1. @RequestParam 注解
- 将请求的查询参数绑定到控制器方法的参数上
@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface RequestParam {
@AliasFor("name")
String value() default "";
@AliasFor("value")
String name() default "";
boolean required() default true;
String defaultValue() default ValueConstants.DEFAULT_NONE;
}
name, value 属性：
指定要绑定的请求参数名
required 属性：
required 默认为true, 若不传该参数，则会抛出异常
defaultValue 属性
当请求中没有提供相应参数时，使用此默认值
1.2 示例
/**
* RUL: http://localhost:8080/web/params?id=1001&code=AAA
*/
@RequestMapping("/params")
public String params(@RequestParam("id") String id, @RequestParam("code") String orderCode,
@RequestParam(value = "name", defaultValue = "Tinyspot") String name,
@RequestParam(value = "field", required = false) List<String> fields) {
return "";
}
2. 参数校验
2.1 引入 Hibernate Validator 包
<dependency>
<groupId>org.hibernate.validator</groupId>
<artifactId>hibernate-validator</artifactId>
</dependency>
<!-- Hibernate是5.2之前的版本还需要hibernate-entitymanager -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
</dependency>
非空校验通常会自动启用，因为 Spring Boot 自动配置会扫描并注册 javax.validation.Validator 的实现
import javax.validation.Valid; 来自
2.2 示例
- 在实体类的属性上添加非空注解
@Data
public class UserDTO {
@NotBlank(message = "name不能为空")
private String name;
@NotNull(message = "age不能为null")
private Integer age;
}
- 在请求参数前加上 @Valid 注解进行校验
import javax.validation.Valid;
@RestController
@RequestMapping("/web")
public class ConcreteController {
@RequestMapping("/greeting")
public UserDTO greeting(UserDTO userDTO) {
greetService.greeting(new UserDTO("Tinyspot", 20), "local");
return new UserDTO("bob", 22);
}
@RequestMapping("/greeting2")
public UserDTO greeting2(@Valid @RequestBody UserDTO userDTO) {
return userDTO;
}
}
@Valid 是 Spring 支持的注解，它会触发对带有校验注解的对象进行验证
@NotNull 表示字段不能为 null
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>Index</title>
<script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
</head>
<body>
<div id="search-param-bar">
姓名: <input id="name" placeholder="请输入"/><br>
年龄: <input id="age" value="20" placeholder="年龄"/><br>
<button id="do-search">查询</button>
</div>
<script type="text/javascript">
$(() => {
// 在 DOM 文档加载完成后执行的代码
$("#do-search").on("click", function () {
doSearch();
});
});
function doSearch() {
var name = $("#name").val();
var age = $("#age").val();
$.ajax({
type: "POST",
url: "/web/greeting",
data: {
name: name,
age: age
},
async: true,
dataType: "json",
success: function (data) {
console.log(data)
}
});
// 参数转JSON
params = {
name: name,
age: age
};
$.ajax({
type: "POST",
url: "/web/greeting2",
data: JSON.stringify(params),
async: true,
dataType: "json",
contentType: "application/json",
success: function (data) {
console.log(data)
}
});
}
</script>
</body>
</html>
2.3 参数校验异常捕获
Resolved [org.springframework.web.bind.MethodArgumentNotValidException: Validation failed for argument [0] in public com.example.concrete.common.domain.UserDTO com.example.concrete.starter.controller.ConcreteController.greeting2(com.example.concrete.common.domain.UserDTO):
[Field error in object 'userDTO' on field 'name': rejected value []; codes [NotBlank.userDTO.name,NotBlank.name,NotBlank.java.lang.String,NotBlank];
arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [userDTO.name,name]; arguments []; default message [name]]; default message [name不能为空]] ]
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