Android中Home键的监听和拦截示例

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handleshortpressonhome
private 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。