解决android 软键盘在全屏下设置adjustResize无效的问题

全屏模式下，即使将activity的windowSoftInputMode的属性设置为：adjustResize，在键盘显示时它未将Activity的Screen向上推动，所以你Activity的view的根树的尺寸是没有变化的。在这种情况下，你也就无法得知键盘的尺寸，对根view的作相应的推移。全屏下的键盘无法Resize的问题从2.1就已经存在了，直到现在google还未给予解决。
感谢Ricardo提供的轮子，他在stackoverflow找到了解决方案。有人已经封装好了该类，你只需引用就OK了。

使用方法

在你的Activity的oncreate()方法里调用AndroidBug5497Workaround.assistActivity(this);即可。注意：在setContentView(R.layout.xxx)之后调用。

//Workaround to get adjustResize functionality for input methos when the fullscreen mode is on
//found by Ricardo
//taken from http://stackoverflow.com/a/19494006 
import android.app.Activity;
import android.graphics.Rect;
import android.view.View;
import android.view.ViewTreeObserver;
import android.widget.FrameLayout;

public class AndroidBug5497Workaround {

// For more information, see https://code.google.com/p/android/issues/detail?id=5497 // To use this class, simply invoke assistActivity() on an Activity that already has its content view set.

public static void assistActivity (Activity activity) {
new AndroidBug5497Workaround(activity);
}

private View mChildOfContent;
private int usableHeightPrevious;
private FrameLayout.LayoutParams frameLayoutParams;

private AndroidBug5497Workaround(Activity activity) {
FrameLayout content = (FrameLayout) activity.findViewById(android.R.id.content);
mChildOfContent = content.getChildAt(0);
mChildOfContent.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
public void onGlobalLayout() {
possiblyResizeChildOfContent();
}
});
frameLayoutParams = (FrameLayout.LayoutParams) mChildOfContent.getLayoutParams();
}

private void possiblyResizeChildOfContent() {
int usableHeightNow = computeUsableHeight();
if (usableHeightNow != usableHeightPrevious) {
int usableHeightSansKeyboard = mChildOfContent.getRootView().getHeight();
int heightDifference = usableHeightSansKeyboard - usableHeightNow;
if (heightDifference > (usableHeightSansKeyboard/4)) {
// keyboard probably just became visible
frameLayoutParams.height = usableHeightSansKeyboard - heightDifference;
} else {
// keyboard probably just became hidden
frameLayoutParams.height = usableHeightSansKeyboard;
}
mChildOfContent.requestLayout();
usableHeightPrevious = usableHeightNow;
}
}

private int computeUsableHeight() {
Rect r = new Rect();
mChildOfContent.getWindowVisibleDisplayFrame(r);
if(r.top==0){
r.top=statusBarH;//状态栏目的高度
}
return (r.bottom - r.top);
}

}