一、Service的简介
Service是Android中实现程序后台运行的解决方案，适用于去执行那些不需要和用户交互而且还要求长期运行的任务。Service是android 系统中的四大组件之一（Activity、Service、BroadcastReceiver、ContentProvider），它跟Activity的级别差不多，但不能自己运行只能后台运行，并且可以和其他组件进行交互。
Service的分类如下
作用：提供 需在后台长期运行的服务
特点：无用户界面、在后台运行、生命周期长
1、Service的生命周期 官方说明图
启动服务
生命周期为：onCreate->onStartCommand->onDestory
1.startService开启服务时，生命周期为
执行onCreate->onStartCommand(Android2.0之后用的都是这个,Android2.0以前是onStart)
一旦启动，服务可以在后台无限期运行，即使启动它的组件已经被销毁。
For example:音乐播放器，退出APP后，依然可以听歌，这是服务在后台运行的作用，否则无法播放音乐。
stopService关闭服务时，执行onDestory
绑定服务
生命周期为：onCreate->onBind->onUnBind->onDestory
2.bindService 绑定服务时，执行onCreate->onBind
unbindSerivce解绑服务时，执行onUnBind->onDestory
1、首先创建MyService类继承Service
/**
* 自定义本地服务
*/
/*
1.startService()
第一次调用：-->构造方法()-->onCreate()-->onStartCommand()
后面再调用：-->onStartCommand()
stopService():-->onDestroy()
2.bindService(Intent service, ServiceConnection conn,int flags)
第一次调用：-->构造方法()-->onCreate()-->onBind()-->onServiceConnected()
unbindService(connection):-(只有当前Activity与Service连接)->onUnbind()-->onDestroy()
*/
public class MyService extends Service {
public MyService() {
Log.i("TAG", "MyService() ");
}
@Override
public void onCreate() {
super.onCreate();
Log.i("TAG", "MyService onCreate() ");
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.i("TAG", "MyService onStartCommand() ");
return super.onStartCommand(intent, flags, startId);
}
@Override
public void onDestroy() {
super.onDestroy();
Log.i("TAG", "MyService onDestroy() ");
}
@Nullable
@Override
public IBinder onBind(Intent intent) {
Log.i("TAG", "onBind() ");
return new Binder();
}
@Override
public boolean onUnbind(Intent intent) {
Log.i("TAG", "onUnbind() ");
return super.onUnbind(intent);
}
}
2、在AndroidManifest.xml中进行注册
<service android:name=".local.MyService" />
3、ServiceActivity代码如下
public class ServiceActivity extends AppCompatActivity {
private ServiceConnection connection;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_service);
}
//启动服务
public void startMyService(View view) {
Intent intent = new Intent(this, MyService.class);
startService(intent);
Toast.makeText(this, "启动服务！", Toast.LENGTH_SHORT).show();
}
public void stopMyService(View view) {
Intent intent = new Intent(this, MyService.class);
stopService(intent);
Toast.makeText(this, "停止服务！", Toast.LENGTH_SHORT).show();
}
//绑定服务
public void bindMyService(View view) {
Intent intent = new Intent(this, MyService.class);
//创建连接对象
if (connection == null) {
connection = new ServiceConnection() {
//当与服务连接上之后，回调该方法
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
Log.i("TAG", "onServiceConnected()");
}
//这个方法始终不会执行，不用管它
@Override
public void onServiceDisconnected(ComponentName name) {
Log.i("TAG", "onServiceDisconnected()");
}
};
//绑定service
//BIND_AUTO_CREATE表示：创建之后自动绑定
bindService(intent, connection, BIND_AUTO_CREATE);
Toast.makeText(this, "绑定服务！", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(this, "已经绑定服务！", Toast.LENGTH_SHORT).show();
}
}
//解绑服务
public void unBindMyService(View view) {
if (connection != null) {
unbindService(connection);
connection = null;
Toast.makeText(this, "解绑服务！", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(this, "还未进行绑定服务！", Toast.LENGTH_SHORT).show();
}
}
//当绑定服务后，不解绑服务直接退出，会有错误抛出，所以需要在
//当前Activity页面销毁的时候，执行解绑服务
@Override
protected void onDestroy() {
super.onDestroy();
if (connection != null) {
unbindService(connection);
connection = null;
}
}
}二、远程服务AIDL的讲解
AIDL的理解
具体需求如下
具体步骤如下，首先写服务端应用
1、创建远程服务类MyRemoteService继承Service类
/**
* 远程服务
*/
public class MyRemoteService extends Service {
@Nullable
@Override
public IBinder onBind(Intent intent) {
Log.i("TAG", "onBind() ");
return new StudentService();
}
@Override
public boolean onUnbind(Intent intent) {
Log.i("TAG", "onUnbind() ");
return super.onUnbind(intent);
}
//处理Student相关的业务逻辑类
class StudentService extends IStudentService.Stub {
@Override
public Student getStudentById(int id) throws RemoteException {
Log.i("TAG", "Service getStudentById() " + id);
return new Student(id, "Tom", 10000);
}
}
}
2、在AndroidManifest.xml文件中注册该服务
<service android:name=".local.MyRemoteService">
<intent-filter>
<action android:name="local.MyRemoteService.Action" />
</intent-filter>
</service>
3、创建Student类，并实现Parcelable接口,传递对象
public class Student implements Parcelable {
private int id;
private String name;
private double price;
public Student(int id, String name, double price) {
this.id = id;
this.name = name;
this.price = price;
}
protected Student(Parcel in) {
id = in.readInt();
name = in.readString();
price = in.readDouble();
}
public static final Creator<Student> CREATOR = new Creator<Student>() {
@Override
public Student createFromParcel(Parcel in) {
Log.i("TAG", "解包createFromParcel()");
return new Student(in);
}
//返回一个指定大小的对象容器
@Override
public Student[] newArray(int size) {
return new Student[size];
}
};
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
@Override
public String toString() {
return "Student{" +
"id=" + id +
", name='" + name + '\'' +
", price=" + price +
'}';
}
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel dest, int flags) {
Log.i("TAG", "打包 writeToParcel() ");
dest.writeInt(id);
dest.writeString(name);
dest.writeDouble(price);
}
}4、在src的main目录下，创建aidl文件默认会生成aidl文件夹。创建两个aidl文件，分别为
IStudentService.aidl
package com.example.customviewproject.entity;
import com.example.customviewproject.entity.Student;
interface IStudentService {
Student getStudentById(int id);
}
Student.aidl
// Student.aidl
package com.example.customviewproject.entity;
// Declare any non-default types here with import statements
parcelable Student;
AIDL的一些规则如下
服务端创建好后，客户端将服务端的aidl文件和Student类，原封不动的拷贝到客户端应用，意思就是说路径不要变。
客户端的界面如下
MainActivity中进行具体代码的编写，代码如下
public class MainActivity extends AppCompatActivity {
private EditText edit_id;
private ServiceConnection connection;
private IStudentService iStudentService;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
edit_id = findViewById(R.id.edit_id);
}
//绑定远端服务
public void bindRemoteService(View view) {
Intent intent = new Intent("local.MyRemoteService.Action");
intent.setPackage("com.example.customviewproject");
if (connection == null) {
connection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
Log.i("TAG", "onServiceConnected() ");
iStudentService = IStudentService.Stub.asInterface(iBinder);
}
@Override
public void onServiceDisconnected(ComponentName componentName) {
}
};
bindService(intent, connection, BIND_AUTO_CREATE);
} else {
Toast.makeText(this, "已经绑定远端服务！", Toast.LENGTH_SHORT).show();
}
}
//调用远程服务端的方法
public void callRemoteMethod(View view) {
if (iStudentService != null) {
int id = Integer.parseInt(edit_id.getText().toString());
try {
Student student = iStudentService.getStudentById(id);
Log.i("TAG", "callRemoteMethod() student.toString():" + student.toString());
} catch (RemoteException e) {
e.printStackTrace();
}
}
}
//解绑远端服务
public void UnbindService(View view) {
if (connection != null) {
unbindService(connection);
connection = null;
iStudentService = null;
Toast.makeText(this, "解绑远端服务！", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(this, "还未绑定远端服务！", Toast.LENGTH_SHORT).show();
}
}
}当用户首次进入后，点击绑定远端服务按钮执行的流程依次为
点击调用远程服务端的按钮，执行的流程依次为
点击解绑远程服务按钮，执行的流程依次为
以上是Service讲解，有什么不当之处，可在评论区指正共同学习!