springmvc Rest风格介绍及实现代码示例

2019-11-26 10:51:41

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简介

　　REST 即 Representational State Transfer。（资源）表现层状态转化。是目前最流行的一种互联网软件架构。它结构清晰、符合标准、易于理解、扩展方便，所以正得到越来越多网站的采用，POST, DELETE, PUT, GET 分别对应 CRUD。Spring3.0 开始支持 REST 风格的请求，是通过 org.springframework.web.filter.HiddenHttpMethodFilter 把 POST 请求转化为 PUT 和 DELETE 请求。本次实验采用的是 Spring4.0 。

HiddenHttpMethodFilter 源码

public static final String DEFAULT_METHOD_PARAM = "_method";@Override  protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)      throws ServletException, IOException {	String paramValue = request.getParameter(this.methodParam);	if ("POST".equals(request.getMethod()) && StringUtils.hasLength(paramValue)) {		String method = paramValue.toUpperCase(Locale.ENGLISH);		HttpServletRequest wrapper = new HttpMethodRequestWrapper(request, method);		filterChain.doFilter(wrapper, response);	} else {		filterChain.doFilter(request, response);	}}

　　从 HiddenHttpMethodFilter 的源码可以看出，Spring 根据请求中的 _method 参数进行转化，因此如果想发起 REST 风格的 DELETE 或者 PUT 请求，只需要在表单中带上 _method 参数，并且把 _method 的值设置为 DELETE 或者 PUT（大写）即可。详细例子如下：

在 web.xml 中配置 HiddenHttpMethodFilter
编写 handler 代码
编写页面

<!-- 配置 org.springframework.web.filter.HiddenHttpMethodFilter ，可以把 POST 请求转化为 PUT 或者 DELETE 请求 -->  <filter>    <filter-name>HiddenHttpMethodFilter</filter-name>    <filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filter-class>  </filter>  <filter-mapping>    <filter-name>HiddenHttpMethodFilter</filter-name>    <url-pattern>/*</url-pattern>  </filter-mapping>

package rex.springmvc.handlers;import org.apache.log4j.Logger;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import org.springframework.web.bind.annotation.RequestParam;@RequestMapping(value="/restTest")@Controllerpublic class RestTestHandler {	private static final Logger logger = Logger.getLogger(RestTestHandler.class);	private static final String SUCCESS = "success";	@RequestMapping(value="/restGet/{id}", method=RequestMethod.GET)	  public String restGet(@RequestParam(value="id", required=false) Integer id){		logger.debug("restGet:" + id);		return SUCCESS;	}	@RequestMapping(value="/restPut/{id}", method=RequestMethod.PUT)	  public String restPut(@RequestParam(value="id", required=false) Integer id){		logger.debug("restPut:" + id);		return SUCCESS;	}	@RequestMapping(value="/restDelete/{id}", method=RequestMethod.DELETE)	  public String restDelete(@RequestParam(value="id", required=false) Integer id){		logger.debug("restDelete:" + id);		return SUCCESS;	}	@RequestMapping(value="/restPost", method=RequestMethod.POST)	  public String restPost(){		logger.debug("restPost");		return SUCCESS;	}}

<%@ page language="java" contentType="text/html; charset=UTF-8"  pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Rest Test</title></head><body>  <br>  <br>  <a href="restTest/restGet/1" rel="external nofollow" >Test Rest Get</a>  <br>  <br>  <form action="restTest/restPut/1" method="post">    <input type="hidden" name="_method" value="PUT"> <input      type="submit" value="submit">  </form>  <br>  <br>  <form action="restTest/restDelete/1" method="post">    <input type="hidden" name="_method" value="DELETE"> <input      type="submit" value="submit">  </form>  <br>  <br>  <form action="restTest/restPost" method="post">    <input type="submit" value="submit">  </form></body></html>

注：handler 中 @RequestParam 注解必须加上 required 参数，否则访问页面会出现400错误。