完美解決android軟鍵盤監聽

時間 2019-11-07

原文原文鏈接

最近在作應用性能調優，發如今一個包含有輸入框的Activity中，當軟鍵盤彈出的時候，若是直接finish掉此Activity，那麼在返回到上一個Activity時，界面的渲染會因爲軟鍵盤沒有及時的收起而出現卡頓的狀況。
很不友好。
因而，本着geek的精神，作就作到極致，就嘗試着對這一塊作優化。
藉助網上一些知識的分享，同時結合本身的理解，最終應用到項目中。
直接上代碼。。
首先，在manifest文件中聲明此Activity的windowSoftInputMode屬性，android

1 android:windowSoftInputMode="stateVisible|adjustResize" ide

在Activity中聲明所需用到的變量以及佈局的事件監聽，工具

 1 private boolean mBackEnable = false;
 2     private boolean mIsBtnBack = false;
 3     private int rootBottom = Integer.MIN_VALUE;
 4     private OnGlobalLayoutListener mOnGlobalLayoutListener = new OnGlobalLayoutListener() {
 5         @Override
 6         public void onGlobalLayout() {
 7             Rect r = new Rect();
 8             mSearchLayout.getGlobalVisibleRect(r);
 9             // 進入Activity時會佈局，第一次調用onGlobalLayout，先記錄開始軟鍵盤沒有彈出時底部的位置
10             if (rootBottom == Integer.MIN_VALUE) {
11                 rootBottom = r.bottom;
12                 return;
13             }
14             // adjustResize，軟鍵盤彈出後高度會變小
15             if (r.bottom < rootBottom) {
16                 mBackEnable = false;
17             } else {
18                 mBackEnable = true;
19                 if (mIsBtnBack) {
20                     finish();
21                 }
22             }
23         }
24     };

而後在onCreat方法中去註冊事件監聽佈局

1 mSearchLayout.getViewTreeObserver().addOnGlobalLayoutListener(mOnGlobalLayoutListener); 性能

注意：這個mSearchlayout是你整個Activity的佈局引用優化

最後，別忘了，在onDestroy方法中回收掉事件的監聽ui

 1 @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
 2     @Override
 3     protected void onDestroy() {
 4         if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.JELLY_BEAN) {
 5             mSearchLayout.getViewTreeObserver().removeGlobalOnLayoutListener(mOnGlobalLayoutListener);
 6         } else {
 7             mSearchLayout.getViewTreeObserver().removeOnGlobalLayoutListener(mOnGlobalLayoutListener);
 8         }
 9         super.onDestroy();
10     }

到這裏，android軟鍵盤的監聽就結束了。this

**什麼？你說全屏的時候，沒有效果？？？**spa

好吧，我也遇到了。。。code

我在項目中實現了全部界面的沉浸式效果，本覺得Activity設置了adjustResize，OnGlobalLayoutListener仍然能監聽軟鍵盤的變化，結果倒是屢試不行。。。

無奈，只能求助。查了一些資料，發現這原來是android的一個bug。下面是具體的bug修復代碼片斷

 1 public class AndroidAdjustResizeBugFix {
 2     private View mChildOfContent;
 3     private int usableHeightPrevious;
 4     private int statusBarHeight;
 5     private FrameLayout.LayoutParams frameLayoutParams;
 6     private Activity mActivity;
 7 
 8     private AndroidAdjustResizeBugFix(Activity activity) {
 9         mActivity = activity;
10         FrameLayout content = (FrameLayout) activity.findViewById(android.R.id.content);
11         mChildOfContent = content.getChildAt(0);
12         statusBarHeight = getStatusBarHeight();
13         mChildOfContent.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
14             public void onGlobalLayout() {
15                 possiblyResizeChildOfContent();
16             }
17         });
18         frameLayoutParams = (FrameLayout.LayoutParams) mChildOfContent.getLayoutParams();
19     }
20     public static void assistActivity(Activity activity) {
21         new AndroidAdjustResizeBugFix(activity);
22     }
23     private void possiblyResizeChildOfContent() {
24         int usableHeightNow = computeUsableHeight();
25         if (usableHeightNow != usableHeightPrevious) {
26             int usableHeightSansKeyboard = mChildOfContent.getRootView().getHeight();
27             int heightDifference = usableHeightSansKeyboard - usableHeightNow;
28             if (heightDifference > (usableHeightSansKeyboard / 4)) {
29                 // keyboard probably just became visible
30                 // 若是有高度變化，mChildOfContent.requestLayout()以後界面纔會從新測量
31                 // 這裏就隨便讓原來的高度減去了1
32                 frameLayoutParams.height = usableHeightSansKeyboard - 1;
33             } else {
34                 // keyboard probably just became hidden
35                 frameLayoutParams.height = usableHeightSansKeyboard;
36             }
37             mChildOfContent.requestLayout();
38             usableHeightPrevious = usableHeightNow;
39         }
40     }
41     private int computeUsableHeight() {
42         Rect r = new Rect();
43         mChildOfContent.getWindowVisibleDisplayFrame(r);
44         return r.bottom - r.top + statusBarHeight;
45     }
46     private int getStatusBarHeight() {
47         try {
48             Class<?> c = Class.forName("com.android.internal.R$dimen");
49             Object obj = c.newInstance();
50             Field field = c.getField("status_bar_height");
51             int x = Integer.parseInt(field.get(obj).toString());
52             int dimensionPixelSize = mActivity.getResources().getDimensionPixelSize(x);
53             return dimensionPixelSize;
54         } catch (Exception e) {
55             e.printStackTrace();
56         }
57         return 0;
58     }
59 }