近期一个任务是修改在 system/framework 出现更新的时候，系统重启展示的升级对话框。

第一步，定位文件位置。过程不必赘述，细究起来可以去研究Android系统的启动流程。

目标位置:frameworks/base/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java

的4731行的showBootMessage()方法。

public void showBootMessage(final CharSequence msg, final boolean always) {

if (mHeadless) return;

mHandler.post(new Runnable() {

@Override public void run() {

if (mBootMsgDialog == null) {

mBootMsgDialog = new ProgressDialog(mContext) {

// This dialog will consume all events coming in to

// it, to avoid it trying to do things too early in boot.

@Override public boolean dispatchKeyEvent(KeyEvent event) {

return true;

}

@Override public boolean dispatchKeyShortcutEvent(KeyEvent event) {

return true;

}

@Override public boolean dispatchTouchEvent(MotionEvent ev) {

return true;

}

@Override public boolean dispatchTrackballEvent(MotionEvent ev) {

return true;

}

@Override public boolean dispatchGenericMotionEvent(MotionEvent ev) {

return true;

}

@Override public boolean dispatchPopulateAccessibilityEvent(

AccessibilityEvent event) {

return true;

}

};

mBootMsgDialog.setTitle(R.string.android_upgrading_title);

mBootMsgDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);

mBootMsgDialog.setIndeterminate(true);

mBootMsgDialog.getWindow().setType(

WindowManager.LayoutParams.TYPE_BOOT_PROGRESS);

mBootMsgDialog.getWindow().addFlags(

WindowManager.LayoutParams.FLAG_DIM_BEHIND

| WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN);

mBootMsgDialog.getWindow().setDimAmount(1);

WindowManager.LayoutParams lp = mBootMsgDialog.getWindow().getAttributes();

lp.screenOrientation = ActivityInfo.SCREEN_ORIENTATION_NOSENSOR;

mBootMsgDialog.getWindow().setAttributes(lp);

mBootMsgDialog.setCancelable(false);

mBootMsgDialog.show();

WindowManager.LayoutParams wlp = mBootMsgDialog.getWindow().getAttributes(); wlp.width=dip2px(460,mContext);

wlp.height=dip2px(322,mContext);

wlp.gravity= Gravity.CENTER;

mBootMsgDialog.getWindow().setAttributes(wlp); mBootMsgDialog.getWindow().findViewById(R.id.customPanel).setBackgroundColor(mContext.getResources().getColor(R.color.jidou_dialog_transparent));

}

mBootMsgDialog.setMessage(msg);

}

});

}

这里需要注意的是，配置dialog的长宽，和隐藏dialog的背景黑色。最简单的方法请看代码show()和它下面几行的设置。基本上是可以解决问题。注意要先show().

找到了，接下来就是操刀修改了。这个对话框比较简单，截图也比较麻烦，就不上图了。