首先，

直接来web.xml文件

<?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>springmvc-api</display-name>

	<!-- 字符编码过滤 -->
	<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>

	<!-- Spring 配置 -->
	<listener>
		<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
	</listener>
	<context-param>
		<param-name>contextConfigLocation</param-name>
		<param-value>classpath:applicationContext.xml</param-value>
	</context-param>

	<!-- Spring MVC 配置 -->
	<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:applicationContext.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>

其次，
springMVC配置，默认[<servlet-name>]-servlet.xml，个人仍然喜欢自己命名，applicationContext.xml
由于只是API，返回JSON格式，所以就不配置页面等等了，下面这个配置，会自动把返回的对象转换成JSON格式返回

<?xml  version="1.0" encoding="UTF-8"?>
<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-3.1.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd
		http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.1.xsd">

	<!-- 扫描路径 -->
	<context:component-scan base-package="com.study.api" />

	<!-- 添加注解驱动 -->
	<mvc:annotation-driven>
		<mvc:message-converters register-defaults="false">
			<bean
				class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter">
				<property name="supportedMediaTypes">
					<list>
						<!-- 避免IE返回时出现下载提示！ -->
						<value>text/html;charset=UTF-8</value>
						<value>application/json;charset=UTF-8</value>
					</list>
				</property>
			</bean>
		</mvc:message-converters>
	</mvc:annotation-driven>

</beans>

配置就这么多，下面就是Java代码了

UserController.java

package com.study.api.controller;

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

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 org.springframework.web.bind.annotation.ResponseBody;

import com.study.api.vo.UserVO;

@Controller
@RequestMapping("/v1/users")
public class UserController {

	private static List<UserVO> lists = null;

	static {
		lists = new ArrayList<UserVO>();
		UserVO user = new UserVO();
		user.setId("1");
		user.setName("张三");
		UserVO user2 = new UserVO();
		user2.setId("2");
		user2.setName("李四");
		lists.add(user);
		lists.add(user2);
	}

	@RequestMapping(method = RequestMethod.GET)
	@ResponseBody
	public List<UserVO> listUser() {
		return lists;
	}

	@RequestMapping(value = "/{id}", method = RequestMethod.GET)
	@ResponseBody
	public UserVO findUserById(@PathVariable("id") String id) {
		for (UserVO userVO : lists) {
			if (userVO.getId().equals(id)) {
				return userVO;
			}
		}
		return new UserVO();
	}

	@RequestMapping(method = RequestMethod.POST)
	@ResponseBody
	public UserVO insertUser() {
		return null;
	}

	@RequestMapping(value = "/{id}", method = RequestMethod.PUT)
	@ResponseBody
	public UserVO updateUser(@PathVariable("id") String id) {
		return null;
	}
}

UserVO.java

package com.study.api.vo;

public class UserVO {

	private String id;
	private String name;

	public String getId() {
		return id;
	}

	public void setId(String id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

}

注：springmvc整合fastjson返回json格式，对版本有要求，

fastjson要求1.1.33及以上吧，我用的是1.1.41可行

spring要求版本不能太高好像，据说高版本消息装换器只能支持jackjson，我开始用户3.2.4.RELEASE不行，后来换到3.1.1.RELEASE可行

项目（maven）源码：http://download.csdn.net/detail/kaixinkuaikuailai/9426629

项目（maven）jar包：http://download.csdn.net/detail/kaixinkuaikuailai/9426631

完

注：fastjson在1.2.24以及之前版本曝出代码执行漏洞，建议更新，亲试fastjson-1.2.29+Spring-xxx-4.1.6.RELEASE可行