Spring RESTful服务接收和返回JSON最佳实践

返回JSON

1) 用Maven构建web项目：

构建过程参考limingnihao的blog（写得相当的详细！！！）：使用Eclipse构建Maven的SpringMVC项目

注解@ResponseBody可以将结果（一个包含字符串和JavaBean的Map），转换成JSON。由于Spring是采用对JSON进行了封装的jackson来生成JSON和返回给客户端,所以这里需要添加jackson的相关包。项目的pom.xml配置如下：

<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.watson</groupId>
    <artifactId>rest-spring</artifactId>
    <packaging>war</packaging>
    <version>0.0.1-SNAPSHOT</version>
    <name>rest-spring Maven Webapp</name>
    <url>http://maven.apache.org</url>

    <dependencies>
        <!-- 省略其他配置,具体可以参考附件-->
        ......
        <dependency>
            <groupId>org.codehaus.jackson</groupId>
            <artifactId>jackson-mapper-asl</artifactId>
            <version>1.4.2</version>
        </dependency>
        <dependency>
            <groupId>org.codehaus.jackson</groupId>
            <artifactId>jackson-core-asl</artifactId>
            <version>1.4.2</version>
        </dependency>
    </dependencies>
</project>

  

2) 在web.xml配置Spring的请求处理的Servlet，具体设置：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    version="2.5">

    <display-name>Spring-Rest</display-name>
    <servlet>
        <servlet-name>rest</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/rest-servlet.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>rest</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

 

3) 在rest-servlet.xml中配置如下：

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">

    <context:component-scan base-package="com.mkyong.common.controller" />
    <mvc:annotation-driven />

</beans>

 

   为了解决乱码问题，需要添加如下配置，并且这里可以显示的添加MappingJacksonHttpMessageConverter这个转换器。

<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
    <property name="messageConverters">
        <list>
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <property name="supportedMediaTypes">
                    <list>
                        <value>text/plain;charset=UTF-8</value>
                    </list>
                </property>
            </bean>
            <bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter" />
        </list>
    </property>
</bean>

 

 

4) 编写自己的服务组件类，使用MVC的annotation风格，使用 @ResponseBody处理返回值。具体代码如下：

@RequestMapping("/jsonfeed")
public @ResponseBody Object getJSON(Model model) {
    List<TournamentContent> tournamentList = new ArrayList<TournamentContent>();
    tournamentList.add(TournamentContent.generateContent("FIFA", new Date(), "World Cup", "www.fifa.com/worldcup/"));
    tournamentList.add(TournamentContent.generateContent("FIFA", new Date(), "U-20 World Cup", "www.fifa.com/u20worldcup/"));
    tournamentList.add(TournamentContent.generateContent("FIFA", new Date(), "U-17 World Cup", "www.fifa.com/u17worldcup/"));
    tournamentList.add(TournamentContent.generateContent("中超", new Date(), "中超", "www.fifa.com/confederationscup/"));
    model.addAttribute("items", tournamentList);
    model.addAttribute("status", 0);

    return model;
}

 

 5)将运行项目，在浏览器中输入http://[host]:[port]/[appname]/jsonfeed.json，例如楼主的实例中输入如下：http://localhost:7070/rest-spring/jsonfeed/，得到结果为：

{"status":0,"items":[{"name":"World Cup","id":8,"link":"www.fifa.com/worldcup/","author":"FIFA","publicationDate":1334559460940},{"name":"U-20 World Cup","id":9,"link":"www.fifa.com/u20worldcup/","author":"FIFA","publicationDate":1334559460940},{"name":"U-17 World Cup","id":10,"link":"www.fifa.com/u17worldcup/","author":"FIFA","publicationDate":1334559460940},{"name":"Confederations Cup","id":11,"link":"www.fifa.com/confederationscup/","author":"FIFA","publicationDate":1334559460940}]}

 

这里我们也可以利用Spring3MVC中对试图和内容协商的方法来处理返回JSON的情况，下面步骤接上面第2步：

3) 在rest-servlet.xml中对相关进行具体的设置：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:aop="http://www.springframework.org/schema/aop" xmlns:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx-3.0.xsd">

    <!-- 自动搜索@Controller标注的类，包括其下面的子包 -->
    <context:component-scan base-package="com.watson.rest" />

    <!-- 根据客户端的不同的请求决定不同的view进行响应, 如 /blog/1.json /blog/1.xml -->
    <bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
        <!-- 设置为true以忽略对Accept Header的支持 -->
        <property name="ignoreAcceptHeader" value="true" />

        <!-- 在没有扩展名时即: "/blog/1" 时的默认展现形式 -->
        <property name="defaultContentType" value="text/html" />

        <!-- 扩展名至mimeType的映射,即 /blog.json => application/json -->
        <property name="mediaTypes">
            <map>
                <entry key="html" value="text/html" />
                <entry key="pdf" value="application/pdf" />
                <entry key="xsl" value="application/vnd.ms-excel" />
                <entry key="xml" value="application/xml" />
                <entry key="json" value="application/json" />
            </map>
        </property>

        <!-- 用于开启 /blog/123?format=json 的支持 -->
        <property name="favorParameter" value="false" />
        <property name="viewResolvers">
            <list>
                <bean class="org.springframework.web.servlet.view.BeanNameViewResolver" />
                <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
                    <property name="viewClass" value="org.springframework.web.servlet.view.JstlView" />
                    <property name="prefix" value="/pages" />
                    <property name="suffix" value=".jsp"></property>
                </bean>
            </list>
        </property>
        <property name="defaultViews">
            <list>
                <!-- for application/json -->
                <bean class="org.springframework.web.servlet.view.json.MappingJacksonJsonView" />
                <!-- for application/xml -->
                <!--
                <bean class="org.springframework.web.servlet.view.xml.MarshallingView">
                    <property name="marshaller">
                        <bean class="org.springframework.oxm.xstream.XStreamMarshaller"/>
                    </property>
                </bean>
                -->
            </list>
        </property>
    </bean>
</beans>

 

 4)编写自己的服务组件类，使用MVC的annotation风格，这里可以不再使用@ResponseBody断言。具体代码如下：

//FINAL
package com.watson.rest.json;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

import com.watson.rest.feeds.TournamentContent;

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


@Controller
public class FeedController {
    @RequestMapping("/jsonfeed")
    public String getJSON(Model model) {
        List<TournamentContent> tournamentList = new ArrayList<TournamentContent>();
        tournamentList.add(TournamentContent.generateContent("FIFA", new Date(), "World Cup", "www.fifa.com/worldcup/"));
        tournamentList.add(TournamentContent.generateContent("FIFA", new Date(), "U-20 World Cup", "www.fifa.com/u20worldcup/"));
        tournamentList.add(TournamentContent.generateContent("FIFA", new Date(), "U-17 World Cup", "www.fifa.com/u17worldcup/"));
        tournamentList.add(TournamentContent.generateContent("FIFA", new Date(), "Confederations Cup", "www.fifa.com/confederationscup/"));
        model.addAttribute("items", tournamentList);
        model.addAttribute("status", 0);
        return "jsontournamenttemplate";
    }
}

 

这里的TournamentContent是自定义的POJO类：

public class TournamentContent {
    private static int idCounter = 0;
    private String author;
    private Date publicationDate;
    private String name;
    private String link;
    private int id;

    public static TournamentContent generateContent(String author, Date date, String name, String link) {
        TournamentContent content = new TournamentContent();
        content.author = author;
        content.publicationDate = date;
        content.name = name;
        content.link = link;
        content.id = idCounter++;

        return content;
    }

    //省略getter、setter
}

 

5)将运行项目，在浏览器中输入http://[host]:[port]/[appname]/jsonfeed.json，例如楼主的实例中输入如下：http://localhost:7070/rest-spring/jsonfeed.json，得到结果为：

{"status":0,"items":[{"name":"World Cup","id":8,"link":"www.fifa.com/worldcup/","author":"FIFA","publicationDate":1334559460940},{"name":"U-20 World Cup","id":9,"link":"www.fifa.com/u20worldcup/","author":"FIFA","publicationDate":1334559460940},{"name":"U-17 World Cup","id":10,"link":"www.fifa.com/u17worldcup/","author":"FIFA","publicationDate":1334559460940},{"name":"Confederations Cup","id":11,"link":"www.fifa.com/confederationscup/","author":"FIFA","publicationDate":1334559460940}]}

 

至此，Spring RESTful服务返回JSON的实践基本完成（因为这里对EXCEPTION的处理还够）。个人认为第一种方式更加适合一般的使用，特别是显示的添加MappingJacksonHttpMessageConverter这个转换器和对乱码的处理。

 

接收JSON

使用 @RequestBody 注解前台只需要向 Controller 提交一段符合格式的 JSON，Spring 会自动将其拼装成 bean。

1)在上面的项目中使用第一种方式处理返回JSON的基础上，增加如下方法：

@RequestMapping(value="/add",method=RequestMethod.POST)
@ResponseBody
public Object addUser(@RequestBody User user)
{
    System.out.println(user.getName() + " " + user.getAge());
    return new HashMap<String, String>().put("success", "true");
}

 这里的POJO如下：

public class User {
    private String name;
    private String age;

    //getter setter
}

 

2）而在前台，我们可以用 jQuery 来处理 JSON。从这里，我得到了一个 jQuery 的插件，可以将一个表单的数据返回成JSON对象：

$.fn.serializeObject = function(){
    var o = {};
    var a = this.serializeArray();
    $.each(a, function(){
        if (o[this.name]) {
            if (!o[this.name].push) {
                o[this.name] = [o[this.name]];
            }
            o[this.name].push(this.value || '');
        }
        else {
            o[this.name] = this.value || '';
        }
    });
    return o;
};

 

   以下是使用 jQuery 接收、发送 JSON 的代码：

$(document).ready(function(){
    jQuery.ajax({
        type: 'GET',
        contentType: 'application/json',
        url: 'jsonfeed.do',
        dataType: 'json',
        success: function(data){
            if (data && data.status == "0") {
                $.each(data.data, function(i, item){
                    $('#info').append("姓名：" + item.name +"，年龄：" +item.age);
                });
            }
        },
        error: function(){
            alert("error")
        }
    });
    $("#submit").click(function(){
        var jsonuserinfo = $.toJSON($('#form').serializeObject());
        jQuery.ajax({
            type: 'POST',
            contentType: 'application/json',
            url: 'add.do',
            data: jsonuserinfo,
            dataType: 'json',
            success: function(data){
                alert("新增成功！");
            },
            error: function(){
                alert("error")
            }
        });
    });
});

 

但是似乎用Spring这套东西真是个麻烦的事情，相对Jersey对RESTful的实现来看，确实有很多不简洁的地方。

 

 

参考：

官方文档：http://static.springsource.org/spring/docs/3.0.0.M3/spring-framework-reference/html/ch18.html

badqiu的BOLG: 《spring REST中的内容协商(同一资源,多种展现:xml,json,html)》

liuweifeng的BOLG ：http://blog.liuweifeng.net/archives/407

Gary Mark等的书籍：《Spring Recipes》2ed