Android中Home键的监听和拦截示例

2019-12-12 03:44:29

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首先大家应该先了解一种情况，就是Android在应用中是无法拦截Home键的，今天我们带大家看一下Home键的三种情况。

1、在应用中按下Home键的逻辑处理

当我们在应用中按下Home键时界面会启动到桌面，我们在frameworks/base/policy/src/com/android/internal/policy/impl/PhoneWindowManager.Java类中可以看到其实现原理，其不外乎就是调用了以下代码。

  Intent mHomeIntent;  mHomeIntent = new Intent(Intent.ACTION_MAIN, null);  mHomeIntent.addCategory(Intent.CATEGORY_HOME);  mHomeIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED);  startActivity(mHomeIntent);

创建一个启动到桌面的Intent。

2、在应用中监听Home键

在Android应用中如果想监听Home键可以使用广播机制，这个在源码中也有体现。

static public final String SYSTEM_DIALOG_REASON_KEY = "reason";  static public final String SYSTEM_DIALOG_REASON_GLOBAL_ACTIONS = "globalactions";  static public final String SYSTEM_DIALOG_REASON_RECENT_APPS = "recentapps";  static public final String SYSTEM_DIALOG_REASON_HOME_KEY = "homekey";  static public final String SYSTEM_DIALOG_REASON_ASSIST = "assist";  @Override  public void onReceive(Context arg0, Intent arg1) {    String action = arg1.getAction();    //按下Home键会发送ACTION_CLOSE_SYSTEM_DIALOGS的广播    if (action.equals(Intent.ACTION_CLOSE_SYSTEM_DIALOGS)) {      String reason = arg1.getStringExtra(SYSTEM_DIALOG_REASON_KEY);      if (reason != null) {        if (reason.equals(SYSTEM_DIALOG_REASON_HOME_KEY)) {          // 短按home键          Toast.makeText(arg0, "短按Home键", Toast.LENGTH_SHORT).show();        } else if (reason.equals(SYSTEM_DIALOG_REASON_RECENT_APPS)) {          // RECENT_APPS键          Toast.makeText(arg0, "RECENT_APPS", Toast.LENGTH_SHORT).show();        }      }    }  }

这样就可以监听Home的是否被按下。

3、在Frameworks层拦截Home键

在frameworks/base/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java文件中我们首先看一下interceptKeyBeforeDispatching()方法。

public long interceptKeyBeforeDispatching(WindowState win, KeyEvent event, int policyFlags) {  //......  if (keyCode == KeyEvent.KEYCODE_HOME) {    //......    handleShortPressOnHome();  }}//进入handleShortPressOnHomeprivate void handleShortPressOnHome() {    // If there's a dream running then use home to escape the dream    // but don't actually go home.    if (mDreamManagerInternal != null && mDreamManagerInternal.isDreaming()) {      mDreamManagerInternal.stopDream(false /*immediate*/);      return;    }    // Go home!    launchHomeFromHotKey();  }

进入launchHomeFromHotKey方法。

static public final String SYSTEM_DIALOG_REASON_KEY = "reason";  static public final String SYSTEM_DIALOG_REASON_GLOBAL_ACTIONS = "globalactions";  static public final String SYSTEM_DIALOG_REASON_RECENT_APPS = "recentapps";  static public final String SYSTEM_DIALOG_REASON_HOME_KEY = "homekey";  static public final String SYSTEM_DIALOG_REASON_ASSIST = "assist";void launchHomeFromHotKey() {    if (isKeyguardShowingAndNotOccluded()) {      // don't launch home if keyguard showing    } else if (!mHideLockScreen && mKeyguardDelegate.isInputRestricted()) {      // when in keyguard restricted mode, must first verify unlock      // before launching home      mKeyguardDelegate.verifyUnlock(new OnKeyguardExitResult() {        @Override        public void onKeyguardExitResult(boolean success) {          if (success) {            try {              ActivityManagerNative.getDefault().stopAppSwitches();            } catch (RemoteException e) {            }            sendCloseSystemWindows(SYSTEM_DIALOG_REASON_HOME_KEY);            startDockOrHome();          }        }      });    } else {      // no keyguard stuff to worry about, just launch home!      try {        ActivityManagerNative.getDefault().stopAppSwitches();      } catch (RemoteException e) {      }      if (mRecentsVisible) {        // Hide Recents and notify it to launch Home        awakenDreams();        sendCloseSystemWindows(SYSTEM_DIALOG_REASON_HOME_KEY);        hideRecentApps(false, true);      } else {        // Otherwise, just launch Home        sendCloseSystemWindows(SYSTEM_DIALOG_REASON_HOME_KEY);        //启动Launcher界面        startDockOrHome();      }    }  }

以上方法可处理Home键的拦截操作，接下来我们进入startDockOrHome方法。

void startDockOrHome() {    if (OptConfig.LC_RAM_SUPPORT) {      try {        ActivityManagerNative.getDefault().startHomePre();      } catch (RemoteException re) {      }    }    awakenDreams();    Intent dock = createHomeDockIntent();    if (dock != null) {      try {        startActivityAsUser(dock, UserHandle.CURRENT);        return;      } catch (ActivityNotFoundException e) {      }    }    //intent的相关设置    mHomeIntent = new Intent(Intent.ACTION_MAIN, null);    mHomeIntent.addCategory(Intent.CATEGORY_HOME);    mHomeIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK        | Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED);    startActivityAsUser(mHomeIntent, UserHandle.CURRENT);  }

好啦，这里就对Home键进行简单的监听和拦截。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持武林网。

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