- 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")
@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">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。
