SpringBoot之HiddenHttpMethodFilter

本文主要是介绍SpringBoot之HiddenHttpMethodFilter，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

前言

默认情况下，表单只能发送GET、POST请求，如果需要发送PUT、DELETE请求呢？SpringBoot通过 HiddenHttpMethodFilter 解决了这一问题。

演示表单只能发送GET、POST请求

创建user.html

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body><form action="/user" method="get"><input value="GET 提交" type="submit"/></form><form action="/user" method="post"><input value="POST提交" type="submit"/></form><form action="/user" method="put"><input value="DELETE 提交" type="submit"/></form><form action="/user" method="delete"><input value="PUT 提交" type="submit"/></form>
</body>
</html>

页面展示

创建 UserController

@RestController
public class UserController {@GetMapping("/user")public String getUser() {return "get user";}@PostMapping("/user")public String postUser() {return "post user";}@PutMapping("/user")public String putUser() {return "put user";}@DeleteMapping("/user")public String deleteUser() {return "delete user";}
}

发送 GET 请求

发送 POST 请求

发送 DELETE 请求

发送 PUT 请求

我们期望的DELETE、PUT 请求，都转发到GET请求了

通过 HiddenHttpMethodFilter 发送DELETE、PUT 请求

添加配置

spring:mvc:hiddenmethod:filter:enabled: true

修改 user.html

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body><form action="/user" method="get"><input value="GET 提交" type="submit"/></form><form action="/user" method="post"><input value="POST 提交" type="submit"/></form><form action="/user" method="post"><input name="_method" type="hidden" value="DELETE"/><input value="DELETE 提交" type="submit"/></form><form action="/user" method="post"><input name="_method" type="hidden" value="PUT"/><input value="PUT 提交" type="submit"/></form>
</body>
</html>

发送 DELETE 请求

发送 PUT 请求

可以正确发送DELETE、PUT 请求

源码简析

WebMvcAutoConfiguration#hiddenHttpMethodFilter

@Bean
@ConditionalOnMissingBean(HiddenHttpMethodFilter.class)
@ConditionalOnProperty(prefix = "spring.mvc.hiddenmethod.filter", name = "enabled")
public OrderedHiddenHttpMethodFilter hiddenHttpMethodFilter() {return new OrderedHiddenHttpMethodFilter();
}

通过 @ConditionalOnProperty 注解，我们明白需要将 spring.mvc.hiddenmethod.filter.enable 属性设置为 true。

OrderedHiddenHttpMethodFilter 类结构

通过 OrderedHiddenHttpMethodFilter 的类结构，我们可以看出来它继承 HiddenHttpMethodFilter，我们查看相关源码。

public class HiddenHttpMethodFilter extends OncePerRequestFilter {private static final List<String> ALLOWED_METHODS =Collections.unmodifiableList(Arrays.asList(HttpMethod.PUT.name(),HttpMethod.DELETE.name(), HttpMethod.PATCH.name()));/** Default method parameter: {@code _method}. */public static final String DEFAULT_METHOD_PARAM = "_method";private String methodParam = DEFAULT_METHOD_PARAM;/*** Set the parameter name to look for HTTP methods.* @see #DEFAULT_METHOD_PARAM*/public void setMethodParam(String methodParam) {Assert.hasText(methodParam, "'methodParam' must not be empty");this.methodParam = methodParam;}@Overrideprotected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)throws ServletException, IOException {HttpServletRequest requestToUse = request;if ("POST".equals(request.getMethod()) && request.getAttribute(WebUtils.ERROR_EXCEPTION_ATTRIBUTE) == null) {String paramValue = request.getParameter(this.methodParam);if (StringUtils.hasLength(paramValue)) {String method = paramValue.toUpperCase(Locale.ENGLISH);if (ALLOWED_METHODS.contains(method)) {requestToUse = new HttpMethodRequestWrapper(request, method);}}}filterChain.doFilter(requestToUse, response);}/*** Simple {@link HttpServletRequest} wrapper that returns the supplied method for* {@link HttpServletRequest#getMethod()}.*/private static class HttpMethodRequestWrapper extends HttpServletRequestWrapper {private final String method;public HttpMethodRequestWrapper(HttpServletRequest request, String method) {super(request);this.method = method;}@Overridepublic String getMethod() {return this.method;}}}

注意点

DEFAULT_METHOD_PARAM ： _method
ALLOWED_METHODS ： PUT、DELETE、PATCH
HttpMethodRequestWrapper 的 getMethod 方法

通过上述源码我们得出以下结论：如果表单是通过 POST 提交的且存在参数 methodParam （默认 _method），methodParam 参数值如果是 ALLOWED_METHODS 中的一种，则将HttpServletRequest 封装成 HttpMethodRequestWrapper ，这个类会重写 getMethod 方法，方法的返回值就是 methodParam 参数传递过来的值。

请求映射

DispatcherServlet#doDispatch

DispatcherServlet#getHandler

请求一般是由 RequestMappingHandlerMapping 处理的

AbstractHandlerMapping#getHandler

RequestMappingInfoHandlerMapping#getHandlerInternal

AbstractHandlerMethodMapping#getHandlerInternal

AbstractHandlerMethodMapping#lookupHandlerMethod

URI 和具体方法的映射关系，都存储在 mappingRegistry 这个属性中

请求映射的详细解析可以查看这篇博文： SpringBoot之请求映射原理

扩展：自定义HiddenHttpMethodFilter

如果存在自定义的 HiddenHttpMethodFilter，则默认的 HiddenHttpMethodFilter 失效。

创建类 CustomHiddenHttpMethodFilter

public class CustomHiddenHttpMethodFilter extends HiddenHttpMethodFilter {
}

创建配置类 FilterConfig

@Configuration
public class FilterConfig {@Beanpublic CustomHiddenHttpMethodFilter hiddenHttpMethodFilter() {CustomHiddenHttpMethodFilter customHiddenHttpMethodFilter = new CustomHiddenHttpMethodFilter();customHiddenHttpMethodFilter.setMethodParam("_custom");return customHiddenHttpMethodFilter;}
}

修改user.html

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body><form action="/user" method="get"><input value="GET 提交" type="submit"/></form><form action="/user" method="post"><input value="POST 提交" type="submit"/></form><form action="/user" method="post"><input name="_custom" type="hidden" value="DELETE"/><input value="DELETE 提交" type="submit"/></form><form action="/user" method="post"><input name="_custom" type="hidden" value="PUT"/><input value="PUT 提交" type="submit"/></form></body>
</html>