使用Spring MVC 4构建Restful服务

原文地址：http://bbs.51cto.com/thread-1131636-1.html

使用Spring MVC 4构建RESTful服务相对于其它框架来说，有很多优势。首先，Spring MVC 4作为Spring的框架之一，可以很好地与Spring进行集成。其次，Spring MVC 4的拦截器是在方法层级上的拦截，相对于其它MVC框架（如Struts2）的拦截器具有更高的效率。再者，Spring MVC 4采用基于注解的配置，入手容易，开发灵活。

Spring MVC 4采用的是jacson解析JSON。jacson一款非常高效强大的JSON工具类，可以轻松地在JAVA对象与json对象和XML文档之间进行序列化和反序列化。本文中的例子采用的是Spring 4.1.1.RELEASE和jacson 2.4.0版本，经测试无任何异常。接下来，上干货：开发环境准备：    Eclipse Luna    Apache Tomcat 8.0    JDK 1.7    Spring 4.1.1.RELEASE    jackson 2.4.0工程目录如下：1. 新建Maven Project，选择在“Archetype类型”中，选择“maven-archetype-webapp”。2. 在Pom.xml中添加

Maven 依赖，从而可以使用 Spring和jackson中的特性。如果读者使用的是Dynamic Web Project，可以从Maven仓库下载对的Spring Jar和 jacson jar。

Spring的Maven仓库地址：http://repo1.maven.org/maven2/org/springframework/jackson的Maven仓库地址：http://repo1.maven.org/maven2/com/fasterxml/jackson/core/

<projectxmlns="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.favccxx.favsoft</groupId>  <artifactId>favspringmvcrestful</artifactId>  <packaging>war</packaging>  <version>0.0.1-SNAPSHOT</version>  <name>favspringmvcrestful Maven Webapp</name>  <url>http://maven.apache.org</url>  <properties>      <spring.version>4.1.1.RELEASE</spring.version>      <jackson.version>2.4.0</jackson.version>  </properties>  <dependencies>    <dependency>      <groupId>junit</groupId>      <artifactId>junit</artifactId>      <version>3.8.1</version>      <scope>test</scope>    </dependency>    <dependency>        <groupId>org.springframework</groupId>        <artifactId>spring-core</artifactId>        <version>${spring.version}</version>    </dependency>    <dependency>        <groupId>org.springframework</groupId>        <artifactId>spring-webmvc</artifactId>        <version>${spring.version}</version>    </dependency>    <dependency>        <groupId>org.springframework</groupId>        <artifactId>spring-beans</artifactId>        <version>${spring.version}</version>    </dependency>    <dependency>        <groupId>org.springframework</groupId>        <artifactId>spring-context</artifactId>        <version>${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>  </dependencies>  <build>    <finalName>favspringmvcrestful</finalName>  </build></project>

3.在 web.xml中，配置Spring MVC 4 的DispatcherServlet转发和编码。

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee     http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">    <display-name>favblog</display-name>    <context-param>        <param-name>contextConfigLocation</param-name>        <param-value></param-value>    </context-param>    <filter>        <filter-name>encodingFilter</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>encodingFilter</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-context.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>

<?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/s ... ing-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.favccxx.favsoft.favjson.controller"></context:component-scan>    <mvc:annotation-driven></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/views" />        <property name="suffix" value=".jsp" />    </bean></beans>

4.新建 FavUser.java 类，测试JSON与Object之间的映射。需要注意的是，如果想对日期进行格式化，在其Getter方法上，使用 @JsonFormat 即可，这样就能输出符合pattern类型的日期，但是这同时也要求输入的日期参数也必须是pattern类型的。

package com.favccxx.favsoft.favjson.pojo;import java.util.Date;import com.fasterxml.jackson.annotation.JsonFormat;public class FavUser {    private String userId;    private String userName;    private int userAge;    private Date createDate;    public String getUserId() {        return userId;    }    public void setUserId(String userId) {        this.userId = userId;    }    public String getUserName() {        return userName;    }    public void setUserName(String userName) {        this.userName = userName;    }    public int getUserAge() {        return userAge;    }    public void setUserAge(int userAge) {        this.userAge = userAge;    }    @JsonFormat(pattern="yyyy-MM-dd HH:mm:ss")    public Date getCreateDate() {        return createDate;    }    public void setCreateDate(Date createDate) {        this.createDate = createDate;    }}

1. 新建FavRestfulController，通过不同的方法测试Spring MVC 4 返回String、Object类型的JSON。

package com.favccxx.favsoft.favjson.controller;import java.io.IOException;import org.springframework.web.bind.annotation.RequestBody;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import org.springframework.web.bind.annotation.RequestParam;import org.springframework.web.bind.annotation.RestController;import com.fasterxml.jackson.core.JsonParseException;import com.fasterxml.jackson.databind.JsonMappingException;import com.fasterxml.jackson.databind.ObjectMapper;import com.favccxx.favsoft.favjson.pojo.FavUser;@RestControllerpublic class FavRestfulController {    @RequestMapping(value="/getUserName",method=RequestMethod.POST)    public String getUserName(@RequestParam(value="name") String name){        return name;    }    @RequestMapping("getFavUser")    public FavUser getFavUser(@RequestParam("userName") String userName,String userId,int userAge){        FavUser favUser = new FavUser();        favUser.setUserId(userId);        favUser.setUserName(userName);        favUser.setUserAge(userAge);        return favUser;    }    @RequestMapping("getFavUserBody")    public FavUser getFavUserBody(@RequestBody String body){        ObjectMapper mapper = new ObjectMapper();        FavUser favUser = null;        try {            favUser = mapper.readValue(body,  FavUser.class);        } catch (JsonParseException e) {            e.printStackTrace();        } catch (JsonMappingException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }        return favUser;    }}