Android开发之Service与多个Activity通信

　由于项目需要，我们有时候需要在service中处理耗时操作，然后将结果发送给activity以更新状态。通常情况下，我们只需要在一个service与一个activity之间通信，通常这种情况下，我们使用最多的是通过回调接口。具体做法是在service中定义一个接口，在activity中实现该接口，并通过bindservice来传入。实现方式很简单，在此不再赘述。

　　当需要将service中的结果一次发送给多个activity时，我们又该如何实现呢？经过多个项目的积累，总结了三种实现的方式。分别是回调接口、广播接收者和观察者模式。

1.回调接口的方式，与单个service与单个activity通信类似，只是将service中的接口变为接口的集合，每个需要通信的activity都实现接口，然后在获取结果后，循环调用集合中的实现类，来与多个activity进行通信，代码如下：

Service类：

package com.example.servicecallback;import java.util.ArrayList;import java.util.List;import android.app.Service;import android.content.Intent;import android.os.Binder;import android.os.Handler;import android.os.IBinder;import android.os.Message;import android.util.Log;public class ContentService extends Service {    //回调接口的集合    private List<Callback> list;    @Override    public IBinder onBind(Intent arg0) {        // TODO Auto-generated method stub        return new LocalBinder();    }    @Override    public void onCreate() {        // TODO Auto-generated method stub        super.onCreate();        list = new ArrayList<Callback>();    }    public final class LocalBinder extends Binder {        public ContentService getService() {            return ContentService.this;        }    }    /**     * 回调接口     * @author Ivan Xu     *     */    public interface Callback {        public void getPerson(Person person);    }    /**     * 往回调接口集合中添加一个实现类     * @param callback     */    public void addCallback(Callback callback) {        list.add(callback);    }    public void asyncSendPerson(final String name) {        // 休息5秒，模拟异步任务        new Thread(new Runnable() {            @Override            public void run() {                // TODO Auto-generated method stub                try {                    Thread.sleep(5000);                } catch (InterruptedException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                }                handler.sendMessage(handler.obtainMessage(0, name));            }        }).start();    }    private Handler handler = new Handler() {        @Override        public void handleMessage(Message msg) {            // TODO Auto-generated method stub            String name = (String) msg.obj;            Log.i("ContentService", "---name-->" + name);            Person person = new Person();            person.setName(name);            Log.i("ContentService", "---list.size()-->" + list.size());            Log.i("ContentService", "---person-->" + person.toString());            //遍历集合，通知所有的实现类，即activity            for (int i = 0; i < list.size(); i++) {                list.get(i).getPerson(person);            }        }    };}

第一个activity：

package com.example.servicecallback;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.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.TextView;import com.example.servicecallback.ContentService.Callback;import com.example.servicecallback.ContentService.LocalBinder;public class MainActivity extends Activity implements Callback {    private MyServiceConn conn;    private ContentService service;    private TextView mContent;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        conn=new MyServiceConn();        bindService(new Intent(this, ContentService.class), conn,                BIND_AUTO_CREATE);        mContent = (TextView) findViewById(R.id.content);        this.findViewById(R.id.button1).setOnClickListener(                new OnClickListener() {                    @Override                    public void onClick(View v) {                        // TODO Auto-generated method stub                        startActivity(new Intent(MainActivity.this,                                OtherActivity.class));                    }                });    }    @Override    public boolean onCreateOptionsMenu(Menu menu) {        // Inflate the menu; this adds items to the action bar if it is present.        getMenuInflater().inflate(R.menu.main, menu);        return true;    }    public class MyServiceConn implements ServiceConnection {        @Override        public void onServiceConnected(ComponentName name, IBinder binder) {            service = ((LocalBinder) binder).getService();            //将当前activity添加到接口集合中            service.addCallback(MainActivity.this);        }        @Override        public void onServiceDisconnected(ComponentName name) {            // TODO Auto-generated method stub            service = null;        }    }    @Override    protected void onDestroy() {        // TODO Auto-generated method stub        super.onDestroy();        unbindService(conn);    }    /**     * 获取回调的内容，更新UI     */    @Override    public void getPerson(Person person) {        // TODO Auto-generated method stub        mContent.setText(person.toString());    }}

第二个activity：

package com.example.servicecallback;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.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;import com.example.servicecallback.ContentService.Callback;import com.example.servicecallback.ContentService.LocalBinder;import com.example.servicecallback.MainActivity.MyServiceConn;public class OtherActivity extends Activity implements Callback {    private ContentService service;    private TextView mContent;    private Button mSubmit;    private EditText mEditText;    private ServiceConnection conn;    @Override    protected void onCreate(Bundle savedInstanceState) {        // TODO Auto-generated method stub        super.onCreate(savedInstanceState);        setContentView(R.layout.other);        mEditText = (EditText) findViewById(R.id.edittext);        mSubmit = (Button) findViewById(R.id.button1);        mContent = (TextView) findViewById(R.id.content);        mSubmit.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                // TODO Auto-generated method stub                String name = mEditText.getText().toString();                service.asyncSendPerson(name);            }        });                conn=new MyServiceConn();        bindService(new Intent(OtherActivity.this, ContentService.class), conn,                BIND_AUTO_CREATE);    }    public final class MyServiceConn implements ServiceConnection {        @Override        public void onServiceConnected(ComponentName name, IBinder binder) {            // TODO Auto-generated method stub            service = ((LocalBinder) binder).getService();            //将当前activity添加到接口集合中            service.addCallback(OtherActivity.this);        }        @Override        public void onServiceDisconnected(ComponentName name) {            // TODO Auto-generated method stub            service = null;        }    }    @Override    protected void onDestroy() {        // TODO Auto-generated method stub        super.onDestroy();        unbindService(conn);    }    /**     * 获取回调的内容，更新UI     */    @Override    public void getPerson(Person person) {        // TODO Auto-generated method stub        mContent.setText(person.toString());    }}

 

2.通过广播接收者，在service中执行完耗时操作后，将结果以广播的形式发送，在所有的activity中注册广播，接收到结果后更新UI，这种方式比较简单，也是笔者比较推荐的方式。因为耗时的操作结果不需要以handler的方式发送到主线程，可以直接在子线程中发送广播，接收者始终运行在主线程中。代码如下：

Service类：

package com.example.servicecallback;import android.app.Service;import android.content.Intent;import android.os.Binder;import android.os.IBinder;public class ContentService extends Service {    @Override    public IBinder onBind(Intent arg0) {        // TODO Auto-generated method stub        return new LocalBinder();    }    @Override    public void onCreate() {        // TODO Auto-generated method stub        super.onCreate();    }    public final class LocalBinder extends Binder {        public ContentService getService() {            return ContentService.this;        }    }    public void asyncSendPerson(final String name) {        // 休息5秒，模拟异步任务        new Thread(new Runnable() {            @Override            public void run() {                try {                    Thread.sleep(5000);                } catch (InterruptedException e) {                    e.printStackTrace();                }                //可以在子线程中直接发送广播                sendContentBroadcast(name);            }        }).start();    }    /**     * 发送广播     * @param name     */    protected void sendContentBroadcast(String name) {        // TODO Auto-generated method stub        Intent intent=new Intent();        intent.setAction("com.example.servicecallback.content");        intent.putExtra("name", name);        sendBroadcast(intent);    }}

第一个activity：

package com.example.servicecallback;import android.app.Activity;import android.content.BroadcastReceiver;import android.content.ComponentName;import android.content.Context;import android.content.Intent;import android.content.IntentFilter;import android.content.ServiceConnection;import android.os.Bundle;import android.os.IBinder;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.TextView;public class MainActivity extends Activity {    private MyServiceConn conn;    private TextView mContent;    private ContentReceiver mReceiver;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        conn = new MyServiceConn();        bindService(new Intent(this, ContentService.class), conn,                BIND_AUTO_CREATE);        mContent = (TextView) findViewById(R.id.content);        this.findViewById(R.id.button1).setOnClickListener(                new OnClickListener() {                    @Override                    public void onClick(View v) {                        // TODO Auto-generated method stub                        startActivity(new Intent(MainActivity.this,                                OtherActivity.class));                    }                });                doRegisterReceiver();    }    /**     * 注册广播接收者     */    private void doRegisterReceiver() {        mReceiver=new ContentReceiver();        IntentFilter filter = new IntentFilter(                "com.example.servicecallback.content");        registerReceiver(mReceiver, filter);    }    @Override    public boolean onCreateOptionsMenu(Menu menu) {        // Inflate the menu; this adds items to the action bar if it is present.        getMenuInflater().inflate(R.menu.main, menu);        return true;    }    public class MyServiceConn implements ServiceConnection {        @Override        public void onServiceConnected(ComponentName name, IBinder binder) {            // service = ((LocalBinder) binder).getService();        }        @Override        public void onServiceDisconnected(ComponentName name) {            // TODO Auto-generated method stub            // service = null;        }    }    @Override    protected void onDestroy() {        // TODO Auto-generated method stub        super.onDestroy();        unbindService(conn);        if (mReceiver!=null) {            unregisterReceiver(mReceiver);        }    }    public class ContentReceiver extends BroadcastReceiver {        @Override        public void onReceive(Context context, Intent intent) {            String name = intent.getStringExtra("name");            Person person = new Person();            person.setName(name);            mContent.setText(person.toString());        }    }}

另一个activity：

package com.example.servicecallback;import android.app.Activity;import android.content.BroadcastReceiver;import android.content.ComponentName;import android.content.Context;import android.content.Intent;import android.content.IntentFilter;import android.content.ServiceConnection;import android.os.Bundle;import android.os.IBinder;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;import com.example.servicecallback.ContentService.LocalBinder;public class OtherActivity extends Activity {    private ContentService service;    private TextView mContent;    private Button mSubmit;    private EditText mEditText;    private ServiceConnection conn;    private ContentReceiver mReceiver;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.other);        mEditText = (EditText) findViewById(R.id.edittext);        mSubmit = (Button) findViewById(R.id.button1);        mContent = (TextView) findViewById(R.id.content);        mSubmit.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                String name = mEditText.getText().toString();                service.asyncSendPerson(name);            }        });                conn=new MyServiceConn();        bindService(new Intent(OtherActivity.this, ContentService.class), conn,                BIND_AUTO_CREATE);        doRegisterReceiver();    }    private void doRegisterReceiver() {        mReceiver=new ContentReceiver();        IntentFilter filter = new IntentFilter(                "com.example.servicecallback.content");        registerReceiver(mReceiver, filter);    }        public final class MyServiceConn implements ServiceConnection {        @Override        public void onServiceConnected(ComponentName name, IBinder binder) {            service = ((LocalBinder) binder).getService();        }        @Override        public void onServiceDisconnected(ComponentName name) {            service = null;        }    }    @Override    protected void onDestroy() {        super.onDestroy();        unbindService(conn);        if (mReceiver!=null) {            unregisterReceiver(mReceiver);        }    }    public class ContentReceiver extends BroadcastReceiver {        @Override        public void onReceive(Context context, Intent intent) {            String name = intent.getStringExtra("name");            Person person = new Person();            person.setName(name);            mContent.setText(person.toString());        }    }}

 

3.使用观察者模式，service为被观察者，所有的activity为观察者，当service中的内容发生改变时，通知所有的activity来更新，代码如下：

Service类：

package com.example.servicecallback;import java.util.Observable;import java.util.Observer;import android.app.Service;import android.content.Intent;import android.os.Binder;import android.os.Handler;import android.os.IBinder;import android.os.Message;public class ContentService extends Service {    //被观察者    private MyObservable mObservable;    @Override    public IBinder onBind(Intent arg0) {        return new LocalBinder();    }    @Override    public void onCreate() {        super.onCreate();        mObservable = new MyObservable();    }    public final class LocalBinder extends Binder {        public ContentService getService() {            return ContentService.this;        }    }    public void asyncSendPerson(final String name) {        // 休息5秒，模拟异步任务        new Thread(new Runnable() {            @Override            public void run() {                try {                    Thread.sleep(5000);                } catch (InterruptedException e) {                    e.printStackTrace();                }                handler.sendMessage(handler.obtainMessage(0, name));            }        }).start();    }    /**     * 添加观察者     * @param observer     */    public void addObserver(Observer observer) {        mObservable.addObserver(observer);    }    private Handler handler = new Handler() {        @Override        public void handleMessage(Message msg) {            String name = (String) msg.obj;            Person person = new Person();            person.setName(name);            //通知更新            mObservable.notifyChanged(person);        }    };    public class MyObservable extends Observable {                public void notifyChanged(Object object) {            this.setChanged();            this.notifyObservers(object);        }    }}

第一个activity：

package com.example.servicecallback;import java.util.Observable;import java.util.Observer;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.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.TextView;import com.example.servicecallback.ContentService.LocalBinder;public class MainActivity extends Activity implements Observer {    private MyServiceConn conn;    private TextView mContent;    private ContentService mService;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        conn = new MyServiceConn();        bindService(new Intent(this, ContentService.class), conn,                BIND_AUTO_CREATE);        mContent = (TextView) findViewById(R.id.content);        this.findViewById(R.id.button1).setOnClickListener(                new OnClickListener() {                    @Override                    public void onClick(View v) {                        startActivity(new Intent(MainActivity.this,                                OtherActivity.class));                    }                });    }    @Override    public boolean onCreateOptionsMenu(Menu menu) {        getMenuInflater().inflate(R.menu.main, menu);        return true;    }    public class MyServiceConn implements ServiceConnection {        @Override        public void onServiceConnected(ComponentName name, IBinder binder) {            mService = ((LocalBinder) binder).getService();            //将当前activity添加为观察者            mService.addObserver(MainActivity.this);        }        @Override        public void onServiceDisconnected(ComponentName name) {            mService = null;        }    }    @Override    protected void onDestroy() {        super.onDestroy();        unbindService(conn);    }    //更新UI    @Override    public void update(Observable observable, Object data) {        Person person = (Person) data;        mContent.setText(person.toString());    }}

第二个activity：

package com.example.servicecallback;import java.util.Observable;import java.util.Observer;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.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;import com.example.servicecallback.ContentService.LocalBinder;public class OtherActivity extends Activity implements Observer {    private ContentService service;    private TextView mContent;    private Button mSubmit;    private EditText mEditText;    private ServiceConnection conn;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.other);        mEditText = (EditText) findViewById(R.id.edittext);        mSubmit = (Button) findViewById(R.id.button1);        mContent = (TextView) findViewById(R.id.content);        mSubmit.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                String name = mEditText.getText().toString();                service.asyncSendPerson(name);            }        });        conn = new MyServiceConn();        bindService(new Intent(OtherActivity.this, ContentService.class), conn,                BIND_AUTO_CREATE);    }    public final class MyServiceConn implements ServiceConnection {        @Override        public void onServiceConnected(ComponentName name, IBinder binder) {            service = ((LocalBinder) binder).getService();            //将当前activity添加为观察者            service.addObserver(OtherActivity.this);        }        @Override        public void onServiceDisconnected(ComponentName name) {            service = null;        }    }    @Override    protected void onDestroy() {        super.onDestroy();        unbindService(conn);    }    //更新UI    @Override    public void update(Observable observable, Object data) {        // TODO Auto-generated method stub        Person person=(Person) data;                mContent.setText(person.toString());    }}

 

附上其他相关代码，三种方式都一样：

Person类：

package com.example.servicecallback;public class Person {    private String name;    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    @Override    public String toString() {        return "Person [name=" + name + "]";    }}

MainActiivty的布局文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context=".MainActivity" >    <Button        android:id="@+id/button1"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="next" />    <TextView        android:id="@+id/content"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="@string/hello_world" /></LinearLayout>

OtherActivity的布局文件：

View Code

由于笔者的水平有限，如有错漏，请各位留言指正，感激不尽！