用Spring MVC搭建REST Service

REST Service即REST(Representational State Transfer表述性状态转移)是一种针对网络应用的设计和开发方式，可以降低开发的复杂性，提高系统的可伸缩性。因此，在许多系统的开发中都需要搭建REST Service。本文我们就来说说如何用Spring MVC搭建REST Service。

随着互联网技术的兴起，XML越来越令人诟病，XML的数据包越来重，SOAP协议方便性和灵活性都有欠缺，尤其兴起的Web2.0发展，由Yahoo、Google 和 Facebook等大型互联网公司的倡导，REST代表性状态传输（Representational State Transfer，REST）在 Web 领域已经得到了广泛的接受，是基于 SOAP 和 Web 服务描述语言（Web Services Description Language，WSDL）的 Web 服务的更为简单的替代方法。下面是Spring MVC搭建REST Service的大概流程。

1.配置pom.xml

pom.xml的配置由于代码量庞大，且是固定的配置，可以自行在网上查阅拷贝。

2.配置web.xml

配置代码如下：

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 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_2_5.xsd">
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:root-context.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>
    </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>appServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:servlet-context.xml</param-value>
        </init-param>
        <load-on-startup>0</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>appServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

</web-app>

  3. servlet-context.xml (关键配置)

<?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:mvc="http://www.springframework.org/schema/mvc"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
        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">

    <mvc:annotation-driven />
    <context:component-scan base-package="com.cnblogs.yjmyzz" />
    <mvc:resources mapping="/resources/**" location="/resources/" />


    <bean
        class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
        <property name="order" value="1" />
        <property name="favorParameter" value="false" />
        <property name="ignoreAcceptHeader" value="true" />
        <property name="defaultContentType" value="text/html" />
        <property name="mediaTypes">
            <map>
                <entry key="json" value="application/json" />
                <entry key="xml" value="application/xml" />
            </map>
        </property>
        <property name="viewResolvers">
            <list>
                <bean class="org.springframework.web.servlet.view.BeanNameViewResolver" />
                <bean
                    class="org.springframework.web.servlet.view.InternalResourceViewResolver">
                    <property name="prefix" value="/WEB-INF/views/" />
                    <property name="suffix" value=".jsp" />
                </bean>
            </list>
        </property>
        <property name="defaultViews">
            <list>
                <bean id="jsonView"
                    class="org.springframework.web.servlet.view.json.MappingJacksonJsonView" />
                <bean id="xmlView"
                    class="org.springframework.web.servlet.view.xml.MarshallingView">
                    <constructor-arg>
                        <bean class="org.springframework.oxm.jaxb.Jaxb2Marshaller">
                            <property name="classesToBeBound">
                                <list>
                                    <value>com.cnblogs.yjmyzz.dto.UserInfo</value>
                                    <value>com.cnblogs.yjmyzz.dto.ListBean</value>
                                </list>
                            </property>
                        </bean>
                    </constructor-arg>
                </bean>
            </list>
        </property>
    </bean>

</beans>

4.DTO对象

package com.cnblogs.yjmyzz.dto;

 

import java.io.Serializable;

import java.math.BigDecimal;

import java.util.Date;

 

import javax.xml.bind.annotation.XmlElement;

import javax.xml.bind.annotation.XmlRootElement;

 

import com.cnblogs.yjmyzz.utils.DateUtil;

import com.cnblogs.yjmyzz.utils.ListUtil;

 

@XmlRootElement(name = "user")

public class UserInfo implements Serializable {

 

    private static final long serialVersionUID = -5461373449802431627L;

    private String userName;

    private BigDecimal salary;

    private Date birthday;

    private boolean isVip;

    private int id;

    private ListBean hobbies;

 

    @XmlElement

    public String getUserName() {

        return userName;

    }

 

    public void setUserName(String userName) {

        this.userName = userName;

    }

 

    @XmlElement

    public BigDecimal getSalary() {

        return salary;

    }

 

    public void setSalary(BigDecimal salary) {

        this.salary = salary;

    }

 

    @XmlElement

    public Date getBirthday() {

        return birthday;

    }

 

    public void setBirthday(Date birthday) {

        this.birthday = birthday;

    }

 

    @XmlElement

    public boolean isVip() {

        return isVip;

    }

 

    public void setVip(boolean isVip) {

        this.isVip = isVip;

    }

 

    @XmlElement

    public int getId() {

        return id;

    }

 

    public void setId(int id) {

        this.id = id;

    }

 

    @XmlElement

    public ListBean getHobbies() {

        return hobbies;

    }

 

    public void setHobbies(ListBean hobbies) {

        this.hobbies = hobbies;

    }

 

    public String toString() {

        return "id:" + this.id + ",userName:" + this.userName + ",isVip="

                + this.isVip + ",birthday="

                + DateUtil.formatDate(this.birthday) + ",hobbies:"

                + ListUtil.getString(this.hobbies.getList());

    }

 

}

为了实现List的XML序列化，还需要一个辅助类ListBean

5.Controller

package com.cnblogs.yjmyzz.web.controller;

 

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

 

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.PathVariable;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

 

import com.cnblogs.yjmyzz.dto.ListBean;

import com.cnblogs.yjmyzz.dto.UserInfo;

import com.cnblogs.yjmyzz.service.UserService;

 

@Controller

@RequestMapping(value = "/rest", method = RequestMethod.GET)

public class RestController {

 

    @Autowired

    UserService userService;

 

    @RequestMapping(value = "/user/{id}", method = RequestMethod.GET)

    public UserInfo show(@PathVariable int id, HttpServletRequest request,

            HttpServletResponse response) throws Exception {

        return userService.getUserInfo(id);

 

    }

 

    @RequestMapping(value = "/user/list", method = RequestMethod.GET)

    public ListBean getAll() throws Exception {

        return userService.getAllUsers();

    }

 

}

上面详细地介绍了Spring MVC搭建REST Service的各个配置情况，按照上述的合理配置就可以成功的用Spring MVC搭建REST Service。Rest Service 相比Web Service建议的标准更轻量级，甚到用Java script都可以调用，使用方更方便、高效、简单。