开发►Spring

Spring常见问题

如何配置定时任务

Spring 3中涉及定时任务的主要是TaskScheduler接口，利用spring的task命名空间，可以很简单地配置一个定时任务，以下是配置一个简单的定时任务（每隔5秒执行一次beanA.methodA方法）

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<beans xmlns:task="http://www.springframework.org/schema/task"
  ......>
    <task:scheduler id="myScheduler" pool-size="10"/>
    <task:scheduled-tasks scheduler="myScheduler">
        <task:scheduled ref="beanA" method="methodA" fixed-rate="5000"/>
    </task:scheduled-tasks>
    ......
</beans>

如何使用spring4.x配置RESTFUL API

pom.xml

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<dependencies>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>4.3.2.RELEASE</version>
    </dependency>
    <!--
        jackson 2的包在classpath时，spring会使用该包进行json转换，详见spring官方文档的
        “Enabling the MVC Java Config or the MVC XML Namespace”
     -->
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.8.3</version>
    </dependency>
</dependencies>

一个简单的Controller

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@RestController
@RequestMapping("/users")
public class RestfulController {
    /**
     * 方式1
     *
     * @param id
     * @return 返回一个ResponseEntity对象
     */
    @RequestMapping(value="/type1/{id}", method = RequestMethod.GET)
    public ResponseEntity<User> getUserById1(@PathVariable int id) {
        return ResponseEntity.ok(new User(id, "type1 user"));
    }
    /**
     * 方式2
     *
     * @param id
     * @return 返回一个POJO
     */
    @RequestMapping(value="/type2/{id}", method = RequestMethod.GET)
    public User getUserById2(@PathVariable String id) {
        return new User(1, "type2 user");
    }
}

POJO对象

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public class User {
    private final int id;
    private final String name;
    public User(int id, String name) {
        this.id = id;
        this.name = name;
    }
    public int getId() {
        return id;
    }
    public String getName() {
        return name;
    }
}

web.xml

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<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
                      http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
         version="3.0"
         metadata-complete="true">
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring-mvc.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>
</web-app>

spring-mvc.xml

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<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd">
    <context:component-scan base-package="io.jasonlu.springrestful.controller"/>
    <mvc:annotation-driven/>
</beans>