Spring MVC模型保留了之前请求相同映射的属性

Question

当我测试一个控制器时，我发现下面的代码可以正常工作。但我不明白为什么模型在映射后返回后包含“PasspProperty”属性。PasspProperty类仅使用验证约束进行注释。在控制器中，它只在方法中使用@Valid annotation进行注释，如下面的代码所示。

我在控制器中有以下映射：

获取：

@GetMapping("/accounts/change-password")
public ModelAndView changePass(Principal principal) {
    ModelAndView mv = new ModelAndView("change-password");
    mv.addObject("passProperties", new PassProperties());

    return mv;
}

帖子：

@PostMapping("/accounts/change-password")
public ModelAndView changePass(@Valid PassProperties passProperties, BindingResult bindingResult, Principal principal) {
    ModelAndView mv = new ModelAndView("change-password");

    if (bindingResult.hasErrors() == false) {
        User user = userService.findUser(principal.getName());
        String oldPass = passProperties.getOldPass();

        if (encoder.matches(oldPass, user.getPassword())) {
            user.setPassword(encoder.encode(passProperties.getNewPass1()));
            userService.saveUser(user);
            mv.addObject("msg", "Hasło zostało zmienione");
        } else {
            mv.addObject("msg", "Stare hasło nie pasuje.");
        }

    }

    return mv;
}

我添加了以下测试和输出。如您所见，返回的ModelAndView包含未添加到@PostMapping方法中的PasspProperty。PasspProperty对象仅用@Valid注释，PasspProperty类中的字段用约束@NotNull、@Length和@NotBlank注释。它不会在任何地方用@ModelAttribute之类的东西进行注释。测试：

@Test
void changePassPost_whenPassPropertiesHasNoErrors_returnsModelWithPassProperties_And_ChangesPassword() throws Exception {
    User principal = new User ("user", "user", true, "LVL99");

    PassProperties passProperties = new PassProperties();
    passProperties.setOldPass("user");
    passProperties.setNewPass1("zaq1");
    passProperties.setNewPass2("zaq1");

    when(userService.findUser("user")).thenReturn(principal);
    when(encoder.encode(passProperties.getNewPass1())).thenReturn(passProperties.getNewPass1());
    when(encoder.matches(anyString(),anyString())).thenReturn(true);

    ModelAndView mv = mockMvc.perform(MockMvcRequestBuilders.post("/accounts/change-password")
                .with(SecurityMockMvcRequestPostProcessors.csrf())
                .with(SecurityMockMvcRequestPostProcessors.user(new UserDetailsImpl(principal)))
                .param("oldPass", passProperties.getOldPass())
                .param("newPass1", passProperties.getNewPass1())
                .param("newPass2", passProperties.getNewPass2())
            )
            .andDo(MockMvcResultHandlers.print())
            .andExpect(MockMvcResultMatchers.status().isOk())
            .andExpect(MockMvcResultMatchers.model().attributeExists("passProperties"))
            .andExpect(MockMvcResultMatchers.model().hasNoErrors())
            .andExpect(MockMvcResultMatchers.view().name("change-password"))
            .andReturn().getModelAndView();

    System.out.println("-------------------------------");
    System.out.println(mv.getModel().get("passProperties"));
    System.out.println(mv.getModel().get("msg"));
    System.out.println("-------------------------------");

    ArgumentCaptor<User> userCaptor = ArgumentCaptor.forClass(User.class);
    verify(encoder, times(1)).encode(passProperties.getNewPass1());
    verify(userService, times(1)).saveUser(userCaptor.capture());
    assertEquals(passProperties.getNewPass1(), userCaptor.getValue().getPassword());
    assertEquals(passProperties.getNewPass1(), principal.getPassword());

}

输出：

MockHttpServletRequest:
      HTTP Method = POST
      Request URI = /accounts/change-password
       Parameters = {oldPass=[user], newPass1=[zaq1], newPass2=[zaq1], _csrf=[8fc305ee-f0eb-42a6-8588-cce3ffdba469]}
          Headers = []
             Body = null
    Session Attrs = {SPRING_SECURITY_CONTEXT=org.springframework.security.core.context.SecurityContextImpl@a37a47df: Authentication: org.springframework.security.authentication.UsernamePasswordAuthenticationToken@a37a47df: Principal: com.example.JabaVeans.service.UserDetailsImpl@58e46572; Credentials: [PROTECTED]; Authenticated: true; Details: null; Granted Authorities: LVL99}

Handler:
             Type = com.example.JabaVeans.controller.AccountsController
           Method = com.example.JabaVeans.controller.AccountsController#changePass(PassProperties, BindingResult, Principal)

Async:
    Async started = false
     Async result = null

Resolved Exception:
             Type = null

ModelAndView:
        View name = change-password
             View = null
        Attribute = passProperties
            value = PassProperties(oldPass=user, newPass1=zaq1, newPass2=zaq1)
           errors = []
        Attribute = msg
            value = Hasło zostało zmienione

FlashMap:
       Attributes = null

MockHttpServletResponse:
           Status = 200
    Error message = null
          Headers = [Content-Language:"en", Content-Type:"text/html;charset=UTF-8", X-Content-Type-Options:"nosniff", X-XSS-Protection:"1; mode=block", Cache-Control:"no-cache, no-store, max-age=0, must-revalidate", Pragma:"no-cache", Expires:"0", X-Frame-Options:"DENY"]
     Content type = text/html;charset=UTF-8
             Body = <!DOCTYPE html>

    Forwarded URL = null
   Redirected URL = null
          Cookies = []
-------------------------------
PassProperties(oldPass=user, newPass1=zaq1, newPass2=zaq1)
Hasło zostało zmienione
-------------------------------

2020-08-22 18:01:49.655  INFO 12964 --- [extShutdownHook] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Shutdown initiated...
2020-08-22 18:01:49.665  INFO 12964 --- [extShutdownHook] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Shutdown completed.

Process finished with exit code 0

我知道，我可以覆盖"PassProperties"与新的PassProperties在@Post映射擦除以前的值，但我真的很困惑为什么它会发生。

Answer 1

如果您检查PassProperties类，也许它有一些验证注释，如@NotNull、@Min、@Max、@Email、@size等。使用控制器中的@Valid注释，Spring将根据您在类中定义的验证注释检查PassProperties对象是否有效。如果PassProperties对象的某些字段无效，该方法将不会启动，Spring将返回一个基于其中的错误。

我相信PassProperties有一些与密码相关的属性，比如oldPass、newPass。基于你的代码，@GetMap的方法Change ePass只是返回一个新的PassProperties类对象实例。ChangePass的@Post映射正在接收一个PassProperties对象，可能是由某个用户发送的，在这种情况下，就像我上面解释的那样，只有当所有验证都是真的（因为@Valid注释）时才会工作。