springboot13 发布和监听事件

spring中的事件驱动模型Event（也叫发布订阅模式）,是观察者模式的一个典型的应用

好处：业务解耦，在不影响原来业务逻辑的情况下，加入其它业务

场景：

app上线后已实现用户注册功能，现需要在用户注册成功后给用户发送短信提示。

因为怕发送短信的代码逻辑发送异常会影响以前的用户注册功能，所以将发送短信功能设置成监听事件，在用户注册成功后发布一个事件，在事件监听器中监听到该事件后处理发送短信逻辑。如果发送短信发生异常，不会影响用户注册功能。

代码实现：

新建maven项目，引入依赖：

<!--父依赖包-->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.3.2.RELEASE</version>
        <relativePath/>
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

    </dependencies>

项目其他结构：

User

public class User {
    private int id;
    private String name;

    public User() {
    }

    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;
    }
}

UserService

import com.mlxs.springboot.event.bean.User;
import com.mlxs.springboot.event.event.UserRegisterEvent;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.stereotype.Service;

import java.util.ArrayList;
import java.util.List;

/**
 * UserService类描述:
 *
 * @author yangzhenlong
 * @since 2018/1/12
 */
@Service
public class UserService {
    @Autowired
    private ApplicationContext applicationContext;

    private List<User> userList = new ArrayList<>();

    public User register(User user) {
        userList.add(user);
        //发布事件
        applicationContext.publishEvent(new UserRegisterEvent(this, user));
        return user;
    }

    public List<User> getAll(){
        return userList;
    }
}

UserRest

@RestController
public class UserRest {
    @Autowired
    private UserService userService;

    @RequestMapping("/user/all")
    List<User> getAll(){
        return userService.getAll();
    }

    @RequestMapping("/user/register")
    User register(@RequestBody User user){
        return userService.register(user);
    }
}

StartApp

@SpringBootApplication
public class StartApp {
    public static void main(String[] args) {
        SpringApplication.run(StartApp.class, args);
    }
}

UserRegisterEvent 用户注册事件

public class UserRegisterEvent extends ApplicationEvent {
    private Object source;
    private User user;
    public UserRegisterEvent(Object source, User user) {
        super(source);
        this.user = user;
    }

    @Override
    public Object getSource() {
        return source;
    }

    public void setSource(Object source) {
        this.source = source;
    }

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }
}

UserRegisterEventListener 用户事件监听

@Component
public class UserRegisterEventListener {

    @EventListener
    public void register(UserRegisterEvent event){
        User user = event.getUser();
        System.out.println("-----------监听到用户注册事件------,给用户【" + user.getName() + "】发送短信...");
    }
}

启动项目，调用 register接口，注册2个用户：

{
    "id":1,
    "name":"hello"
}
------------------------------
{
    "id":2,
    "name":"刘德华"
}

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