Android 四大组件之 Service

package com.newcj.test;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;

public class LocalService1 extends Service {
    /**
     * onBind 是 Service 的虚方法，因此我们不得不实现它。 返回 null，表示客服端不能建立到此服务的连接。
     */
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();
    }

    @Override
    public void onStart(Intent intent, int startId) {
        super.onStart(intent, startId);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
    }
}

package com.newcj.test;

import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;

public class LocalService extends Service {
    /**
     * 在 Local Service 中我们直接继承 Binder 而不是 IBinder,因为 Binder 实现了 IBinder
     * 接口，这样我们可以少做很多工作。
     * 
     * @author newcj
     */
    public class SimpleBinder extends Binder {
        /**
         * 获取 Service 实例
         * 
         * @return
         */
        public LocalService getService() {
            return LocalService.this;
        }

        public int add(int a, int b) {
            return a + b;
        }
    }

    public SimpleBinder sBinder;

    @Override
    public void onCreate() {
        super.onCreate();
        // 创建 SimpleBinder
        sBinder = new SimpleBinder();
    }

    @Override
    public IBinder onBind(Intent intent) {
        // 返回 SimpleBinder 对象
        return sBinder;
    }
}

package com.newcj.test;

import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
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;

public class Main extends Activity {
    private final static String TAG = "SERVICE_TEST";
    private ServiceConnection sc;
    private boolean isBind;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        sc = new ServiceConnection() {
            @Override
            public void onServiceDisconnected(ComponentName name) {
            }

            @Override
            public void onServiceConnected(ComponentName name, IBinder service) {
                LocalService.SimpleBinder sBinder = (LocalService.SimpleBinder) service;
                Log.v(TAG, "3 + 5 = " + sBinder.add(3, 5));
                Log.v(TAG, sBinder.getService().toString());
            }
        };
        findViewById(R.id.btnBind).setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                bindService(new Intent(Main.this, LocalService.class), sc,
                        Context.BIND_AUTO_CREATE);
                isBind = true;
            }
        });
        findViewById(R.id.btnUnbind).setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                if (isBind) {
                    unbindService(sc);
                    isBind = false;
                }
            }
        });
    }
}

package com.newcj.test;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.os.IBinder;

public class ForegroundService extends Service {
    private static final Class[] mStartForegroundSignature = new Class[] {
            int.class, Notification.class };
    private static final Class[] mStopForegroundSignature = new Class[] { boolean.class };
    private NotificationManager mNM;
    private Method mStartForeground;
    private Method mStopForeground;
    private Object[] mStartForegroundArgs = new Object[2];
    private Object[] mStopForegroundArgs = new Object[1];

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

    @Override
    public void onCreate() {
        super.onCreate();
        mNM = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        try {
            mStartForeground = ForegroundService.class.getMethod(
                    "startForeground", mStartForegroundSignature);
            mStopForeground = ForegroundService.class.getMethod(
                    "stopForeground", mStopForegroundSignature);
        } catch (NoSuchMethodException e) {
            mStartForeground = mStopForeground = null;
        }
        // 我们并不需要为 notification.flags 设置 FLAG_ONGOING_EVENT，因为
        // 前台服务的 notification.flags 总是默认包含了那个标志位
        Notification notification = new Notification(R.drawable.icon,
                "Foreground Service Started.", System.currentTimeMillis());
        PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                new Intent(this, Main.class), 0);
        notification.setLatestEventInfo(this, "Foreground Service",
                "Foreground Service Started.", contentIntent);
        // 注意使用 startForeground ，id 为 0 将不会显示 notification
        startForegroundCompat(1, notification);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        stopForegroundCompat(1);
    }

    // 以兼容性方式开始前台服务
    private void startForegroundCompat(int id, Notification n) {
        if (mStartForeground != null) {
            mStartForegroundArgs[0] = id;
            mStartForegroundArgs[1] = n;
            try {
                mStartForeground.invoke(this, mStartForegroundArgs);
            } catch (IllegalArgumentException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            } catch (InvocationTargetException e) {
                e.printStackTrace();
            }
            return;
        }
        setForeground(true);
        mNM.notify(id, n);
    }

    // 以兼容性方式停止前台服务
    private void stopForegroundCompat(int id) {
        if (mStopForeground != null) {
            mStopForegroundArgs[0] = Boolean.TRUE;
            try {
                mStopForeground.invoke(this, mStopForegroundArgs);
            } catch (IllegalArgumentException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            } catch (InvocationTargetException e) {
                e.printStackTrace();
            }
            return;
        }
        // 在 setForeground 之前调用 cancel，因为我们有可能在取消前台服务之后
        // 的那一瞬间被kill掉。这个时候 notification 便永远不会从通知一栏移除
        mNM.cancel(id);
        setForeground(false);
    }
}