Serivce中onRebind被调用的时机很特别,想知道什么时候onRebind被调用,可以接下面的次序来学习,最后自然就明白了!
1. 首先要知道,同一个服务既可能被启动也可以被绑定;
2. Service中onRebind方法被调用,只要符合两个必要条件就行
(1)服务中onUnBind方法返回值为true
(2)服务对象被解绑后没有被销毁,之后再次被绑定
。下面举例说明:
例1:同一个Activity对象
先自启动服务(onCreate, onStartCommand);再绑定服务(onBind); 再解除绑定服务(onUnBind)(由于服务被启动过,所以Service中onDestroy不会被调用);再绑定服务, 这次绑定的服务对象是之前已经创建好的,所以这次绑定服务时就会调用onReBind方法了,并且本次不会调用onBind方法。
例2:不是同一个Activity对象
打开项目,启动MainActivity, 在Activity中启动服务(onCreate, onStartCommand),再绑定服务(onBind); 再解除绑定服务(onUnBind); 再接返回键销毁MainActivity对象(onUnBind);再打开项目启动MainActivity;再绑定服务,这次绑定服务时会调用onReBind方法
代码示例:
activity_main.xml文件
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/container" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context="com.qf.act.MainActivity" tools:ignore="MergeRootFrame,Orientation" > <TextView android:id="@+id/textView1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="TextView1" /> <Button android:id="@+id/bind" android:layout_width="wrap_content" android:layout_height="wrap_content" android:onClick="work" android:text="bind" /> <Button android:id="@+id/unbind" android:layout_width="wrap_content" android:layout_height="wrap_content" android:onClick="work" android:text="unbind" /> <Button android:id="@+id/call" android:layout_width="wrap_content" android:layout_height="wrap_content" android:onClick="work" android:text="call" /> </LinearLayout>
LocalService.java文件
package com.qf.act; import android.app.Service; import android.content.Intent; import android.os.Binder; import android.os.IBinder; import android.util.Log; public class LocalService extends Service { private static String LOG = "LocalService"; private int count = 0; private IBinder binder = new MyIbinder(); @Override public IBinder onBind(Intent intent) { Log.e(LOG, "onBind"); return this.binder; } @Override public boolean onUnbind(Intent intent) { Log.e(LOG, "onUnBind"); return true; } @Override public void onRebind(Intent intent) { super.onRebind(intent); Log.e(LOG, "onRebind"); } @Override public void onCreate() { new Thread() { public void run() { Log.e(LOG, "onCreate"); for (int i = 0; i < 100; i++) { count++; try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } } }.start(); super.onCreate(); } public class MyIbinder extends Binder { public int getCount() { return LocalService.this.getCount(); } } public int getCount() { return this.count; } @Override public void onDestroy() { Log.e(LOG, "onDestroy"); super.onDestroy(); } }
MainActivity.java文件
package com.qf.act; import com.qf.act.LocalService.MyIbinder; import android.app.Activity; import android.app.Service; import android.content.ComponentName; import android.content.Intent; import android.content.ServiceConnection; import android.os.Bundle; import android.os.IBinder; import android.util.Log; import android.view.View; import android.widget.Toast; public class MainActivity extends Activity { private boolean isBind = false; private LocalService.MyIbinder binder = null; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } public void work(View v) { Intent intent = new Intent(); intent.setClass(this, LocalService.class); switch (v.getId()) { case R.id.start: this.startService(intent); break; case R.id.stop: this.stopService(intent); break; case R.id.bind: this.bindService(intent, conn, Service.BIND_AUTO_CREATE); break; case R.id.unbind: if(isBind == true) { unbindService(conn); isBind = false; } break; case R.id.call: if(this.binder == null) return; int count = this.binder.getCount(); Toast.makeText(this, ""+count, 1).show(); break; } } private ServiceConnection conn = new ServiceConnection() { @Override public void onServiceDisconnected(ComponentName name) { Log.e("", "onServiceDisconnected"); } @Override public void onServiceConnected(ComponentName name, IBinder service) { binder = (MyIbinder) service; isBind = true; } }; }
操作示例:
1.点击按钮 启动服务
日志信息: onCreate
2. 点击按钮 bind
日志信息: onBind
3.点击按钮 unbind
日志信息: onUnBind
4.点击按钮 bind
日志信息: onReBind