.getResourceId(
                R.styleable.AlertDialog_bottomBright, R.drawable.popup_bottom_bright);
        int bottomMedium = a.getResourceId(
                R.styleable.AlertDialog_bottomMedium, R.drawable.popup_bottom_medium);
        
        /*
         * We now set the background of all of the sections of the alert.
         * First collect together each section that is being displayed along
         * with whether it is on a light or dark background, then run through
         * them setting their backgrounds.  This is complicated because we need
         * to correctly use the full, top, middle, and bottom graphics depending
         * on how many views they are and where they appear.
         */
        
        View[] views = new View[4];
        boolean[] light = new boolean[4];
        View lastView = null;
        boolean lastLight = false;
        
        int pos = 0;
        if (hasTitle) {
            views[pos] = topPanel;
            light[pos] = false;
            pos++;
        }
        
        /* The contentPanel displays either a custom text message or
         * a ListView. If it's text we should use the dark background
         * for ListView we should use the light background. If neither
         * are there the contentPanel will be hidden so set it as null.
         */
        views[pos] = (contentPanel.getVisibility() == View.GONE) 
                ? null : contentPanel;
        light[pos] = mListView != null;
        pos++;
        if (customPanel != null) {
            views[pos] = customPanel;
            light[pos] = mForceInverseBackground;
            pos++;
        }
        if (hasButtons) {
            views[pos] = buttonPanel;
            light[pos] = true;
        }
        
        boolean setView = false;
        for (pos=0; pos<views.length; pos++) {
            View v = views[pos];
            if (v == null) {
                continue;
            }
            if (lastView != null) {
                if (!setView) {
                    lastView.setBackgroundResource(lastLight ? topBright : topDark);
                } else {
                    lastView.setBackgroundResource(lastLight ? centerBright : centerDark);
                }
                setView = true;
            }
            lastView = v;
            lastLight = light[pos];
        }
        
        if (lastView != null) {
            if (setView) {
                
                /* ListViews will use the Bright background but buttons use
                 * the Medium background.
                 */ 
                lastView.setBackgroundResource(
                        lastLight ? (hasButtons ? bottomMedium : bottomBright) : bottomDark);
            } else {
                lastView.setBackgroundResource(lastLight ? fullBright : fullDark);
            }
        }
        
        /* TODO: uncomment section below. The logic for this should be if 
         * it's a Contextual menu being displayed AND only a Cancel button 
         * is shown then do this.
         */
//        if (hasButtons && (mListView != null)) {
            
            /* Yet another *special* case. If there is a ListView with buttons
             * don't put the buttons on the bottom but instead put them in the
             * footer of the ListView this will allow more items to be
             * displayed.
             */
            
            /*
            contentPanel.setBackgroundResource(bottomBright);
            buttonPanel.setBackgroundResource(centerMedium);
            ViewGroup parent = (ViewGroup) mWindow.findViewById(R.id.parentPanel);
            parent.removeView(buttonPanel);
            AbsListView.LayoutParams params = new AbsListView.LayoutParams(
                    AbsListView.LayoutParams.MATCH_PARENT, 
                    AbsListView.LayoutParams.MATCH_PARENT);
            buttonPanel.setLayoutParams(params);
            mListView.addFooterView(buttonPanel);
            */
//        }
        
        if ((mListView != null) && (mAdapter != null)) {
            mListView.setAdapter(mAdapter);
            if (mCheckedItem > -1) {
                mListView.setItemChecked(mCheckedItem, true);
                mListView.setSelection(mCheckedItem);
            }
        }
    }

首先是获取不同的背景需求，然后去设置对话框不同部分的背景色，首先使用下面代码收集起来各个部分的背景情况（或明或暗）然后根据不同视图的显示设置其顶部、中部、底部的背景。

View[] views = new View[4];
        boolean[] light = new boolean[4];
        View lastView = null;
        boolean lastLight = false;
        
        int pos = 0;
        if (hasTitle) {
            views[pos] = topPanel;
            light[pos] = false;
            pos++;
        }

如果其内容视图显示一个自定义文本或者一个ListView，文本应设置为深色背景，而ListView应设置为浅色背景，如没有内容视图，则设置其背景为null。

views[pos] = (contentPanel.getVisibility() == View.GONE) 
                ? null : contentPanel;
        light[pos] = mListView != null;
        pos++;
        if (customPanel != null) {
            views[pos] = customPanel;
            light[pos] = mForceInverseBackground;
            pos++;
        }
        if (hasButtons) {
            views[pos] = buttonPanel;
            light[pos] = true;
        }
        
        boolean setView = false;
        for (pos=0; pos<views.length; pos++) {
            View v = views[pos];
            if (v == null) {
                continue;
            }
            if (lastView != null) {
                if (!setView) {
                    lastView.setBackgroundResource(lastLight ? topBright : topDark);
                } else {
                    lastView.setBackgroundResource(lastLight ? centerBright : centerDark);
                }
                setView = true;
            }
            lastView = v;
            lastLight = light[pos];
        }
        
        if (lastView != null) {
            if (setView) {
                
                /* ListViews will use the Bright background but buttons use
                 * the Medium background. Listview应明亮些，button应该偏中色背景
                 */ 
                lastView.setBackgroundResource(
                        lastLight ? (hasButtons ? bottomMedium : bottomBright) : bottomDark);
            } else {
                lastView.setBackgroundResource(lastLight ? fullBright : fullDark);
            }
        }

再回到247行，看一些其他设置，设置标题：

public void setTitle(CharSequence title) {
        mTitle = title;
        if (mTitleView != null) {
            mTitleView.setText(title);
        }
    }

设置自定义标题：

 /**
     * @see AlertDialog.Builder#setCustomTitle(View)
     */
    public void setCustomTitle(View customTitleView) {
        mCustomTitleView = customTitleView;
    }

设置显示信息：

   public void setMessage(CharSequence message) {
        mMessage = message;
        if (mMessageView != null) {
            mMessageView.setText(message);
        }
    }

设置Dialog自定义视图：

    /**
     * Set the view to display in the dialog.
     */
    public void setView(View view) {
        mView = view;
        mViewSpacingSpecified = false;
    }

   /**
     * Set the view to display in the dialog along with the spacing around that view
     */
    public void setView(View view, int viewSpacingLeft, int viewSpacingTop, int viewSpacingRight,
            int viewSpacingBottom) {
        mView = view;
        mViewSpacingSpecified = true;
        mViewSpacingLeft = viewSpacingLeft;
        mViewSpacingTop = viewSpacingTop;
        mViewSpacingRight = viewSpacingRight;
        mViewSpacingBottom = viewSpacingBottom;
    }

这个方法可以设置视图到上下左右的间距。

设置按钮和其点击后传送的消息内容：

/**
     * Sets a click listener or a message to be sent when the button is clicked.
     * You only need to pass one of {@code listener} or {@code msg}.
     * 
     * @param whichButton Which button, can be one of
     *            {@link DialogInterface#BUTTON_POSITIVE},
     *            {@link DialogInterface#BUTTON_NEGATIVE}, or
     *            {@link DialogInterface#BUTTON_NEUTRAL}
     * @param text The text to display in positive button.
     * @param listener The {@link DialogInterface.OnClickListener} to use.
     * @param msg The {@link Message} to be sent when clicked.
     */
    public void setButton(int whichButton, CharSequence text,
            DialogInterface.OnClickListener listener, Message msg) {

        if (msg == null && listener != null) {
            msg = mHandler.obtainMessage(whichButton, listener);
        }
        
        switch (whichButton) {

            case DialogInterface.BUTTON_POSITIVE:
                mButtonPositiveText = text;
                mButtonPositiveMessage = msg;
                break;
                
            case DialogInterface.BUTTON_NEGATIVE:
                mButtonNegativeText = text;
                mButtonNegativeMessage = msg;
                break;
                
            case DialogInterface.BUTTON_NEUTRAL:
                mButtonNeutralText = text;
                mButtonNeutralMessage = msg;
                break;
                
            default:
                throw new IllegalArgumentException("Button does not exist");
        }
    }

设置对话框图标：

   /**
     * Set resId to 0 if you don't want an icon.
     * @param resId the resourceId of the drawable to use as the icon or 0
     * if you don't want an icon.
     */
    public void setIcon(int resId) {
        mIconId = resId;
        if (mIconView != null) {
            if (resId > 0) {
                mIconView.setImageResource(mIconId);
            } else if (resId == 0) {
                mIconView.setVisibility(View.GONE);
            }
        }
    }
    
    public void setIcon(Drawable icon) {
        mIcon = icon;
        if ((mIconView != null) && (mIcon != null)) {
            mIconView.setImageDrawable(icon);
        }
    }

	设置对话框后面的窗体是否能够获得焦点（能不能响应用户操作触发的事件）：

public void setInverseBackgroundForced(boolean forceInverseBackground) {
        mForceInverseBackground = forceInverseBackground;
    }

	获取对话框提供的ListView:

public ListView getListView() {
        return mListView;
    }

	获取按钮：

public Button getButton(int whichButton) {
        switch (whichButton) {
            case DialogInterface.BUTTON_POSITIVE:
                return mButtonPositive;
            case DialogInterface.BUTTON_NEGATIVE:
                return mButtonNegative;
            case DialogInterface.BUTTON_NEUTRAL:
                return mButtonNeutral;
            default:
                return null;
        }
    }

	按下或者抬起事件：

@SuppressWarnings({"UnusedDeclaration"})
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        return mScrollView != null && mScrollView.executeKeyEvent(event);
    }

    @SuppressWarnings({"UnusedDeclaration"})
    public boolean onKeyUp(int keyCode, KeyEvent event) {
        return mScrollView != null && mScrollView.executeKeyEvent(event);
    }
	下面定义了一个静态内部类：RecycleListView（此listView Measure状态下回收视图）

public static class RecycleListView extends ListView {
        boolean mRecycleOnMeasure = true;

        public RecycleListView(Context context) {
            super(context);
        }

        public RecycleListView(Context context, AttributeSet attrs) {
            super(context, attrs);
        }

        public RecycleListView(Context context, AttributeSet attrs, int defStyle) {
            super(context, attrs, defStyle);
        }

        @Override
        protected boolean recycleOnMeasure() {
            return mRecycleOnMeasure;
        }
    }

	还剩下最后一个静态内部类：AlertParams

public static class AlertParams {
        public final Context mContext;
        public final LayoutInflater mInflater;
        
        public int mIconId = 0;
        public Drawable mIcon;
        public CharSequence mTitle;
        public View mCustomTitleView;
        public CharSequence mMessage;
        public CharSequence mPositiveButtonText;
        public DialogInterface.OnClickListener mPositiveButtonListener;
        public CharSequence mNegativeButtonText;
        public DialogInterface.OnClickListener mNegativeButtonListener;
        public CharSequence mNeutralButtonText;
        public DialogInterface.OnClickListener mNeutralButtonListener;
        public boolean mCancelable;
        public DialogInterface.OnCancelListener mOnCancelListener;
        public DialogInterface.OnKeyListener mOnKeyListener;
        public CharSequence[] mItems;
        public ListAdapter mAdapter;
        public DialogInterface.OnClickListener mOnClickListener;
        public View mView;
        public int mViewSpacingLeft;
        public int mViewSpacingTop;
        public int mViewSpacingRight;
        public int mViewSpacingBottom;
        public boolean mViewSpacingSpecified = false;
        public boolean[] mCheckedItems;
        public boolean mIsMultiChoice;
        public boolean mIsSingleChoice;
        public int mCheckedItem = -1;
        public DialogInterface.OnMultiChoiceClickListener mOnCheckboxClickListener;
        public Cursor mCursor;
        public String mLabelColumn;
        public String mIsCheckedColumn;
        public boolean mForceInverseBackground;
        public AdapterView.OnItemSelectedListener mOnItemSelectedListener;
        public OnPrepareListViewListener mOnPrepareListViewListener;
        public boolean mRecycleOnMeasure = true;

        /**
         * Interface definition for a callback to be invoked before the ListView
         * will be bound to an adapter.
         */
        public interface OnPrepareListViewListener {
            
            /**
             * Called before the ListView is bound to an adapter.
             * @param listView The ListView that will be shown in the dialog.
             */
            void onPrepareListView(ListView listView);
        }
        
        public AlertParams(Context context) {
            mContext = context;
            mCancelable = true;
            mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        }
    
        public void apply(AlertController dialog) {
            if (mCustomTitleView != null) {
                dialog.setCustomTitle(mCustomTitleView);
            } else {
                if (mTitle != null) {
                    dialog.setTitle(mTitle);
                }
                if (mIcon != null) {
                    dialog.setIcon(mIcon);
                }
                if (mIconId >= 0) {
                    dialog.setIcon(mIconId);
                }
            }
            if (mMessage != null) {
                dialog.setMessage(mMessage);
            }
            if (mPositiveButtonText != null) {
                dialog.setButton(DialogInterface.BUTTON_POSITIVE, mPositiveButtonText,
                        mPositiveButtonListener, null);
            }
            if (mNegativeButtonText != null) {
                dialog.setButton(DialogInterface.BUTTON_NEGATIVE, mNegativeButtonText,
                        mNegativeButtonListener, null);
            }
            if (mNeutralButtonText != null) {
                dialog.setButton(DialogInterface.BUTTON_NEUTRAL, mNeutralButtonText,
                        mNeutralButtonListener, null);
            }
            if (mForceInverseBackground) {
                dialog.setInverseBackgroundForced(true);
            }
            // For a list, the client can either supply an array of items or an
            // adapter or a cursor
            if ((mItems != null) || (mCursor != null) || (mAdapter != null)) {
                createListView(dialog);
            }
            if (mView != null) {
                if (mViewSpacingSpecified) {
                    dialog.setView(mView, mViewSpacingLeft, mViewSpacingTop, mViewSpacingRight,
                            mViewSpacingBottom);
                } else {
                    dialog.setView(mView);
                }
            }
            
            /*
            dialog.setCancelable(mCancelable);
            dialog.setOnCancelListener(mOnCancelListener);
            if (mOnKeyListener != null) {
                dialog.setOnKeyListener(mOnKeyListener);
            }
            */
        }
        
        private void createListView(final AlertController dialog) {
            final RecycleListView listView = (RecycleListView)
                    mInflater.inflate(dialog.mListLayout, null);
            ListAdapter adapter;
            
            if (mIsMultiChoice) {
                if (mCursor == null) {
                    adapter = new ArrayAdapter<CharSequence>(
                            mContext, dialog.mMultiChoiceItemLayout, R.id.text1, mItems) {
                        @Override
                        public View getView(int position, View convertView, ViewGroup parent) {
                            View view = super.getView(position, convertView, parent);
                            if (mCheckedItems != null) {
                                boolean isItemChecked = mCheckedItems[position];
                                if (isItemChecked) {
                                    listView.setItemChecked(position, true);
                                }
                            }
                            return view;
                        }
                    };
                } else {
                    adapter = new CursorAdapter(mContext, mCursor, false) {
                        private final int mLabelIndex;
                        private final int mIsCheckedIndex;

                        {
                            final Cursor cursor = getCursor();
                            mLabelIndex = cursor.getColumnIndexOrThrow(mLabelColumn);
                            mIsCheckedIndex = cursor.getColumnIndexOrThrow(mIsCheckedColumn);
                        }

                        @Override
                        public void bindView(View view, Context context, Cursor cursor) {
                            CheckedTextView text = (CheckedTextView) view.findViewById(R.id.text1);
                            text.setText(cursor.getString(mLabelIndex));
                            listView.setItemChecked(cursor.getPosition(),
                                    cursor.getInt(mIsCheckedIndex) == 1);
                        }
    
                        @Override
                        public View newView(Context context, Cursor cursor, ViewGroup parent) {
                            return mInflater.inflate(dialog.mMultiChoiceItemLayout,
                                    parent, false);
                        }
                        
                    };
                }
            } else {
                int layout = mIsSingleChoice 
                        ? dialog.mSingleChoiceItemLayout : dialog.mListItemLayout;
                if (mCursor == null) {
                    adapter = (mAdapter != null) ? mAdapter
                            : new ArrayAdapter<CharSequence>(mContext, layout, R.id.text1, mItems);
                } else {
                    adapter = new SimpleCursorAdapter(mContext, layout, 
                            mCursor, new String[]{mLabelColumn}, new int[]{R.id.text1});
                }
            }
            
            if (mOnPrepareListViewListener != null) {
                mOnPrepareListViewListener.onPrepareListView(listView);
            }
            
            /* Don't directly set the adapter on the ListView as we might
             * want to add a footer to the ListView later.
             */
            dialog.mAdapter = adapter;
            dialog.mCheckedItem = mCheckedItem;
            
            if (mOnClickListener != null) {
                listView.setOnItemClickListener(new OnItemClickListener() {
                    public void onItemClick(AdapterView parent, View v, int position, long id) {
                        mOnClickListener.onClick(dialog.mDialogInterface, position);
                        if (!mIsSingleChoice) {
                            dialog.mDialogInterface.dismiss();
                        }
                    }
                });
            } else if (mOnCheckboxClickListener != null) {
                listView.setOnItemClickListener(new OnItemClickListener() {
                    public void onItemClick(AdapterView parent, View v, int position, long id) {
                        if (mCheckedItems != null) {
                            mCheckedItems[position] = listView.isItemChecked(position);
                        }
                        mOnCheckboxClickListener.onClick(
                                dialog.mDialogInterface, position, listView.isItemChecked(position));
                    }
                });
            }
            
            // Attach a given OnItemSelectedListener to the ListView
            if (mOnItemSelectedListener != null) {
                listView.setOnItemSelectedListener(mOnItemSelectedListener);
            }
            
            if (mIsSingleChoice) {
                listView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
            } else if (mIsMultiChoice) {
                listView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
            }
            listView.mRecycleOnMeasure = mRecycleOnMeasure;
            dialog.mListView = listView;
        }
    }

绝大多数参数都比较简单，从字面意思就可以看明白，挑选几个参数简单说明一下：

mWindow：窗体类

mListView：可以对外提供一个ListView

mViewSpacingLeft：设置视图左边间隔

mViewSpacingSpecified：视图是否是指定间距（默认为false）

mCheckedItems：bool值，多选框是否被选中

mIsMultiChoice：是否是多选

可以简单的认为AlertParams类为AlertController的工具类，看下其里面的两个方法，第一个apply：

public void apply(AlertController dialog) {
            if (mCustomTitleView != null) {
                dialog.setCustomTitle(mCustomTitleView);
            } else {
                if (mTitle != null) {
                    dialog.setTitle(mTitle);
                }
                if (mIcon != null) {
                    dialog.setIcon(mIcon);
                }
                if (mIconId >= 0) {
                    dialog.setIcon(mIconId);
                }
            }
            if (mMessage != null) {
                dialog.setMessage(mMessage);
            }
            if (mPositiveButtonText != null) {
                dialog.setButton(DialogInterface.BUTTON_POSITIVE, mPositiveButtonText,
                        mPositiveButtonListener, null);
            }
            if (mNegativeButtonText != null) {
                dialog.setButton(DialogInterface.BUTTON_NEGATIVE, mNegativeButtonText,
                        mNegativeButtonListener, null);
            }
            if (mNeutralButtonText != null) {
                dialog.setButton(DialogInterface.BUTTON_NEUTRAL, mNeutralButtonText,
                        mNeutralButtonListener, null);
            }
            if (mForceInverseBackground) {
                dialog.setInverseBackgroundForced(true);
            }
            // For a list, the client can either supply an array of items or an
            // adapter or a cursor
            if ((mItems != null) || (mCursor != null) || (mAdapter != null)) {
                createListView(dialog);
            }
            if (mView != null) {
                if (mViewSpacingSpecified) {
                    dialog.setView(mView, mViewSpacingLeft, mViewSpacingTop, mViewSpacingRight,
                            mViewSpacingBottom);
                } else {
                    dialog.setView(mView);
                }
            }
            
            /*
            dialog.setCancelable(mCancelable);
            dialog.setOnCancelListener(mOnCancelListener);
            if (mOnKeyListener != null) {
                dialog.setOnKeyListener(mOnKeyListener);
            }
            */
        }

为Dialog设置各种属性，在AlertDialog.Builder的create（）方法中调用了该方法。

为Dialog创建一个listView：

private void createListView(final AlertController dialog) {
            final RecycleListView listView = (RecycleListView)
                    mInflater.inflate(dialog.mListLayout, null);
            ListAdapter adapter;
            //是否是多选
            if (mIsMultiChoice) {
		  //是否是从数据库中取出的值
                if (mCursor == null) {
                    adapter = new ArrayAdapter<CharSequence>(
                            mContext, dialog.mMultiChoiceItemLayout, R.id.text1, mItems) {
                        @Override
                        public View getView(int position, View convertView, ViewGroup parent) {
                            View view = super.getView(position, convertView, parent);
                            if (mCheckedItems != null) {
                                boolean isItemChecked = mCheckedItems[position];
                                if (isItemChecked) {
                                    listView.setItemChecked(position, true);
                                }
                            }
                            return view;
                        }
                    };
                } else {
                    adapter = new CursorAdapter(mContext, mCursor, false) {
                        private final int mLabelIndex;
                        private final int mIsCheckedIndex;

                        {
                            final Cursor cursor = getCursor();
                            mLabelIndex = cursor.getColumnIndexOrThrow(mLabelColumn);
                            mIsCheckedIndex = cursor.getColumnIndexOrThrow(mIsCheckedColumn);
                        }

                        @Override
                        public void bindView(View view, Context context, Cursor cursor) {
                            CheckedTextView text = (CheckedTextView) view.findViewById(R.id.text1);
                            text.setText(cursor.getString(mLabelIndex));
                            listView.setItemChecked(cursor.getPosition(),
                                    cursor.getInt(mIsCheckedIndex) == 1);
                        }
    
                        @Override
                        public View newView(Context context, Cursor cursor, ViewGroup parent) {
                            return mInflater.inflate(dialog.mMultiChoiceItemLayout,
                                    parent, false);
                        }
                        
                    };
                }
            } else {
		//如果是单选或者普通的listview
                int layout = mIsSingleChoice 
                        ? dialog.mSingleChoiceItemLayout : dialog.mListItemLayout;
                if (mCursor == null) {
                    adapter = (mAdapter != null) ? mAdapter
                            : new ArrayAdapter<CharSequence>(mContext, layout, R.id.text1, mItems);
                } else {
                    adapter = new SimpleCursorAdapter(mContext, layout, 
                            mCursor, new String[]{mLabelColumn}, new int[]{R.id.text1});
                }
            }
            
            if (mOnPrepareListViewListener != null) {
                mOnPrepareListViewListener.onPrepareListView(listView);
            }
            
            /* Don't directly set the adapter on the ListView as we might
             * want to add a footer to the ListView later.
	      * 不要直接为listView设置adapter，因为一会可能需要为listView设置页脚
             */
            dialog.mAdapter = adapter;
            dialog.mCheckedItem = mCheckedItem;
            
	     //设置监听
            if (mOnClickListener != null) {
                listView.setOnItemClickListener(new OnItemClickListener() {
                    public void onItemClick(AdapterView parent, View v, int position, long id) {
                        mOnClickListener.onClick(dialog.mDialogInterface, position);
                        if (!mIsSingleChoice) {
                            dialog.mDialogInterface.dismiss();
                        }
                    }
                });
            } else if (mOnCheckboxClickListener != null) { //多选监听
                listView.setOnItemClickListener(new OnItemClickListener() {
                    public void onItemClick(AdapterView parent, View v, int position, long id) {
                        if (mCheckedItems != null) {
                            mCheckedItems[position] = listView.isItemChecked(position);
                        }
                        mOnCheckboxClickListener.onClick(
                                dialog.mDialogInterface, position, listView.isItemChecked(position));
                    }
                });
            }
            
            // Attach a given OnItemSelectedListener to the ListView
            if (mOnItemSelectedListener != null) {
                listView.setOnItemSelectedListener(mOnItemSelectedListener);
            }
            
	     //如有选择项，选择单选或者多选
            if (mIsSingleChoice) {
                listView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
            } else if (mIsMultiChoice) {
                listView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
            }
            listView.mRecycleOnMeasure = mRecycleOnMeasure;
            dialog.mListView = listView;
        }
    }

这个方法逻辑注释在代码中，不详细解释了，都比较简单。

看AlertController源码，可以结合AlertDialog源码看。因为在AlertDialog中的大部分功能实现是靠调用AlertController类来实现。

更多源码解析：Android源码解析

PS：终于简单的把这篇源码看完，距离AlertDialog已经有一个月了，时间飞快，多需努力，我想回家。