pom.xml引入依賴 
<!--引數校驗-->
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-validation</artifactId>
    </dependency>
controller
        如果實體需要兩個實體類接受引數一個為user一個為role實體，可以巢狀驗證   

@RestController
public class
 
 HelloController {
    @RequestMapping("/hello")
    public Object index(@Valid Role role, BindingResult bindingResult){
        List<ObjectError> error=null;
     //返回boolean 是為了驗證@Validated後面bean 裡是否有不符合註解條件的錯誤資訊
     if(bindingResult.hasErrors()){
         //獲得所有錯誤資訊返回list集合
         error=bindingResult.getAllErrors();
         
 
for (ObjectError o:error) {
             //獲得不符合要求的message
             return o.getDefaultMessage();
         }

     }
        return null;
    }
實體
    User
import javax.validation.constraints.NotEmpty;
import javax.validation.constraints.NotNull;
import java.util.List;

public class User {
    private
 
 Integer id;
    @NotEmpty(message = "name不能為空")
    private String username;
    @NotEmpty(message = "password不能為空")
    private String password;
    //@NotNull   Integer型別用notnull註解


    private List<SysRole> roles;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public List<SysRole> getRoles() {
        return roles;
    }

    public void setRoles(List<SysRole> roles) {
        this.roles = roles;
    }
}
Role
import javax.validation.Valid;
import javax.validation.constraints.NotEmpty;
import javax.validation.constraints.NotNull;



public class SysRole {
    private Integer id;
   @NotEmpty(message = "name不能為空")
    private String name;
   @Valid
   private User user；
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }