一、案例，前台调用传入name、age、phone、address、password然后后台在插入数据库之前进行校验，判断name、address、password是否为null或者empty，phone格式是否正确，年龄是否大于18岁等等

1、创建User

package com.cn.dl;

import com.fasterxml.jackson.annotation.JsonIgnore;
import lombok.*;

import javax.validation.constraints.Min;
import javax.validation.constraints.NotBlank;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Pattern;
import java.io.Serializable;

/**
 *  这三个注解的区别
 *  @NotEmpty 用在集合类上面；不能为null，而且长度必须大于0
 *  @NotBlank 用在String上面；只能作用在String上，不能为null，而且调用trim()后，长度必须大于0
 *  @NotNull 用在基本类型上；不能为null，但可以为empty。
 * Created by Tiger on 2018/10/23.
 */
@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
public class User implements Serializable{

    private static final long serialVersionUID = 8474075197757594232L;

    @NotBlank(message = "the name cannot be empty or null")
    private String name;
    @NotNull(message = "the age cannot be empty or null")
    @Min(value = 18,message = "the age must be greater than or equal to 18")
    private Integer age;
    @NotBlank(message = "the phone cannot be empty or null")
    @Pattern(regexp = "^[1][3,4,5,7,8][0-9]{9}$",message = "the phone number format error")
    private String phone;
    @NotBlank(message = "the address cannot be empty or null")
    private String address;
    @JsonIgnore
    @NotBlank(message = "the password cannot be empty or null")
    private String password;
}

2、创建Response

package com.cn.dl.response;

import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import lombok.Getter;
import lombok.Setter;

import java.io.Serializable;

/**
 * 请求返回类
 * Created by Tiger on 2018/10/9.
 */
@Getter
@Setter
//// TODO: 2018/10/27 @JsonSerialize 如果返回的json中有null值，忽略 
@JsonSerialize(include= JsonSerialize.Inclusion.NON_NULL)
public class Response<T> implements Serializable {

    private static final long serialVersionUID = -4505655308965878999L;

    //请求成功返回码为：0000
    public static final String successCode = "0000";
    //请求失败返回码为：9999
    public static final String failedCode = "9999";
    //返回数据
    private T data;
    //返回码
    private String code;
    //返回描述
    private String msg;

    public Response(){
        this.code = successCode;
        this.msg = "请求成功";
    }

    public Response(String code, String msg){
        this();
        this.code = code;
        this.msg = msg;
    }
    public Response(String code, String msg, T data){
        this();
        this.code = code;
        this.msg = msg;
        this.data = data;
    }
    public Response(T data){
        this();
        this.data = data;
    }
}

3、创建UserController

package com.cn.dl.controller;

import com.cn.dl.User;
import com.cn.dl.response.Response;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.validation.Valid;

/**
 * Created by Tiger on 2018/10/26.
 */
@RestController
@RequestMapping("user")
public class UserController {

    @RequestMapping("insert")
    public Response insertUser(@Valid User user, BindingResult bindingResult){
        System.out.println(user.toString());
        if(bindingResult.hasErrors()){
            return new Response(Response.failedCode,bindingResult.getFieldError().getDefaultMessage());
        }
        //// TODO: 2018/10/27 保存数据等等
        return new Response(user);
    }
}

@Valid：用于校验User中的属性，BindingResult：返回校验失败的信息

二、测试

1、不输入age、name、phone、address、password

2、输入age小于18

3、输入name为空串时

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4、phone格式也是根据正则匹配、返回的User不包含password

5、如果去掉password上@JsonIgnore

{
    "data": {
        "name": "Tiger",
        "age": 18,
        "phone": "15769393859",
        "address": "beijing",
        "password": "123456"
    },
    "code": "0000",
    "msg": "请求成功"
}

三、分享一个postman小技巧：postman管理ip和port，这样就不需要我们每次都去输入ip和port了

• 打开Manage Environments

• 编辑Environment，输入Environment名字，输入key和Value，然后保存

• Environment选择刚才编辑的localhost，然后在输入{ 就会看到刚才编辑的key，其值就是对应的value，然后我们输入ip和port之外的url就ok了！