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：