SpringMVC构建Restful。

因为spring是依赖jackson来生成json，需要添加jar包。

pom.xml文件添加依赖。

<dependency>
    <groupId>org.codehaus.jackson</groupId>
    <artifactId>jackson-mapper-asl</artifactId>
    <version>1.9.13</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.5.3</version>
</dependency>

web.xml文件

<?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_3_0.xsd" id="WebApp_ID" version="2.2">
    <display-name>mybatis</display-name>
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:spring-application.xml</param-value>
    </context-param>
    <filter>
        <description>字符集过滤器</description>
        <filter-name>encodingFilter</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <description>字符集编码</description>
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>encodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <listener>
        <description>spring监听器</description>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <!-- 防止spring内存溢出监听器 -->
    <listener>
        <listener-class>org.springframework.web.util.IntrospectorCleanupListener</listener-class>
    </listener>
    <!-- spring mvc servlet -->
    <servlet>
        <description>spring mvc servlet</description>
        <servlet-name>springMvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <description>spring mvc 配置文件</description>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring-mvc.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>
    <!-- 配置session超时时间，单位分钟 -->
    <session-config>
        <session-timeout>15</session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.htm</welcome-file>
        <welcome-file>index.jsp</welcome-file>
        <welcome-file>default.html</welcome-file>
        <welcome-file>default.htm</welcome-file>
        <welcome-file>default.jsp</welcome-file>
    </welcome-file-list>
</web-app>

其中是注意设置spring mvc servlet中拦截请求路径。

spring-application.xml文件

<?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" 
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
">

    <!-- 引入属性文件 -->
    <context:property-placeholder location="classpath:config.properties" />

    <!-- 自动扫描(自动注入) -->
    <context:component-scan base-package="sy.service" />
    
    <import resource="spring-mybatis.xml"/>
    <!-- <import resource="spring-redis.xml"/> -->
    <!-- <import resource="spring-memcached.xml"/>
    <import resource="spring-mongodb.xml"/>
    <import resource="spring-security.xml"/> -->
</beans>

spring-mvc.xml文件

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

    <!-- 自动扫描controller包下的所有类，使其认为spring mvc的控制器 -->
    <context:component-scan base-package="sy.controller" />

    <!-- 避免IE执行AJAX时,返回JSON出现下载文件 -->
    <bean id="mappingJacksonHttpMessageConverter" class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter">
        <property name="supportedMediaTypes">
            <list>
                <value>text/html;charset=UTF-8</value>
            </list>
        </property>
    </bean>

    <!-- 启动Spring MVC的注解功能，完成请求和注解POJO的互相转换映射 输出对象转JSON的支持 -->
    <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
        <property name="messageConverters">
            <list>
                <ref bean="mappingJacksonHttpMessageConverter" /><!-- json转换器 -->
            </list>
        </property>
    </bean>

    <!-- 对模型视图名称的解析，即在模型视图名称添加前后缀 -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" p:prefix="/" p:suffix=".jsp" />

    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="defaultEncoding">
            <value>UTF-8</value>
        </property>
        <property name="maxUploadSize">
            <value>32505856</value><!-- 上传文件大小限制为31M，31*1024*1024 -->
        </property>
        <property name="maxInMemorySize">
            <value>4096</value>
        </property>
    </bean>

</beans>

这个文件中对restful的支持主要是HttpMessageConverter的配置。

HttpMessageConverter接口，需要开启<mvc:annotation-driven  />。

测试Controller编写

pojo类

package sy.model;

import java.util.Date;

public class Myuser {
    private Integer id;

    private String name;

    private String sex;

    public Integer getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name == null ? null : name.trim();
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex == null ? null : sex.trim();
    }

    @Override
    public String toString() {
        return "Myuser [id=" + id + ", name=" + name + ", sex=" + sex
                + ", province=" + province + ", createdate=" + createdate
                + ", updatedate=" + updatedate + "]";
    }
    
}

Controller类

package sy.controller;

import java.io.UnsupportedEncodingException;
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.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

import com.alibaba.fastjson.JSONObject;

import sy.model.Myuser;

@Controller
public class RestfulController {
    
    @RequestMapping(value="/hello",produces = "text/plain;charset=UTF-8")
    public @ResponseBody
    String hello1(){
        return "index";
    }
    
    @RequestMapping(value="/hello")
    String hello2(){
        return "index";
    }
    
    @RequestMapping(value = "/say/{msg}", produces = "application/json;charset=UTF-8")
    public @ResponseBody
    String say(@PathVariable(value = "msg") String msg) {
        return "{\"msg\":\"you say:'" + msg + "'\"}";
    }

    @RequestMapping(value = "/user/{id:\\d+}", method = RequestMethod.GET)
    public @ResponseBody
    Myuser getuser(@PathVariable("id") int id) throws UnsupportedEncodingException {
        Myuser myuser = new Myuser();
        
        myuser.setName("张三");
        myuser.setSex("男");
        myuser.setId(id);
        return myuser;
    }

    @RequestMapping(value = "/user/{id:\\d+}", method = RequestMethod.DELETE)
    public @ResponseBody
    Object deleteuser(@PathVariable("id") int id) {
        JSONObject jsonObject = new JSONObject();
        jsonObject.put("msg", "删除人员信息成功");
        return jsonObject;
    }

    @RequestMapping(value = "/user", method = RequestMethod.POST)
    public @ResponseBody
    Object adduser(Myuser user) {
        JSONObject jsonObject = new JSONObject();
        jsonObject.put("msg", "注册人员信息成功");
        return jsonObject;
    }

    @RequestMapping(value = "/user", method = RequestMethod.PUT)
    public @ResponseBody
    Object updateuser(Myuser user) {
        JSONObject jsonObject = new JSONObject();
        jsonObject.put("msg", "更新人员信息成功");
        return jsonObject;
    }

    @RequestMapping(value = "/user", method = RequestMethod.PATCH)
    public @ResponseBody
    List<Myuser> listuser(@RequestParam(value = "name", required = false, defaultValue = "") String name) {

        List<Myuser> lstusers = new ArrayList<Myuser>();

        Myuser myuser = new Myuser();
        myuser.setName("张三");
        myuser.setSex("男");
        myuser.setId(101);
        lstusers.add(myuser);

        Myuser myuser2 = new Myuser();
        myuser2.setName("李四");
        myuser2.setSex("女");
        myuser2.setId(102);
        lstusers.add(myuser2);

        Myuser myuser3 = new Myuser();
        myuser3.setName("王五");
        myuser3.setSex("男");
        myuser3.setId(103);
        lstusers.add(myuser3);

        return lstusers;
    }
    
}

restful的实现主要是依赖@ResponseBody、@RequestBody注解和HttpMessageConverter来实现pojo对象和对应协议的转换。

Spring 3.X系列增加了新注解@ResponseBody，@RequestBody 

• @RequestBody 将HTTP请求正文转换为适合的HttpMessageConverter对象。
• @ResponseBody 将内容或对象作为 HTTP 响应正文返回，并通过Adapter调用合适的HttpMessageConverter来转换对象，写入HttpResponse输出流，返回给浏览器。

HttpMessageConverter接口，需要开启<mvc:annotation-driven  />。 
AnnotationMethodHandlerAdapter将会初始化7个转换器，可以通过调用AnnotationMethodHandlerAdapter的getMessageConverts()方法来获取转换器的一个集合 List<HttpMessageConverter> 

引用

ByteArrayHttpMessageConverter 
StringHttpMessageConverter 
ResourceHttpMessageConverter 
SourceHttpMessageConverter 
XmlAwareFormHttpMessageConverter 
Jaxb2RootElementHttpMessageConverter 
MappingJacksonHttpMessageConverter

有关@ResponseBody，@RequestBody，@PathVariable 的详细信息，参考《@ResponseBody，@RequestBody，@PathVariable 》

比如上述controller中的hello1和hello2方法，其中hello1使用了注解@ResponseBody，那么会将string通过httpMsessageConverter直接转换，写入response；而hello2方法没有使用注解，那么就会根据spring-mvc.xml中配置的解析器，寻找jsp页面，并写入response，返回给浏览器。

 

总结：

　　1.和springmvc配置不一样的地方主要是controller中的方法也是用@ResponseBody注解，将Object转成相对应的协议（一般是xml和json）写入到response中，返回给浏览器。

　　2.一定要开启<mvc:annotation-driven  />

　　3.方法RequestMapping设置一定要遵循Restful规范风格。