绑定本地Service并与之通信

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当程序通过startService()和stopService()启动、关闭Service时，Service与访问者之间基本上不存在太多的关联，一次Service和访问者之间无法进行通信和数据传递。

如果Service和访问者之间需要进行方法调用或数据传递，则使用bindService()和unbindService()方法启动、关闭服务。

Context的bindService()方法的完整方法签名为：

bindService(Intent service, ServiceConnection conn, int flags)

三个参数用法如下：

1.service：通过Intent指定要启动的Service。

2.conn：该参数是一个ServiceConnection对象，用于监听访问者与Service之间的连接情况。连接成功时，将回调该对象的onServiceConnected(ComponentName name, IBinder service)方法；当断开连接时，回调该对象的onServiceDisconnected(ComponentName name)方法。

3.flags：指定绑定时是否自动创建Service（如果Service还未创建）。0为不自动创建，BIND_AUTO_CREATE为自动创建。

注意到ServiceConnection对象的onServiceConnected方法中有一个IBinder对象，该对象实现与被绑定Service之间的通信。

下面给出一个实例：

工程结构：

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.example.leidong.bindservice">    <application        android:allowBackup="true"        android:icon="@mipmap/ic_launcher"        android:label="@string/app_name"        android:supportsRtl="true"        android:theme="@style/AppTheme">        <activity android:name=".MainActivity">            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>        <service android:name=".BindService">        </service>    </application></manifest>

main.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout    xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:background="#2b2b2b">    <!--bind按钮-->    <Button        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:layout_marginLeft="5pt"        android:layout_marginRight="5pt"        android:layout_marginTop="10pt"        android:text="B I N D"        android:textColor="#ffffff"        android:textStyle="bold"        android:background="#696969"        android:id="@+id/bindButton"        android:layout_gravity="center_horizontal" />    <!--unbind按钮-->    <Button        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:layout_marginLeft="5pt"        android:layout_marginRight="5pt"        android:layout_marginTop="10pt"        android:text="U N B I N D"        android:textColor="#ffffff"        android:textStyle="bold"        android:background="#696969"        android:id="@+id/unbindButton"        android:layout_gravity="center_horizontal" />    <!--getServiceStatus按钮-->    <Button        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:layout_marginLeft="5pt"        android:layout_marginRight="5pt"        android:layout_marginTop="10pt"        android:text="G E T    S E R V I C E    S T A T U S"        android:textColor="#ffffff"        android:textStyle="bold"        android:background="#696969"        android:id="@+id/getServiceStatusButton"        android:layout_gravity="center_horizontal" /></LinearLayout>

MainActivity.java

package com.example.leidong.bindservice;import android.app.Activity;import android.content.ComponentName;import android.content.Intent;import android.content.ServiceConnection;import android.os.Bundle;import android.os.IBinder;import android.view.View;import android.widget.Button;import android.widget.Toast;/** * Created by Lei Dong on 2016/9/5. */public class MainActivity extends Activity {    //声明按钮    Button bind;    Button unbind;    Button getServiceStatus;    //保持所启动的Service的IBinder对象    BindService.MyBinder myBinder;    //定义一个ServiceConnection对象    private ServiceConnection connection = new ServiceConnection() {        //连接成功时        @Override        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {            System.out.println("~~~~~Connected~~~~~");            //获取Service的onBind方法返回的MyBinder对象            myBinder = (BindService.MyBinder) iBinder;        }        //连接失败时        @Override        public void onServiceDisconnected(ComponentName componentName) {            System.out.println("~~~~~Disconnected~~~~~");        }    };    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        //获取程序界面中的bind、unbind、getServiceStatus按钮        bind = (Button)findViewById(R.id.bindButton);        unbind = (Button)findViewById(R.id.unbindButton);        getServiceStatus = (Button)findViewById(R.id.getServiceStatusButton);        //创建启动Service的Intent        final Intent intent = new Intent(MainActivity.this, BindService.class);        //监听bind按钮点击        bind.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                //绑定指定Service                bindService(intent, connection, BIND_AUTO_CREATE);            }        });        //监听unbind按钮点击        unbind.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                //解除绑定Service                unbindService(connection);            }        });        //监听getServiceStatus按钮点击        getServiceStatus.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                //获取并显示Service的count值                Toast.makeText(MainActivity.this,                        "Service的count值为：" + myBinder.getCount(),                        Toast.LENGTH_SHORT).show();            }        });    }}

BindService.java

package com.example.leidong.bindservice;import android.app.Service;import android.content.Intent;import android.os.Binder;import android.os.IBinder;import android.support.annotation.Nullable;/** * Created by Lei Dong on 2016/9/5. */public class BindService extends Service {    private int count;    private boolean quitFlag;    //定义onBinder方法所返回的对象    private MyBinder myBinder = new MyBinder();    //通过继承Binder来实现IBinder类    public class MyBinder extends Binder {        public int getCount(){            //获取Service的运行状态            return count;        }    }    @Nullable    @Override    public IBinder onBind(Intent intent) {        System.out.println("~~~~~Service is binded~~~~~");        //返回IBinder对象        return myBinder;    }    @Override    public void onCreate(){        super.onCreate();        System.out.println("~~~~~Service is created~~~~~");        //启动一条线程，动态地修改count状态值        new Thread(){            @Override            public void run(){                while(!quitFlag){                    try{                        Thread.sleep(1000);                    }catch (InterruptedException e)                    {                    }                    count++;                }            }        }.start();    }    //Service被断开连接时回调该方法    @Override    public boolean onUnbind(Intent intent){        System.out.println("~~~~~Service is unbinded~~~~~");        return true;    }    //Service被关闭之前回调    @Override    public void onDestroy(){        super.onDestroy();        this.quitFlag = true;        System.out.println("~~~~~Service is destroyed~~~~~");    }}

AVD效果：

点击BIND按钮，LogCat效果：

点击UNBIND按钮，LogCat效果：

点击GET SERVICE STATUS按钮，LogCat效果：

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