SpringBoot常用注解目录

• 一@Controller和@RestController
• 二@RequestParam和@RequestBody
• 三@PathVariable
• @Valid和Validated

一@Controller和@RestController

@Controller中的方法一般返回HTML的名字，跳转到HTML页面
@RestController中的方法一般返回 String串或者Json串 返回的是数据
@RestController相当于是 @Controller + @ResponseBody

如果想要返回到某个页面并且要携带Json数据则只能用@Controller 并在方法上面加@ResponseBody

二@RequestParam和@RequestBody

1 RequestParam将请求中URL的参数绑定到方法的形参中
http://localhost:8080/hello?name=你好

@Controller
public class HelloController {
@RequestMapping("/hello")
public String hello(Model model, @RequestParam(value="name", required=false, defaultValue="World") String cxname) {
model.addAttribute("name", cxname);
return "hello";
}
}

2 RequestBody用于获取post提交中的参数，把提交的json转化为实体类

三@PathVariable

@PathVariable从restful风格的URL中获取请求参数

@RequestMapping("/rest/{name}")
public String resthello(Model model,  @PathVariable String name) {
model.addAttribute("name", name);
return "hello";
}

从浏览器访问

@Valid和Validated

@Valid是使用hibernate validation的时候使用
@Validated 是只用spring Validator 校验机制使用
用于验证表单提交的数据
@Validated @Valid 和BindingResult bindingResult是配对出现，并且形参顺序是固定的（一前一后）。

controller

@PostMapping
public ModelAndView create(@Valid Message message, BindingResult result,
RedirectAttributes redirect) {
if (result.hasErrors()) {
return new ModelAndView("messages/form", "formErrors", result.getAllErrors());
}
message = this.messageRepository.save(message);
redirect.addFlashAttribute("globalMessage", "Successfully created a new message");
return new ModelAndView("redirect:/{message.id}", "message.id", message.getId());
}

前台表单

<form id="messageForm" th:action="@{/(form)}" th:object="${message}" action="#" method="post">
<div th:if="${#fields.hasErrors('*')}" class="alert alert-danger" role="alert">
<p th:each="error : ${#fields.errors('*')}" class="m-0" th:text="${error}">Validation error</p>
</div>
<input type="hidden" th:field="*{id}" th:class="${'form-control' + (#fields.hasErrors('id') ? ' is-invalid' : '')}"/>
<div class="form-group">
<label for="summary">Summary</label>
<input type="text" th:field="*{summary}" th:class="${'form-control' + (#fields.hasErrors('summary') ? ' is-invalid' : '')}">
</div>
<div class="form-group">
<label for="text">Message</label>
<textarea th:field="*{text}" th:class="${'form-control' + (#fields.hasErrors('text') ? ' is-invalid' : '')}"></textarea>
</div>
<button type="submit" class="btn btn-primary">Submit</button>
</form>

实体类需要加相应的限制 有哪些注解请查看
valid验证实体类中字段

public class Message {

private Long id;

@NotEmpty(message = "Text is required.")
private String text;

@NotEmpty(message = "Summary is required.")
private String summary;