Activity与Service交互（使用广播方式）

近期学习到了Activity与Service进行交互的过程，在此记录。本次使用的Activity和Service交互的方式是通过广播。

下面是完成后的效果：

完成效果图

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:padding="10dp"
    tools:context="linchange.com.activityservice.MainActivity">

    <Button
        android:id="@+id/button"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="下载"/>

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="100dp"
        android:gravity="center"
        android:textSize="18sp"
        android:text="0%" />

    <ProgressBar
        android:id="@+id/progressBar"
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:max="100"/>
    

</LinearLayout>

MainActivity.java

package linchange.com.activityservice;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    private Button button; //按钮
    private TextView textView; //进度提示文字
    private ProgressBar progressBar; //进度条
    private int count = 0; //计数器
    private Intent serviceIntent; //服务意图
    private CounterReceiver counterReceiver; //广播接收者
    private IntentFilter intentFilter; //意图过滤器

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

        button = (Button) findViewById(R.id.button); //绑定按钮
        textView = (TextView) findViewById(R.id.textView); //进度提示文字
        progressBar = (ProgressBar) findViewById(R.id.progressBar); //绑定进度条

        //初始化服务意图
        serviceIntent = new Intent(MainActivity.this, CounterService.class);

        counterReceiver = new CounterReceiver(); //初始化次数接收者
        intentFilter = new IntentFilter(); //初始化意图过滤器
        intentFilter.addAction(CounterService.ACTION_NAME); //添加动作

        registerReceiver(counterReceiver, intentFilter); //注册广播

        button.setOnClickListener(new View.OnClickListener() { //设置点击事件
            @Override
            public void onClick(View v) {
                serviceIntent.putExtra(CounterService.COUNTER, count); //存放数据到intent
                startService(serviceIntent); //启动服务
            }
        });
    }

    //次数接收者
    class CounterReceiver extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, final Intent intent) {
            runOnUiThread(new Runnable() { //运行在主线程
                @Override
                public void run() {
                    //从intent中获取计数次数
                    count = intent.getIntExtra(CounterService.COUNTER, 2000);
                    textView.setText(String.valueOf(count + "%"));
                    //设置进度条的进度
                    progressBar.setProgress(count);
                }
            });
        }
    }

    @Override
    protected void onDestroy() {
        stopService(serviceIntent); //停止服务
        unregisterReceiver(counterReceiver); //解除注册次数接收者
        super.onDestroy();
    }
}

CounterService.java

package linchange.com.activityservice;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.support.annotation.Nullable;

/**
 * Created by lkmc2 on 2018/1/11.
 * 计数服务
 */

public class CounterService extends Service {
    //计数器名常量
    public static final String COUNTER = "counter";
    //动作名
    public static final String ACTION_NAME = "linchange.com.activityservice.COUNTER_ACTION";

    private static final int MAX_VALUE = 100; //最大值

    public int count; //计数变量

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        //从intent中获取点击次数
        count = intent.getIntExtra(COUNTER, 1000);

        final Intent countIntent = new Intent(); //计数意图
        countIntent.setAction(ACTION_NAME); //设置意图的动作

        new Thread() {
            @Override
            public void run() {
                try {
                    while (count < MAX_VALUE) { //当前次数小于最大次数
                        count++; //次数加一
                        countIntent.putExtra(COUNTER, count); //设置数据
                        sendBroadcast(countIntent); //发送广播
                        Thread.sleep(200);
                    }
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }.start();

        return START_STICKY; //服务被关闭后会再启动，若是没有新的intent，则参数为null
    }
}

最后记得在AndroidManifest.xml对Service进行注册：

<application>
  <service android:name=".CounterService" />
</application>