Serivce中onRebind被調用的時機很特別,想知道什么時候onRebind被調用,可以接下面的次序來學習,后自然就明白了!
1. 首先要知道,同一個服務既可能被啟動也可以被綁定;
2. Service中onRebind方法被調用,只要符合兩個必要條件就行
<1>服務中onUnBind方法返回值為true<2>服務對象被解綁后沒有被銷毀,之后再次被綁定。下面舉例說明:
例1:同一個Activity對象
先自啟動服務(onCreate, onStartCommand);再綁定服務(onBind); 再解除綁定服務(onUnBind)(由于服務被啟動過,所以Service中onDestroy不會被調用);再綁定服務, 這次綁定的服務對象是之前已經創建好的,所以這次綁定服務時就會調用onReBind方法了,并且本次不會調用onBind方法。
例2:不是同一個Activity對象
打開項目,啟動MainActivity, 在Activity中啟動服務(onCreate, onStartCommand),再綁定服務(onBind); 再解除綁定服務(onUnBind); 再接返回鍵銷毀MainActivity對象(onUnBind);再打開項目啟動MainActivity;再綁定服務,這次綁定服務時會調用onReBind方法
代碼示例:
//activity_main.xml文件
<LinearLayout xmlns:android="//schemas.android.com/apk/res/android"
xmlns:tools="//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>
布局文件運行的界面
//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.點擊按鈕 啟動服務
日志信息: onCreate
2. 點擊按鈕 bind
日志信息: onBind
3.點擊按鈕 unbind
日志信息: onUnBind
4.點擊按鈕 bind
日志信息: onReBind