Android开发教程之获取系统输入法高度的正确姿势
问题与解决
在Android应用的开发中，有一些需求需要我们获取到输入法的高度，但是官方的API并没有提供类似的方法，所以我们需要自己来实现。
查阅了网上很多资料，试过以后都不理想。
比如有的方法通过监听布局的变化来计算输入法的高度，这种方式在Activity的配置中配置为"android:windowSoftInputMode="adjustResize""时没有问题，可以正确获取输入法的高度，因为布局此时确实会动态的调整。
但是当Activity配置为"android:windowSoftInputMode="adjustNothing""时，布局不会在输入法弹出时进行调整，上面的方式就会扑街。
不过经过一番探索和测试，终于发现了一种方式可以在即使设置为adjustNothing时也可以正确计算高度放方法。
同时也感谢这位外国朋友：
GitHub地址
方法如下
其实也就两个类，我也做了一些修改，解决了一些问题，这里也贴出来：
KeyboardHeightObserver.java
/**
*Theobserverthatwillbenotifiedwhentheheightof
*thekeyboardhaschanged
*/
publicinterfaceKeyboardHeightObserver{
/**
*Calledwhenthekeyboardheighthaschanged,0meanskeyboardisclosed,
*>=1meanskeyboardisopened.
*
*@paramheightTheheightofthekeyboardinpixels
*@paramorientationTheorientationeither:Configuration.ORIENTATION_PORTRAITor
*Configuration.ORIENTATION_LANDSCAPE
*/
voidonKeyboardHeightChanged(intheight,intorientation);
}
KeyboardHeightProvider.java
/**
*Thekeyboardheightprovider,thisclassusesaPopupWindow
*tocalculatethewindowheightwhenthefloatingkeyboardisopenedandclosed.
*/
publicclassKeyboardHeightProviderextendsPopupWindow{
/**Thetagforloggingpurposes*/
privatefinalstaticStringTAG="sample_KeyboardHeightProvider";
/**Thekeyboardheightobserver*/
privateKeyboardHeightObserverobserver;
/**Thecachedlandscapeheightofthekeyboard*/
privateintkeyboardLandscapeHeight;
/**Thecachedportraitheightofthekeyboard*/
privateintkeyboardPortraitHeight;
/**Theviewthatisusedtocalculatethekeyboardheight*/
privateViewpopupView;
/**Theparentview*/
privateViewparentView;
/**TherootactivitythatusesthisKeyboardHeightProvider*/
privateActivityactivity;
/**
*ConstructanewKeyboardHeightProvider
*
*@paramactivityTheparentactivity
*/
publicKeyboardHeightProvider(Activityactivity){
super(activity);
this.activity=activity;
LayoutInflaterinflator=(LayoutInflater)activity.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
this.popupView=inflator.inflate(R.layout.keyboard_popup_window,null,false);
setContentView(popupView);
setSoftInputMode(LayoutParams.SOFT_INPUT_ADJUST_RESIZE|LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);
setInputMethodMode(PopupWindow.INPUT_METHOD_NEEDED);
parentView=activity.findViewById(android.R.id.content);
setWidth(0);
setHeight(LayoutParams.MATCH_PARENT);
popupView.getViewTreeObserver().addOnGlobalLayoutListener(newOnGlobalLayoutListener(){
@Override
publicvoidonGlobalLayout(){
if(popupView!=null){
handleOnGlobalLayout();
}
}
});
}
/**
*StarttheKeyboardHeightProvider,thismustbecalledaftertheonResumeoftheActivity.
*PopupWindowsarenotallowedtoberegisteredbeforetheonResumehasfinished
*oftheActivity.
*/
publicvoidstart(){
if(!isShowing()&&parentView.getWindowToken()!=null){
setBackgroundDrawable(newColorDrawable(0));
showAtLocation(parentView,Gravity.NO_GRAVITY,0,0);
}
}
/**
*Closethekeyboardheightprovider,
*thisproviderwillnotbeusedanymore.
*/
publicvoidclose(){
this.observer=null;
dismiss();
}
/**
*Setthekeyboardheightobservertothisprovider.The
*observerwillbenotifiedwhenthekeyboardheighthaschanged.
*Forexamplewhenthekeyboardisopenedorclosed.
*
*@paramobserverTheobservertobeaddedtothisprovider.
*/
publicvoidsetKeyboardHeightObserver(KeyboardHeightObserverobserver){
this.observer=observer;
}
/**
*Getthescreenorientation
*
*@returnthescreenorientation
*/
privateintgetScreenOrientation(){
returnactivity.getResources().getConfiguration().orientation;
}
/**
*PopupwindowitselfisasbigasthewindowoftheActivity.
*Thekeyboardcanthenbecalculatedbyextractingthepopupviewbottom
*fromtheactivitywindowheight.
*/
privatevoidhandleOnGlobalLayout(){
PointscreenSize=newPoint();
activity.getWindowManager().getDefaultDisplay().getSize(screenSize);
Rectrect=newRect();
popupView.getWindowVisibleDisplayFrame(rect);
//REMIND,youmayliketochangethisusingthefullscreensizeofthephone
//andalsousingthestatusbarandnavigationbarheightsofthephonetocalculate
//thekeyboardheight.ButthisworkedfineonaNexus.
intorientation=getScreenOrientation();
intkeyboardHeight=screenSize.y-rect.bottom;
if(keyboardHeight==0){
notifyKeyboardHeightChanged(0,orientation);
}
elseif(orientation==Configuration.ORIENTATION_PORTRAIT){
this.keyboardPortraitHeight=keyboardHeight;
notifyKeyboardHeightChanged(keyboardPortraitHeight,orientation);
}
else{
this.keyboardLandscapeHeight=keyboardHeight;
notifyKeyboardHeightChanged(keyboardLandscapeHeight,orientation);
}
}
privatevoidnotifyKeyboardHeightChanged(intheight,intorientation){
if(observer!=null){
observer.onKeyboardHeightChanged(height,orientation);
}
}
}
使用方法
此处以在Activity中的使用进行举例。
实现接口
引入这两个类后，在当前Activity中实现接口KeyboardHeightObserver：
@Override
publicvoidonKeyboardHeightChanged(intheight,intorientation){
Stringor=orientation==Configuration.ORIENTATION_PORTRAIT?"portrait":"landscape";
Logger.d(TAG,"onKeyboardHeightChangedinpixels:"+height+""+or);
}
定义并初始化
在当前Activity定义成员变量，并在onCreate()中进行初始化
privateKeyboardHeightProvidermKeyboardHeightProvider;
@Override
protectedvoidonCreate(@NullableBundlesavedInstanceState){
...
mKeyboardHeightProvider=newKeyboardHeightProvider(this);
newHandler().post(()->mKeyboardHeightProvider.start());
}
生命周期处理
初始化完成后，我们要在Activity中的生命周期中也要进行处理，以免内存泄露。
@Override
protectedvoidonResume(){
super.onResume();
mKeyboardHeightProvider.setKeyboardHeightObserver(this);
}
@Override
protectedvoidonPause(){
super.onPause();
mKeyboardHeightProvider.setKeyboardHeightObserver(null);
}
@Override
protectedvoidonDestroy(){
super.onDestroy();
mKeyboardHeightProvider.close();
}
总结
此时我们就可以正确获取的当前输入法的高度了，即使android:windowSoftInputMode="adjustNothing"时也可以正确获取到，这正是这个方法的强大之处，利用这个方法可以实现比如类似微信聊天的界面，流畅切换输入框，表情框等。
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