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：
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() {@Overridepublic 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 popkeyboardHeight = windowBottom - newBottom;if (onKeyboardStatusChangeListener != null) {onKeyboardStatusChangeListener.onKeyboardPop(keyboardHeight);}} else {// keyboard closeif (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：
MainActivity 代码如下：
public class MainActivity extends Activity {private int bottomHeight;private KeyboardHelper keyboardHelper;private View layoutBottom;private View layoutContent;@Overrideprotected 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() {@Overridepublic void run() {bottomHeight = layoutBottom.getHeight();}});}private OnKeyboardStatusChangeListener onKeyBoardStatusChangeListener = new OnKeyboardStatusChangeListener() {@Overridepublic 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);}}@Overridepublic void onKeyboardClose(int keyboardHeight) {if (View.VISIBLE != layoutBottom.getVisibility()) {layoutBottom.postDelayed(new Runnable() {@Overridepublic void run() {layoutBottom.setVisibility(View.VISIBLE);}}, 300);}final ViewGroup.MarginLayoutParams lp = (MarginLayoutParams) layoutContent.getLayoutParams();if (lp.topMargin != 0) {lp.topMargin = 0;layoutContent.setLayoutParams(lp);}}};@Overrideprotected void onDestroy() {super.onDestroy();keyboardHelper.onDestroy();}}
布局文件：activity_qq_login.xml
<FrameLayout xmlns:android="/apk/res/android"xmlns:tools="/tools"android:id="@+id/layout_root"android:layout_width="match_parent"android:layout_height="match_parent"><LinearLayout android:id="@+id/layout_content"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical"android:paddingTop="50dp"><ImageView android:id="@+id/imageView"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_gravity="center_horizontal"android:layout_marginTop="18dp"android:contentDescription="marginTop68dp"android:scaleType="centerInside"android:src="@drawable/qq_ava"android:visibility="visible" /><TextView android:layout_width="match_parent"android:layout_height="wrap_content"android:layout_marginTop="18dp"android:background="#f3f0f0"android:paddingBottom="100dp"android:paddingLeft="10dp"android:paddingRight="10dp"android:paddingTop="100dp"android:text="这里为了演示增加一个TextView使登陆按钮在键盘底部"android:textColor="#333333"android:textSize="13sp" /><LinearLayout android:id="@+id/layout_ed"android:layout_width="match_parent"android:layout_height="wrap_content"android:background="#ffffff"android:divider="@drawable/divider"android:orientation="vertical"android:showDividers="middle"><EditTextandroid:layout_width="match_parent"android:layout_height="wrap_content"android:background="@null"android:hint="QQ号/手机号/邮箱"android:padding="10dp"android:textColor="#000000"android:textColorHint="#d2d2d2"android:textCursorDrawable="@null" /><EditTextandroid:layout_width="match_parent"android:layout_height="wrap_content"android:background="@null"android:hint="密码"android:padding="10dp"android:textColor="#000000"android:textColorHint="#d2d2d2"android:textCursorDrawable="@null" /></LinearLayout><Button android:layout_width="match_parent"android:layout_height="wrap_content"android:layout_marginLeft="14dp"android:layout_marginRight="14dp"android:layout_marginTop="14dp"android:background="@drawable/btn_login"android:text="登陆"android:textSize="17sp" /><RelativeLayout android:id="@+id/layout_bottom"android:layout_width="match_parent"android:layout_height="match_parent"><TextViewandroid:id="@+id/tv_cannot_login"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_alignParentBottom="true"android:layout_margin="14dp"android:text="无法登陆？"android:textColor="@color/action_bar_bg"android:textSize="14sp" /><TextViewandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_alignParentBottom="true"android:layout_alignParentRight="true"android:layout_margin="14dp"android:text="新用户"android:textColor="@color/action_bar_bg"android:textSize="14sp" /></RelativeLayout></LinearLayout><include android:id="@+id/appbar"layout="@layout/appbar"android:layout_width="match_parent"android:layout_height="50dp" /></FrameLayout>
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