Android 模仿QQ登录界面解决软键盘遮挡问题

Android 软件盘弹出可能会遮挡住界面上的某些控件。当 windowSoftInputMode 为 adjustPan 时，一般不会挡住 EditText，但是假如 EditText 下面是一个登录按钮，那么这个按钮就可能被挡住，但有时我们希望用户输完密码可以直接点击登录按钮，而不用把软键盘收起来。这时就需要用到 adjustResize，这种模式能够获取到软键盘的高度，这样我们就能够精确的对界面进行控制。

在阅读本章之前，你应该了解 windowSoftInputMode 的一些属性，特别是 adjustResize，如果还不熟悉，建议先阅读Android 软键盘之 windowSoftInputMode 分析再回过头来继续往下看。

QQ 登录界面很好的解决了软键盘遮挡问题，当然在大屏手机上软键盘并不会挡住登录按钮。今天我们也来模仿一个 QQ 登录界面，最终效果如下：

QQ登录界面

监听软键盘弹出及收起事件

step1. 指定 windowSoftInputMode="adjustResize"

在 AndroidManifest.xml 中相应的 Activity 设置 android:windowSoftInputMode="adjustResize"，也可以在 java 代码中设置。

step2. 监听 contentView 宽高(layout) 变化

获取 ViewTreeObserver 并监听 OnGlobalLayoutListener, 当viewTree的布局发生变化时onGlobalLayout将会回调。我们新建一个KeyboardHelper辅助类。

KeyboardHelper.java

public class KeyboardHelper {
    private Activity activity;
    private OnKeyboardStatusChangeListener onKeyboardStatusChangeListener;
    private int windowBottom = -1;
    private int keyboardHeight = 0;

    public KeyboardHelper(Activity activity) {
        this.activity = activity;
        activity.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE);
        if (activity.getRequestedOrientation() != ActivityInfo.SCREEN_ORIENTATION_PORTRAIT) {
            activity.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
        }
    }

    public void onCreate() {
        View content = activity.findViewById(android.R.id.content);
        // content.addOnLayoutChangeListener(listener); 这个方法有时会出现一些问题
        content.getViewTreeObserver().addOnGlobalLayoutListener(onGlobalLayoutListener);
    }

    public void onDestroy() {
        View content = activity.findViewById(android.R.id.content);
        ViewUtils.removeOnGlobalLayoutListener(content, onGlobalLayoutListener);
    }

    private OnGlobalLayoutListener onGlobalLayoutListener = new OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            Rect rect = new Rect();
            activity.getWindow().getDecorView().getWindowVisibleDisplayFrame(rect);
            Log.d("KeyboardHelper", "onGlobalLayout: " + rect + ", " + windowBottom);
            int newBottom = rect.bottom;
            if (windowBottom != -1 && windowBottom != newBottom) {
                if (newBottom < windowBottom) {
                    // keyboard pop
                    keyboardHeight = windowBottom - newBottom;
                    if (onKeyboardStatusChangeListener != null) {
                        onKeyboardStatusChangeListener.onKeyboardPop(keyboardHeight);
                    }
                } else {
                    // keyboard close
                    if (onKeyboardStatusChangeListener != null) {
                        onKeyboardStatusChangeListener.onKeyboardClose(keyboardHeight);
                    }
                }
            }
            windowBottom = newBottom;
        }
    };

    public void setOnKeyboardStatusChangeListener(
            OnKeyboardStatusChangeListener onKeyboardStatusChangeListener) {
        this.onKeyboardStatusChangeListener = onKeyboardStatusChangeListener;
    }
    
    public interface OnKeyboardStatusChangeListener {

        void onKeyboardPop(int keyboardHeight);

        void onKeyboardClose(int keyboardHeight);
    }
}

ViewUtils.java

public class ViewUtils {

    public static void removeOnGlobalLayoutListener(View view, ViewTreeObserver.OnGlobalLayoutListener onGlobalLayoutListener) {
        if (Build.VERSION.SDK_INT < 16) {
            view.getViewTreeObserver().removeGlobalOnLayoutListener(onGlobalLayoutListener);
        } else {
            view.getViewTreeObserver().removeOnGlobalLayoutListener(onGlobalLayoutListener);
        }
    }

}

代码比较简单，无非是获取window的可视坐标，通过比较bottom的值来判断软键盘是弹出还是收起。

实现 QQ 登录界面

有了这个 KeyBoardHelper，那么要实现和 QQ 登录界面一样的效果就不难了。我们甚至不需要任何自定义控件。思路是在软键盘弹出时，把登录按钮以上的布局往上移，只要为其设置一个负值的 topMargin 即可。

如图所示：

QQ登录界面示意图

MainActivity 代码如下：

public class MainActivity extends Activity {

    private int bottomHeight;
    private KeyboardHelper keyboardHelper;
    private View layoutBottom;
    private View layoutContent;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_qq_login);

        layoutContent = findViewById(R.id.layout_content);
        layoutBottom = findViewById(R.id.layout_bottom);
        keyboardHelper = new KeyboardHelper(this);
        keyboardHelper.onCreate();
        keyboardHelper.setOnKeyboardStatusChangeListener(onKeyBoardStatusChangeListener);
        layoutBottom.post(new Runnable() {
            @Override
            public void run() {
                bottomHeight = layoutBottom.getHeight();
            }
        });
    }

    private OnKeyboardStatusChangeListener onKeyBoardStatusChangeListener = new OnKeyboardStatusChangeListener() {

        @Override
        public void onKeyboardPop(int keyboardHeight) {

            final int height = keyboardHeight;
            if (bottomHeight > height) {
                layoutBottom.setVisibility(View.GONE);
            } else {
                int offset = bottomHeight - height;
                final ViewGroup.MarginLayoutParams lp = (MarginLayoutParams) layoutContent
                        .getLayoutParams();
                lp.topMargin = offset;
                layoutContent.setLayoutParams(lp);
            }

        }

        @Override
        public void onKeyboardClose(int keyboardHeight) {
            if (View.VISIBLE != layoutBottom.getVisibility()) {
                layoutBottom.postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        layoutBottom.setVisibility(View.VISIBLE);
                    }
                }, 300);
            }
            final ViewGroup.MarginLayoutParams lp = (MarginLayoutParams) layoutContent
                    .getLayoutParams();
            if (lp.topMargin != 0) {
                lp.topMargin = 0;
                layoutContent.setLayoutParams(lp);
            }

        }
    };

    @Override
    protected void onDestroy() {
        super.onDestroy();
        keyboardHelper.onDestroy();
    }
}

布局文件：activity_qq_login.xml

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