service---startService 和bindService

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本文围绕Android的Service展开，介绍其主要用于在后台处理耗时操作，阐述了startService和bindService两种方式下的生命周期，还提到Service可开辟线程、访问网络和操作数据库，以及创建继承Service的类，在activity中使用startService、stopService、bindService等方法的使用要点。

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https://developer.android.com/reference/android/app/Service

service的主要作用

用于在后台处理耗时操作

service的生命周期

1 callTo startService---onCreate----onStartCommand-----serviceRuning ----onStart----onDestory startService

2 callTobindService---onCreate---onBind----Clients are bound to service----onUnbind----onDestory bindService

Service 可以开辟线程

访问网络炒作数据库(一个没有页面的activity)

创建一个class继承service

startService

package com.androidless1.yifei.andrlidl1;

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

public class ServiceActivity extends Service {

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

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.d(MainActivity.TAG, "Service onStart: ");
        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    public void onDestroy() {
        Log.d(MainActivity.TAG, "Service onDestroy: ");
        super.onDestroy();
    }

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

activity中使用startService调用service 和stopService停止service

package com.androidless1.yifei.andrlidl1;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    public static final String TAG = "MainActivity" + 123;
    private Button btn1;
    private Button btn2;
    Intent intent;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn1 = findViewById(R.id.btn1);
        btn1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                 intent = new Intent(MainActivity.this,ServiceActivity.class);
                startService(intent);
            }
        });
        btn2 = findViewById(R.id.btn2);
        btn2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
            stopService(intent);
            }
        });
    }
}

bindService

创建一个类继承Service

package com.androidless1.yifei.andrlidl1;

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

public class BindService extends Service {
    @Override
    public void onCreate() {
        Log.d(MainActivity.TAG, "onCreate: ");
        super.onCreate();
    }

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

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.d(MainActivity.TAG, "onStartCommand: ");
        return super.onStartCommand(intent, flags, startId);
    }

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

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

bindService(intent,ServiceConnection,BIND_AUTO_CREATE)

package com.androidless1.yifei.andrlidl1;

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.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    public static final String TAG = "MainActivity" + 123;
    private Button btn1;
    private Button btn2;
    private Button btn3;
    private Button btn4;
    Intent intent;
    Intent intentBind;

    public ServiceConnection mConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            Log.d(TAG, "onServiceConnected: ");
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            Log.d(TAG, "onServiceDisconnected: ");
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn3 = findViewById(R.id.btn3);
        btn4 = findViewById(R.id.btn4);
        btn3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                intentBind = new Intent(MainActivity.this, BindService.class);
                bindService(intentBind,mConnection,BIND_AUTO_CREATE);
            }
        });
        btn4.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                unbindService(mConnection);
            }
        });
    }
}

如果没有bind而直接unBind会报错

bind和Unbind改为

package com.androidless1.yifei.andrlidl1;

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.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    public static final String TAG = "MainActivity" + 123;
    private Button btn1;
    private Button btn2;
    private Button btn3;
    private Button btn4;
    private Boolean isBind =false;
    Intent intent;
    Intent intentBind;

    public ServiceConnection mConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            Log.d(TAG, "onServiceConnected: ");
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            Log.d(TAG, "onServiceDisconnected: ");
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn1 = findViewById(R.id.btn1);
        btn1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                intent = new Intent(MainActivity.this, ServiceActivity.class);
                startService(intent);
            }
        });
        btn2 = findViewById(R.id.btn2);
        btn2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                stopService(intent);
            }
        });
        btn3 = findViewById(R.id.btn3);
        btn4 = findViewById(R.id.btn4);
        btn3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                intentBind = new Intent(MainActivity.this, BindService.class);
                if(bindService(intentBind,mConnection,BIND_AUTO_CREATE)){
                    isBind =true;
                };
            }
        });
        btn4.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(isBind){
                    unbindService(mConnection);
                    isBind=false;
                }

            }
        });
    }
}