Android中的Service基础

Service主要用于后台程序和跨进程访问，可以在不显示界面的前提下完成任务，不影响用户的其他操作。

这里我展示一些基本的用法

新建一个Service类

package com.example.service;

import android.app.Service;

import android.content.Intent;

import android.os.Binder;

import android.os.IBinder;

import android.widget.Toast;

public class MyService extends Service {

    private IBinder myBinder=new Binder(){

        public String getInterfaceDescriptor(){

            return "MyServerceUtil class.";

        }

    };

    public IBinder onBind(Intent intent)//绑定时触发

    {

        Toast.makeText(getApplicationContext(),"服务绑定",Toast.LENGTH_SHORT).show();

        return myBinder;

    }

    public void onRebind(Intent intent)//重新绑定时触发

    {

        super.onRebind(intent);

    }

    public boolean onUnbind(Intent intent)//解除绑定时触发

    {Toast.makeText(getApplicationContext(),"服务解绑",Toast.LENGTH_SHORT).show();

        return super.onUnbind(intent);

    }

    public void onCreate(){

        super.onCreate();

    }//创建时触发

    public void onDestroy(){

        super.onDestroy();

        Toast.makeText(getApplicationContext(),"服务销毁",Toast.LENGTH_SHORT).show();

    }

    public int onStartCommand(Intent intent,int flags,int startId)//启动时触发

    {

        Toast.makeText(getApplicationContext(),"服务启动",Toast.LENGTH_SHORT).show();

        return  Service.START_NOT_STICKY;

    }

}

　　在Mainactivity中调用

package com.example.service;

import androidx.appcompat.app.AppCompatActivity;

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.view.View;

import android.widget.Button;

public class MainActivity extends AppCompatActivity {

private Button start=null;

private Button bind=null;

private Button stop=null;

private Button unbind=null;

private ServiceConnection serviceConnection =new ServiceConnection() {

        @Override

        //连接

        public void onServiceConnected(ComponentName name, IBinder service) {

        }

        @Override

        //断开连接

        public void onServiceDisconnected(ComponentName name) {

        }

    };

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        start=(Button)super.findViewById(R.id.start);

        stop=(Button)super.findViewById(R.id.stop);

        bind=(Button)super.findViewById(R.id.bind);

        unbind=(Button)super.findViewById(R.id.unbind);

        start.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                MainActivity.this.startService(new Intent(MainActivity.this,MyService.class));

            }

        });

        stop.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                MainActivity.this.stopService(new Intent(MainActivity.this,MyService.class));

            }

        });

    bind.setOnClickListener(new View.OnClickListener() {

    @Override

     public void onClick(View v) {

        //绑定

    MainActivity.this.bindService(new Intent(MainActivity.this,MyService.class),

            MainActivity.this.serviceConnection, Context.BIND_AUTO_CREATE);

    }

});

    unbind.setOnClickListener(new View.OnClickListener() {

        @Override

        public void onClick(View v) {

            //解除绑定

            MainActivity.this.unbindService(MainActivity.this.serviceConnection);

        }

    });

    }

}

　　

服务的onCreate（）函数在服务第一次启动时会执行一次，之后若不销毁的话再次启动就不会执行，只执行onStartCommand

绑定的用途是把Activity与Service绑定在一起，绑定后当Activity停止时，Service也会停止；未绑定时Activity退出后，Service会仍然运行。