BindService总结

一、整体工程图

二、activity_bind.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:orientation="vertical">

<Button android:text="useService"
    android:id="@+id/buttonUseService"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"></Button>
</LinearLayout>

三、BindActivity.java

package com.jltxgcy.bindservice;

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;
import android.widget.Toast;

import com.jltxgcy.bindservice.LocalService.LocalBinder;

public class BindActivity extends Activity {

	LocalService mService;
    boolean mBound = false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_bind);
        findViewById(R.id.buttonUseService).setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				if (mBound) {
		            // Call a method from the LocalService.
		            // However, if this call were something that might hang, then this request should
		            // occur in a separate thread to avoid slowing down the activity performance.
		            int num = mService.getRandomNumber();
		            Toast.makeText(BindActivity.this, "number: " + num, Toast.LENGTH_SHORT).show();
		        }

			}
		});
    }

    @Override
    protected void onStart() {
        super.onStart();
        // Bind to LocalService
        Intent intent = new Intent(this, LocalService.class);
        bindService(intent, mConnection, Context.BIND_AUTO_CREATE);
    }

    @Override
    protected void onStop() {
        super.onStop();
        // Unbind from the service
        if (mBound) {
            unbindService(mConnection);
            mBound = false;
        }
    }

    /** Defines callbacks for service binding, passed to bindService() */
    private ServiceConnection mConnection = new ServiceConnection() {

        @Override
        public void onServiceConnected(ComponentName className,
                IBinder service) {
            // We've bound to LocalService, cast the IBinder and get LocalService instance
            LocalBinder binder = (LocalBinder) service;
            mService = binder.getService();
            mBound = true;
            Log.d("jltxgcy", "onServiceConnected");
        }

        //Called when the connection with the service disconnects unexpectedly
        @Override
        public void onServiceDisconnected(ComponentName arg0) {
            mBound = false;
            Log.d("jltxgcy", "onServiceDisconnected");
        }
    };
}

四、LocalService.java

package com.jltxgcy.bindservice;

import java.util.Random;

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

public class LocalService extends Service {
	public static final String TAG="jltxgcy";
	 // Binder given to clients
    private final IBinder mBinder = new LocalBinder();
    // Random number generator
    private final Random mGenerator = new Random();

    @Override
	public void onCreate() {
    	Log.d(TAG, "onCreate");
		super.onCreate();
	}

	/**
     * Class used for the client Binder.  Because we know this service always
     * runs in the same process as its clients, we don't need to deal with IPC.
     */
    public class LocalBinder extends Binder {
        LocalService getService() {
            // Return this instance of LocalService so clients can call public methods
            return LocalService.this;
        }
    }

    @Override
    public IBinder onBind(Intent intent) {
    	Log.d(TAG, "onBind");
        return mBinder;
    }

    /** method for clients */
    public int getRandomNumber() {
      return mGenerator.nextInt(100);
    }

	@Override
	public boolean onUnbind(Intent intent) {
		Log.d(TAG, "onUnbind");
		return super.onUnbind(intent);
	}

	@Override
	public void onDestroy() {
		Log.d(TAG, "onDestroy");

	}
}

五、详解

程序开始，绑定Service，结果显示如下：

说明了调用的先后顺序。onBind方法得到了IBinder对象，onServiceConnected方法将IBinder对象向下转型为LocalBinder对象，通过调用getService取得Service实例， 这样就可以在BindActivity中使用Service的方法。

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