关于SpringMVC拦截器执行两遍的原因分析以及如何解决

 1 package com.atwu.miao.intercepter;
 2 
 3 import com.atwu.miao.service.UserService;
 4 import org.springframework.beans.factory.annotation.Autowired;
 5 import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
 6 
 7 import javax.servlet.http.HttpServletRequest;
 8 import javax.servlet.http.HttpServletResponse;
 9 
10 public class AuthIntercepter extends HandlerInterceptorAdapter {
11 
12     @Autowired
13     private UserService userService;
14 
15     @Override
16     public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
17         String name = request.getParameter("name");
18         String password = request.getParameter("password");
19         return userService.hasUser(name,password);
20     }
21 }

 1 @Controller
 2 public class GreetingController {
 3 
 4     /**
 5      * 第一种情况：方法返回值类型为 void 类型，并且不存在RequestMapping对应的视图
 6      *
 7      * @param name
 8      * @throws IOException
 9      */
10     @RequestMapping("/greet1")
11     public void greet1(String name) throws IOException {
12         System.out.println("name = " + name);
13         RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
14         HttpServletResponse response = ((ServletRequestAttributes) requestAttributes).getResponse();
15         PrintWriter writer = response.getWriter();
16         writer.write(name);
17         writer.flush();
18         writer.close();
19     }
20 
21 
22     /**
23      * 第二种情况：方法返回值类型为 String 类型，并且不存在返回内容对应的视图
24      *
25      * @param name
26      * @return
27      */
28     @RequestMapping("/greet2")
29     public String greet2(String name) {
30         System.out.println("name = " + name);
31         return name;
32     }
33 
34 }

 1 @Configuration
 2 public class MVCConfig extends WebMvcConfigurationSupport {
 3      //自定义的拦截器
 4     @Bean
 5     public SecurityInterceptor getSecurityInterceptor() {
 6         return new SecurityInterceptor();
 7     }
 8   
 9     @Override
10     public void addInterceptors(InterceptorRegistry registry) {
11         //添加拦截器
12         InterceptorRegistration registration = registry.addInterceptor(getSecurityInterceptor());
13         //排除的路径
14         registration.excludePathPatterns("/login");
15         registration.excludePathPatterns("/logout");
16         //将这个controller放行
17         registration.excludePathPatterns("/error");
18         //拦截全部
19         registration.addPathPatterns("/**");
20     }
21 }

 1 public class CustomizedHandlerAdapter extends RequestMappingHandlerAdapter {
 2 
 3     @Override
 4     public void afterPropertiesSet() {
 5         super.afterPropertiesSet();
 6         setReturnValueHandlers(getReturnValueHandlers().stream().filter(
 7                 h -> h.getClass() != ViewNameMethodReturnValueHandler.class
 8         ).collect(Collectors.toList()));
 9     }
10 }
11 
12 public class HandlerVoidMethod extends ViewNameMethodReturnValueHandler {
13 
14     @Override
15     public void handleReturnValue(Object returnValue, MethodParameter returnType, ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception {
16         /*
17          * 这里只处理了void返回值的方法，对于String返回值的方法则没有处理，原因是系统中可能还会用到springmvc的视图功能（例如jsp）
18          * 如果说是前后分离的项目，springmvc层只提供纯接口的话，那么可以将下面代码全部删除，
19          * 只写上一行  mavContainer.setRequestHandled(true);  即可
20          */
21         if (void.class == returnType.getParameterType()) {
22             mavContainer.setRequestHandled(true);//这行代码是重点，它的作用是告诉其他组件本次请求已经被程序内部处理完毕，可以直接放行了
23         } else {
24             super.handleReturnValue(returnValue, returnType, mavContainer, webRequest);
25         }
26     }
27 }
28 
29 @Configuration
30 public class WebConfig {
31 
32     @Bean
33     public HandlerVoidMethod handlerVoidMethod() {
34         return new HandlerVoidMethod();
35     }
36 
37     @Bean
38     public CustomizedHandlerAdapter handlerAdapter(HandlerVoidMethod handlerVoidMethod) {
39         CustomizedHandlerAdapter chl = new CustomizedHandlerAdapter();
40         chl.setCustomReturnValueHandlers(Arrays.asList(handlerVoidMethod));
41         return chl;
42     }
43 }