Service的肤浅了解

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Service就我自己理解就是当你退出程序之后，程序还可以在后台运行的控件
最简单的实现Service方法就是创建一个类继承Service

发现它跟Activity有点类似因为Service也有oncreate
onstart ondestory的方法（其他的就没有了）
打开源代码 Service竟然有这么多方法这里写图片描述

额但是现在用一些最常用的方法 onBind onUnbind
onStartCommand 这些常用的方法

了解一个控件就需要了解这些方法在什么时候执行（我指的是我自己常用的那些）

就我现在所知启动Service有两种方法bindService和StartService

于是就设置4个按钮

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    tools:context=".MainActivity">    <TextView        android:id="@+id/textshow"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="show me "/>    <Button        android:id="@+id/startservice"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:text="startService"        />    <Button        android:id="@+id/stopservice"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:text="stopService"        />    <Button        android:id="@+id/bindservice"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:text="bindService"        />    <Button        android:id="@+id/unbindservice"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:text="unbindService"        /></LinearLayout>

MainActivity

package com.example.administrator.calculator;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.widget.Button;import android.widget.TextView;public class MainActivity extends Activity implements View.OnClickListener{//    当我们想获取启动的Service实例时，我们可以用到bindService和onBindService方法，它们分别执行了Service中IBinder()和onUnbind()方法。    private Button startService,stopService,bindService,unbindService;    private TestService testService;    private TextView tv;    private Context mcontext;    //这里需要用到ServiceConnection在Context.bindService和context.unBindService()里用到    private ServiceConnection mServiceConnection = new ServiceConnection() {        //当我bindService时，让TextView显示MyService里getSystemTime()方法的返回值        @Override        public void onServiceConnected(ComponentName name, IBinder service) {            Log.e("MYSERVICEmAIN","onServiceConnected");            testService = ((TestService.MyBinder)service).getService();            tv.setText("I am from Service :" + testService.getString());        }        @Override        public void onServiceDisconnected(ComponentName name) {            Log.e("MYSERVICEmAIN","onServiceDisconnected");        }    };    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        setupView();    }    private void setupView() {        mcontext = MainActivity.this;        tv = (TextView) findViewById(R.id.textshow);        startService = (Button) findViewById(R.id.startservice);        stopService = (Button) findViewById(R.id.stopservice);        bindService = (Button) findViewById(R.id.bindservice);        unbindService = (Button) findViewById(R.id.unbindservice);        startService.setOnClickListener(this);        stopService.setOnClickListener(this);        bindService.setOnClickListener(this);        unbindService.setOnClickListener(this);;    }    @Override    public void onClick(View v) {        Intent i;        if(v==startService){            i = new Intent(MainActivity.this,TestService.class);            mcontext.startService(i);        }else if(v==stopService){            i = new Intent(MainActivity.this,TestService.class);            mcontext.stopService(i);        }else if(v==bindService){            i = new Intent(MainActivity.this,TestService.class);            mcontext.startService(i);            mcontext.bindService(i,mServiceConnection,BIND_AUTO_CREATE);        }else{            mcontext.unbindService(mServiceConnection);        }    }}

TestService.java

package com.example.administrator.calculator;import android.app.Service;import android.content.Intent;import android.os.Binder;import android.os.IBinder;import android.support.annotation.Nullable;import android.text.format.Time;import android.util.Log;/** * Created by Administrator on 2015/11/21. */public class TestService extends Service{//   定义一个Tag标签    private static final String TAG = "MYSERVICE";//    这里定义一个Binder 用在onBind()方法，这样Activity那边好、可以获取到    private  MyBinder myBinder = new MyBinder();    @Nullable    @Override    public IBinder onBind(Intent intent) {        Log.e(TAG,"onBind");        return myBinder;    }    @Override    public void onCreate() {        Log.e(TAG,"onCreate");        super.onCreate();    }    @Override    public void onStart(Intent intent, int startId) {        Log.e(TAG,"onStart");        super.onStart(intent, startId);    }    @Override    public void onDestroy() {        Log.e(TAG,"onDestroy");        super.onDestroy();    }    @Override    public boolean onUnbind(Intent intent) {        Log.e(TAG,"onUnbind");        return super.onUnbind(intent);    }    public String getString(){        return "获取到Service实例";    }    public class MyBinder extends Binder{        TestService getService(){            return TestService.this;        }    }    @Override    public int onStartCommand(Intent intent, int flags, int startId) {        Log.e(TAG,"onStartCommand");        return super.onStartCommand(intent, flags, startId);    }}

按顺序按按钮
这里写图片描述

结果

这里写图片描述

今天就到此为止

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