Android沉浸式布局导致的键盘遮挡问题处理方案

前言

公司项目——沉浸式布局
沉浸式方案：全屏+透明状态栏
问题：键盘遮挡输入框
解决思路：检测键盘是否弹起，根据键盘的弹起与回收，重新绘制界面
解决方案：AndroidBug5497Workaround

代码

public class AndroidBug5497Workaround {
    //该解决方案用于处理 全屏下键盘 问题 :
    //当Theme为 @android:style/Theme.Light.NoTitleBar.Fullscreen 时
    //android:windowSoftInputMode="adjustResize" 无效
    // 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.
    
    //紧随setContentView之后调用
    public static void assistActivity (Activity activity) {
        new AndroidBug5497Workaround(activity);
    }
    
    private View mChildOfContent;
    private int usableHeightPrevious;
    private FrameLayout.LayoutParams frameLayoutParams;
	
    private AndroidBug5497Workaround(Activity activity) {
        //获取Activity的最外层布局
        FrameLayout content = (FrameLayout) activity.findViewById(android.R.id.content);
        mChildOfContent = content.getChildAt(0);
        
        //监听键盘弹起与收回
        mChildOfContent.getViewTreeObserver().addOnGlobalLayoutListener(
            new ViewTreeObserver.OnGlobalLayoutListener() {
                public void onGlobalLayout() {
                    possiblyResizeChildOfContent();
                }
            }
        );
        //重置页面属性
        frameLayoutParams = (FrameLayout.LayoutParams) mChildOfContent.getLayoutParams();
    }
	
    // 获取界面可用高度，如果软键盘弹起后，Activity的xml布局可用高度需要减去键盘高度 
    private void possiblyResizeChildOfContent() {
        int usableHeightNow = computeUsableHeight();
		
        //判断 当前可用高度和 历史可用高度不同 （即键盘状态发生变化） 时，调整界面高度
        if (usableHeightNow != usableHeightPrevious) {
            int usableHeightSansKeyboard = mChildOfContent.getRootView().getHeight();
            int heightDifference = usableHeightSansKeyboard - usableHeightNow;
            //将 可用高度的1/4视为键盘高度
            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;
        }
    }
	
    //获取页面可用高度
    private int computeUsableHeight() {
        Rect r = new Rect();
        mChildOfContent.getWindowVisibleDisplayFrame(r);
        //全屏应用 不需要减去 top , r.top 为状态栏高度，r.bottom 为屏幕可用最底部高度
        //return r.bottom;
        return (r.bottom - r.top);
    }
}

参考文档

google-issues-5497（code.google.com）
Android-5497问题解决方案（github.com）
据说能解决5497方案的兼容问题（jianshu.com）