Android监听Home键和Back键的区别介绍

一：android 中home键监听和back键监听的区别：

(1).在android中，当按下home键的时候，默认情况下stop前台的activity，即activity设置成停止状态【onstop()】，而不是销毁状态【ondestory()】。如果再次启动该activity，不是调用oncreate()方法，而是调用onsavedinstancestate方法。则是从onrestart()开始-onstart()-onresume()。
(2).当按下back键则不同，back键默认finish前台的activity，即activity的状态为ondestory为止，再次启动该activity则从oncreate开始，不会调用onsavedinstancestate方法。
总而言之：按下home键会返回桌面，而back则会返回前一个activity。

在这里back键的实现方法就不赘述了，主要讲解一下home键的实现方式吧。以下是我找的参考资料自己思考的。请大家给出建议。
home键监听的实现方法：
(1).在onresum里面注册广播，onpause里面注销广播。
(2).在广播中拦截intent.action_close_system_dialogs 这个action ，通过获取reason字段 来判断长按 还是单击home键。
代码如下：

(1).home键监听封装类：

package com.scd.homewatcher.util;

import android.content.broadcastreceiver;
import android.content.context;
import android.content.intent;
import android.content.intentfilter;
import android.util.log;

/**
 * home键监听封装
 * 
 * @author way
 * 
 */
public class homewatcher {

  // 回调接口
  public interface onhomepressedlistener {

    public void onhomepressed();

    public void onhomelongpressed();
  }

  private static final string tag = "homewatcher";
  /** 上下文 */
  private context mcontext;
  /** 过滤器 */
  private intentfilter mfilter;
  /** 接口 */
  private onhomepressedlistener mlistener;
  /** 广播接收者 */
  private innerrecevier mrecevier;

  public homewatcher(context context) {
    mcontext = context;
    mrecevier = new innerrecevier();
    mfilter = new intentfilter(intent.action_close_system_dialogs);
  }

  /**
   * 设置监听
   * 
   * @param listener
   */
  public void setonhomepressedlistener(onhomepressedlistener listener) {
    mlistener = listener;
  }

  /**
   * 开始监听，注册广播
   */
  public void startwatch() {
    if (mrecevier != null) {
      mcontext.registerreceiver(mrecevier, mfilter);
    }
  }

  /**
   * 停止监听，注销广播
   */
  public void stopwatch() {
    if (mrecevier != null) {
      mcontext.unregisterreceiver(mrecevier);
    }
  }

  /**
   * 广播接收者
   */
  private class innerrecevier extends broadcastreceiver {
    final string system_dialog_reason_key = "reason";
    final string system_dialog_reason_global_actions = "globalactions";
    final string system_dialog_reason_recent_apps = "recentapps";
    final string system_dialog_reason_home_key = "homekey";

    @override
    public void onreceive(context context, intent intent) {
      string action = intent.getaction();
      if (action.equals(intent.action_close_system_dialogs)) {
        string reason = intent.getstringextra(system_dialog_reason_key);
        if (reason != null) {
          log.i(tag, "action:" + action + ",reason:" + reason);
          if (mlistener != null) {
            if (reason.equals(system_dialog_reason_home_key)) {
              // 短按home键
              mlistener.onhomepressed();
            } else if (reason
                .equals(system_dialog_reason_recent_apps)) {
              // 长按home键
              mlistener.onhomelongpressed();
            }
          }
        }
      }
    }
  }
}

(2).mainactivity类：

package com.scd.homewatcher;

import android.app.activity;
import android.os.bundle;
import android.view.keyevent;
import android.widget.toast;

import com.scd.homewatcher.util.homewatcher;
import com.scd.homewatcher.util.homewatcher.onhomepressedlistener;

public class mainactivity extends activity implements onhomepressedlistener {
  private homewatcher mhomewatcher;

  @override
  protected void oncreate(bundle savedinstancestate) {
    super.oncreate(savedinstancestate);
    setcontentview(r.layout.activity_main);

  }

  @override
  protected void onresume() {
    mhomewatcher = new homewatcher(this);
    mhomewatcher.setonhomepressedlistener(this);
    // 注册广播
    mhomewatcher.startwatch();
    super.onresume();
  }

  @override
  protected void onpause() {
    mhomewatcher.setonhomepressedlistener(null);
    // 注销广播
    mhomewatcher.stopwatch();
    super.onpause();
  }

  @override
  public void onhomepressed() {
    // todo
    toast.maketext(this, "短按home键,实现自己的逻辑", toast.length_short).show();

  }

  @override
  public void onhomelongpressed() {
    // todo
    toast.maketext(this, "长按home键,实现自己的逻辑", toast.length_short).show();

  }

  @override
  public boolean onkeydown(int keycode, keyevent event) {
    if ((keycode == keyevent.keycode_back)) {
      system.out.println("按下了back键 onkeydown()");
      return false;
    } else {
      return super.onkeydown(keycode, event);
    }

  }

  @override
  public void onbackpressed() {
    // super.onbackpressed()会自动调用finish()方法,关闭
    super.onbackpressed();
  }

}