一般 *android:windowSoftInputMode="adjustResize" *就能解决软键盘遮住输入框的问题，但是当Activity设为Full Screen这个设置就无效了。
下面这个类就能解决这个问题：

public class AndroidBugWorkaround {
    // 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 AndroidBugWorkaround(activity);
    }
    
    private View mChildOfContent;
    private int usableHeightPrevious;
    private FrameLayout.LayoutParams frameLayoutParams;
    
    private AndroidBugWorkaround(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);
        return r.bottom;
    }
}

只需要在Activity中的 onCreate() 方法中 setContentView() 后面添加
AndroidBugWorkaround.assistActivity(this);即可。

备注：computeUsableHeight() 方法返回值根据fitSystemWindows的设置值来决定，如果布局中fitsSystemWindows="false", return r.bottom; 如果fitsSystemWindows="true", return (r.bottom - r.top);

参考链接