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springmvc Rest風格介紹及實現(xiàn)代碼示例

更新時間：2017年11月23日 14:26:58 作者：RexFang

這篇文章主要介紹了springmvc Rest風格介紹及實現(xiàn)代碼示例，rest風格簡潔，分享了HiddenHttpMethodFilter 的源碼，通過Spring4.0實現(xiàn)rest風格源碼及簡單錯誤分析，具有一定參考價值，需要的朋友可以了解下。

簡介

　　REST 即 Representational State Transfer。（資源）表現(xiàn)層狀態(tài)轉(zhuǎn)化。是目前最流行的一種互聯(lián)網(wǎng)軟件架構(gòu)。它結(jié)構(gòu)清晰、符合標準、易于理解、擴展方便，所以正得到越來越多網(wǎng)站的采用，POST, DELETE, PUT, GET 分別對應(yīng) CRUD。Spring3.0 開始支持 REST 風格的請求，是通過 org.springframework.web.filter.HiddenHttpMethodFilter 把 POST 請求轉(zhuǎn)化為 PUT 和 DELETE 請求。本次實驗采用的是 Spring4.0 。

HiddenHttpMethodFilter 源碼

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);
	}
}

　　從 HiddenHttpMethodFilter 的源碼可以看出，Spring 根據(jù)請求中的 _method 參數(shù)進行轉(zhuǎn)化，因此如果想發(fā)起 REST 風格的 DELETE 或者 PUT 請求，只需要在表單中帶上 _method 參數(shù)，并且把 _method 的值設(shè)置為 DELETE 或者 PUT（大寫）即可。詳細例子如下：

在 web.xml 中配置 HiddenHttpMethodFilter
編寫 handler 代碼
編寫頁面

<!-- 配置 org.springframework.web.filter.HiddenHttpMethodFilter ，可以把 POST 請求轉(zhuǎn)化為 PUT 或者 DELETE 請求 -->
  <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")
@Controller
public 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 注解必須加上 required 參數(shù)，否則訪問頁面會出現(xiàn)400錯誤。