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
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/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">
<EditText
android: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" />
<EditText
android: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">
<TextView
android: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" />
<TextView
android: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>
