利用广播调用后台服务方法并根据方法返回的内容更新UI

一、UI布局代码

<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.shz.localservice.MainActivity"
    tools:ignore="MergeRootFrame" >

    
    <EditText 
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="请输入电影票Id"
        android:id="@+id/txtTicketId"/>
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="callServiceMethod"
        android:text="查询" />
    
    <TextView 
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/lblTicketInfo"
        android:textColor="#ff0000"/>

</LinearLayout>

二、MainActivity代码

package com.shz.localservice;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import com.shz.callservicebybroadcastreceiver.R;

public class MainActivity extends Activity {

    /**
     * 通过广播调用后台服务并更新UI 实现步骤：
     * 1.前台Activity发出一个自定义广播A（Action：com.shz.getticketinfo），后台服务需注册该广播A进行监听。
     * 2.后台服务监听到该广播A之后
     * ，调用自己内部方法获取电影票信息，并发出一个自定义广播B（Action：com.shz.sendticketinfo）。
     * 3.前台Activity需注册该广播B进行监听，获取广播B中的内容更新UI。
     */

    private EditText txtTicketId;
    private TextView lblTicketInfo;
    private ReceiveTicketInfoReceiver receiver;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        txtTicketId = (EditText) findViewById(R.id.txtTicketId);
        lblTicketInfo = (TextView) findViewById(R.id.lblTicketInfo);

        // 开启服务
        Intent intent = new Intent(this, TicketService.class);
        startService(intent);

        // 注册后台服务发出的广播，该广播包含电影票信息
        receiver = new ReceiveTicketInfoReceiver();
        IntentFilter filter = new IntentFilter("com.shz.sendticketinfo");
        registerReceiver(receiver, filter);
    }

    /**
     * 该接收者用于监听后台服务发送出的广播B，并更新UI
     * 
     * @author SHZ
     * 
     */
    private class ReceiveTicketInfoReceiver extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, Intent intent) {
            String ticketInfo = intent.getStringExtra("TicketInfo");
            lblTicketInfo.setText(ticketInfo);
        }

    }

    public void callServiceMethod(View view) {
        String strTicketId = this.txtTicketId.getText().toString().trim();
        if(TextUtils.isEmpty(strTicketId))
        {
            Toast.makeText(this, "请输入电影票Id", 1).show();
            return;
        }
        
        // 发送一个自定义广播，后台服务会监听该广播，并调用服务方法获取电影票信息
        Intent intent = new Intent();
        intent.setAction("com.shz.getticketinfo");
        intent.putExtra("TicketId", Integer.parseInt(strTicketId));
        sendBroadcast(intent);        
    }

    @Override
    protected void onDestroy() {
        unregisterReceiver(receiver);
        stopService(new Intent(this, TicketService.class));
        super.onDestroy();
    }
}

三、服务代码

package com.shz.localservice;

import java.util.ArrayList;
import java.util.List;

import android.app.Service;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.IBinder;
import android.util.Log;

/**
 * 后台服务（组件），提供查询电影票相关信息
 * @author SHZ
 *
 */
public class TicketService extends Service {

    private final static String TAG = "TicketService";
    private List<Ticket> tickets;
    private SendTicketInfoReceiver receiver;
    
    @Override
    public IBinder onBind(Intent intent) {
        Log.i(TAG, "onBind 服务绑定成功");
        return null;
    }

    @Override
    public void onCreate() {        
        super.onCreate();
        Log.i(TAG, "onCreate 服务创建成功");
        this.tickets = new ArrayList<Ticket>();
        this.tickets.add(new Ticket(1, "变形金刚4", 103));
        this.tickets.add(new Ticket(2, "窃听风云3", 86));
        this.tickets.add(new Ticket(3, "反腐风暴", 75));
        
        // 注册前台Activity发出的广播，该广播是请求电影票信息
        receiver = new SendTicketInfoReceiver();
        IntentFilter filter = new IntentFilter("com.shz.getticketinfo");
        registerReceiver(receiver, filter);
    }


    @Override
    public void onDestroy() {
        super.onDestroy();
        Log.i(TAG, "onDestroy 服务销毁成功");
        unregisterReceiver(receiver);
    }
    
    private Ticket getTicket(int id)
    {
        for(Ticket ticket:this.tickets)
        {
            if(ticket.Id == id)
            {
                return ticket;
            }
        }
        
        return null;
    }
    
    /**
     * 服务内部方法：查询电影票信息
     * @param id 
     * @return
     */
    public String getTicketInfo(int id)
    {
        Ticket ticket = this.getTicket(id);
        if(ticket == null)
        {
            return "未查询到该电影票信息";
        }
        else
        {
            return ticket.toString();
        }
    }
    
    /**
     * 服务内部方法（测试用，没有意义）：更新电影票价格
     * @param id
     * @param newPrice
     */
    public void updateTicketPrice(int id, float newPrice)
    {
        Ticket ticket = this.getTicket(id);
        if(ticket != null)
        {
            ticket.Price = newPrice;
        }
    }
    
    /**
     * 该接收者用于接收前台Activity发出的广播A，获取A中的TicketId，调用内部方法查询电影票信息，并发出广播B
     * @author SHZ
     *
     */
    private class SendTicketInfoReceiver extends BroadcastReceiver
    {

        @Override
        public void onReceive(Context context, Intent intent) {
            int ticketId = intent.getIntExtra("TicketId", 0);
            String ticketInfo = getTicketInfo(ticketId);
            
            // 发送本服务的一个自定义广播，前台Activity会监听该广播获取电影票信息
            Intent sendIntent = new Intent();
            sendIntent.setAction("com.shz.sendticketinfo");
            sendIntent.putExtra("TicketInfo", ticketInfo);
            sendBroadcast(sendIntent);
        }
        
    }

}

四、其他相关代码

package com.shz.localservice;

public class Ticket {
    public int Id;
    public String Name;
    public float Price;
    
    public Ticket(int id, String name, float price) {
        Id = id;
        Name = name;
        Price = price;
    }
    
    @Override
    public String toString() {
        return "您查询的电影是："+this.Name+"，票价为："+this.Price;
    }
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.shz.callservicebybroadcastreceiver"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="19" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.shz.localservice.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <service android:name="com.shz.localservice.TicketService"></service>
    </application>

</manifest>

效果截图：