使用Spring MVC 4构建Restful服务
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/
<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.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/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.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;
}
}
5. 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;
@RestController
public 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;
}
}
6.运行结果如下：
