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Spring MVC 實現RESTful 返回JSON格式資料

在Java後端的日常開發中,系統間呼叫通過使用json格式資料,本文將向你展示如何將物件轉換成json格式並通過Spring MVC框架返回給呼叫者。

開發工具配置

  • Spring 4.2.7.RELEASE
  • Jackson 2.6.7
  • JDK 1.7
  • IntelliJ IDEA 15
  • Maven 3.3.9

1、maven依賴

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation
="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion> <groupId>com.ricky.codelab</groupId> <artifactId>springmvc</artifactId> <packaging>war</packaging> <version>1.0-SNAPSHOT</version
>
<name>Spring MVC 4.x Demo</name> <url>http://maven.apache.org</url> <properties> <spring.version>4.2.7.RELEASE</spring.version> <jackson.version>2.6.7</jackson.version> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding
>
</properties> <dependencies> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context-support</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-aop</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-beans</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-tx</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-jdbc</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <version>${jackson.version}</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <version>${jackson.version}</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>${jackson.version}</version> </dependency> <dependency> <groupId>jstl</groupId> <artifactId>jstl</artifactId> <version>1.2</version> </dependency> <dependency> <groupId>taglibs</groupId> <artifactId>standard</artifactId> <version>1.1.2</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>3.1.0</version> <scope>compile</scope> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> <scope>test</scope> </dependency> </dependencies> <profiles> <profile> <id>beta</id> <build> <resources> <resource> <directory>src/main/resources</directory> </resource> <resource> <directory>src/main/resources_beta</directory> </resource> </resources> </build> <!-- 把當前profile設定為預設profile,可以同時這是多個為預設--> <activation> <activeByDefault>true</activeByDefault> </activation> </profile> <profile> <id>online</id> <build> <resources> <resource> <directory>src/main/resources</directory> </resource> <resource> <directory>src/main/resources_online</directory> </resource> </resources> </build> </profile> </profiles> <build> <finalName>springmvc</finalName> </build> </project>

2、Spring配置檔案

applicationContext.xml

<?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:jee="http://www.springframework.org/schema/jee" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:task="http://www.springframework.org/schema/task" xmlns:util="http://www.springframework.org/schema/util" xmlns:jaxws="http://cxf.apache.org/jaxws"
       xsi:schemaLocation="
       http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/util
       http://www.springframework.org/schema/util/spring-util.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd"
       default-lazy-init="false">

    <util:properties id="db" location="classpath:mysql.properties"/>

    <context:component-scan base-package="com.ricky.codelab" />

    <context:annotation-config />
    <import resource="spring-mvc.xml"/>
</beans>

spring-mvc.xml

<?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-4.1.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.1.xsd">

    <context:component-scan base-package="com.ricky.codelab.springmvc.controller"></context:component-scan>

    <mvc:annotation-driven/>

    <bean id="viewResolver" class="org.springframework.web.servlet.view.UrlBasedViewResolver">
        <property name="viewClass"
                  value="org.springframework.web.servlet.view.JstlView" />
        <property name="prefix" value="/WEB-INF/pages/" />
        <property name="suffix" value=".jsp" />
    </bean>
</beans>

3、web.xml

<!DOCTYPE web-app PUBLIC
        "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
        "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
    <display-name>Spring MVC 4.2 Demo</display-name>

    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>
            classpath*:/applicationContext*.xml;
        </param-value>
    </context-param>

    <filter>
        <filter-name>characterEncodingFilter</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
        <init-param>
            <param-name>forceEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>characterEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <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>

    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>
</web-app>

4、Model

package com.ricky.codelab.springmvc.domain;

/**
 * ${DESCRIPTION}
 *
 * @author Ricky Fung
 * @create 2016-07-12 16:54
 */
public class User {
    private String username;
    private String password;
    private String email;
    private int age;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

}

5、Controller

在需要返回json格式資料的Controller method上新增@ResponseBody註解,如下:

package com.ricky.codelab.springmvc.controller;

import com.ricky.codelab.springmvc.domain.User;
import com.ricky.codelab.springmvc.service.IUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;

/**
 * Spring MVC RESTful JSON
 *
 * @author Ricky Fung
 * @create 2016-07-13 11:41
 */
@Controller
@RequestMapping("/user")
public class RESTfulJSONController {

    @Autowired
    private IUserService userService;

    /**Spring MVC RESTful JSON**/
    @RequestMapping(value = "/view/{username}", method = RequestMethod.GET)
    @ResponseBody
    public User view(@PathVariable String username){

        System.out.println("view username:"+username);

        return userService.findUserByName(username);
    }

    @RequestMapping(value = "/query", method = RequestMethod.GET)
    @ResponseBody
    public User query(@RequestParam(value="username", required=true) String username){

        System.out.println("view username:"+username);

        return userService.findUserByName(username);
    }

}

Spring MVC框架會自動幫我們將Object 轉換為JSON string。

6、驗證結果

返回結果:

{
username: “ricky “,
password: “123”,
email: “ricky @163.com”,
age: 27
}