Rest使用

REST

<span style="font-family:SimSun;">REST（英文：Representational State Transfer)。REST描述了一个架构样式的网络系统，比如 web 应用程序。它首次出现在 2000 年 Roy Fielding 的博士论文中。使用的是标准的 HTTP 方法，比如 GET、PUT、POST和DELETE.REST 简化了客户端和服务器的实现.</span>

表现层

<span style="font-family:SimSun;">REST的名称"表现层状态转化"。"表现层"其实指的是"资源"（Resources）的"表现层"。所谓"资源"，就是网络上的一个实体，或者说是网络上的一个具体信息。可以是任意mime type。另外，URI只代表资源的实体，不代表它的形式，确切的说，URI应该只代表"资源"的位置。它的具体表现形式，应该在HTTP请求的头信息中用Accept和Content-Type字段指定，这两个字段才是对"表现层"的描述。下面通过一个Web例子说明>首先要准备REST所需的jar包，这里交给maven。</span>

<span style="white-space:pre"></span><dependency><groupId>org.codehaus.jackson</groupId><artifactId>jackson-mapper-asl</artifactId><version>1.9.3</version></dependency><dependency><groupId>org.codehaus.jackson</groupId><artifactId>jackson-jaxrs</artifactId><version>1.9.13</version></dependency><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-core</artifactId><version>2.7.0</version></dependency>

在spring的配置文件中配置

<?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:context="http://www.springframework.org/schema/context"xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:p="http://www.springframework.org/schema/p"xmlns:aop="http://www.springframework.org/schema/aop"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsd  http://www.springframework.org/schema/mvchttp://www.springframework.org/schema/mvc/spring-mvc.xsd       http://www.springframework.org/schema/context       http://www.springframework.org/schema/context/spring-context.xsd"default-lazy-init="true"><!-- 通过mvc:resources设置静态资源，这样servlet就会处理这些静态资源，而不通过控制器 --><!-- 设置不过滤内容，比如:css,jquery,img 等资源文件 --><mvc:resources location="/*.html" mapping="/**.html" /><mvc:resources location="/css/*" mapping="/css/**" /><mvc:resources location="/js/*" mapping="/js/**" /><mvc:resources location="/images/*" mapping="/images/**" /><!-- 添加注解驱动 --><mvc:annotation-driven /><!-- 默认扫描的包路径 --><context:component-scan base-package="com.my.web.*" /><beanclass="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" /><!-- application/xml --><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" /><beanclass="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.my.web.bean.Employee</value><!-- <value>com.cnblogs.yjmyzz.dto.ListBean</value> --></list></property></bean></constructor-arg></bean></list></property></bean></beans>

注意，defaultContentType 是默认的资源表现形式，常见有“application/json", "application/xml" , "test/html"。

mediatypes用于设置http request请求的数据表现形式转换关系。

为请求编写controller

/** *  */package com.my.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 org.springframework.web.bind.annotation.RequestParam;import org.springframework.web.bind.annotation.ResponseBody;import com.my.web.bean.Employee;import com.my.web.bean.ListBean;import com.my.web.service.EmployeeService;@Controller@RequestMapping(value = "/rest", method = RequestMethod.GET)public class MyController {@AutowiredEmployeeService service;@RequestMapping(value = "/user/{id}", method = RequestMethod.GET)public Employee show(@PathVariable int id, HttpServletRequest request,HttpServletResponse response) throws Exception {return service.getEmployee(id);}}

构造所需数据

package com.my.web.service.impl;import java.math.BigDecimal;import org.springframework.stereotype.Service;import com.my.web.bean.Employee;import com.my.web.service.EmployeeService;@Servicepublic class EmployeeServiceImpl implements EmployeeService {@Overridepublic Employee getEmployee(int id) {return new Employee("hust", new BigDecimal("50"), false, 5);}}

构建Bean

package com.my.web.bean;import java.io.Serializable;import java.math.BigDecimal;import javax.xml.bind.annotation.XmlElement;import javax.xml.bind.annotation.XmlRootElement;@XmlRootElement(name = "employee")public class Employee implements Serializable {private static final long serialVersionUID = 1L;private String userName;private BigDecimal salary;private boolean isVip;private int id;public Employee(String userName, BigDecimal salary,boolean isVip, int id) {this.userName = userName;this.salary = salary;this.isVip = isVip;this.id = id;}public Employee() {}@XmlElementpublic String getUserName() {return userName;}public void setUserName(String userName) {this.userName = userName;}@XmlElementpublic BigDecimal getSalary() {return salary;}public void setSalary(BigDecimal salary) {this.salary = salary;}public boolean isVip() {return isVip;}public void setVip(boolean isVip) {this.isVip = isVip;}@XmlElementpublic int getId() {return id;}public void setId(int id) {this.id = id;}public String toString() {return "id:" + this.id + ",userName:" + this.userName + ",isVip="+ this.isVip;}}

注意：

1. 对元素属性加

@XmlElement

2. 一定要添加默认构造函数

3. 覆写toString()方法（我的是不写会报错）。

为了URI能被rest处理在web.xml修改pattern如下

<servlet><servlet-name>dispatcher</servlet-name><servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class><load-on-startup>1</load-on-startup></servlet><!-- 设置dispatchservlet的匹配模式，通过把dispatchservlet映射到/，默认servlet会处理所有的请求，包括静态资源 --><servlet-mapping><servlet-name>dispatcher</servlet-name><url-pattern>/</url-pattern></servlet-mapping><context-param><param-name>contextConfigLocation</param-name><param-value>/WEB-INF/dispatcher-servlet.xml</param-value></context-param><listener><listener-class>org.springframework.web.context.ContextLoaderListener</listener-class></listener>

启动server，我们就可以通过URI获取我们的资源了。比如http://localhost:8080/restful/rest/user/5.xml。其中.xml我们指定返回资源的表现形式。