Spring BeanUtils忽略空值拷贝的方法示例代码

BeanUtils.copyProperties(Object source, Object target, String... ignoreProperties)

package com.example.util;

import org.springframework.beans.BeanWrapper;

import org.springframework.beans.BeanWrapperImpl;

import java.beans.PropertyDescriptor;

import java.util.HashSet;

import java.util.Set;

public class PropertyUtil {

     public static String[] getNullPropertyNames(Object source) {

         BeanWrapper src = new BeanWrapperImpl(source);

         PropertyDescriptor[] pds = src.getPropertyDescriptors();

         Set<String> emptyNames = new HashSet<>();

         for (PropertyDescriptor pd : pds) {

             //check if value of this property is null then add it to the collection

             Object srcValue = src.getPropertyValue(pd.getName());

             if (srcValue == null ){

                 emptyNames.add(pd.getName());

             }

         }

         String[] result = new String[emptyNames.size()];

         return emptyNames.toArray(result);

     }

}

package com.example.util;

import org.springframework.beans.BeanWrapper;

import org.springframework.beans.BeanWrapperImpl;

import java.beans.PropertyDescriptor;

import java.util.HashSet;

import java.util.Set;

public class PropertyUtil {

     public static String[] getNullPropertyNames(Object source) {

         BeanWrapper src = new BeanWrapperImpl(source);

         PropertyDescriptor[] pds = src.getPropertyDescriptors();

         Set<String> emptyNames = new HashSet<>();

         for (PropertyDescriptor pd : pds) {

             //check if value of this property is null then add it to the collection

             Object srcValue = src.getPropertyValue(pd.getName());

             if (srcValue == null ){

                 emptyNames.add(pd.getName());

             }

         }

         String[] result = new String[emptyNames.size()];

         return emptyNames.toArray(result);

     }

}

package com.example.entity;

import com.fasterxml.jackson.annotation.JsonFormat;

import lombok.Data;

import java.time.LocalDateTime;

@Data

public class BaseEntity {

     @JsonFormat (pattern = "yyyy-MM-dd HH:mm:ss" ,timezone= "GMT+8" )

     private LocalDateTime createTime;

     private LocalDateTime updateTime;

     private Long deletedFlag;

}

package com.example.entity;

import lombok.Data;

@Data

public class User {

     private Long id;

     private String userName;

     private String nickName;

     // 0:正常 1：被锁定

     private Integer status;

}

package com.example.entity;

import lombok.Data;

import lombok.EqualsAndHashCode;

@Data

@EqualsAndHashCode (callSuper = true )

public class Blog extends BaseEntity{

     private Long id;

     private String title;

     private String content;

     private User user;

}

package com.example.vo;

import com.example.entity.BaseEntity;

import com.example.entity.User;

import lombok.Data;

import lombok.EqualsAndHashCode;

@Data

@EqualsAndHashCode (callSuper = true )

public class BlogRequest extends BaseEntity {

     private Long id;

     private String title;

     private String content;

     private User user;

}

package com.example.controller;

import com.example.entity.Blog;

import com.example.entity.User;

import com.example.util.PropertyUtil;

import com.example.vo.BlogRequest;

import com.fasterxml.jackson.core.JsonProcessingException;

import com.fasterxml.jackson.databind.ObjectMapper;

import org.springframework.beans.BeanUtils;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.web.bind.annotation.GetMapping;

import org.springframework.web.bind.annotation.RestController;

import java.time.LocalDateTime;

import java.util.Arrays;

@RestController

public class HelloController {

     @Autowired

     private ObjectMapper objectMapper;

     @GetMapping ( "/test" )

     public String test() {

         BlogRequest blogRequest = new BlogRequest();

         blogRequest.setId(10L);

         blogRequest.setTitle( "Java实战" );

         // blogRequest.setContent("本文介绍获取null的字段名的方法");

         blogRequest.setUser( new User());

         blogRequest.setCreateTime(LocalDateTime.now());

         // blogRequest.setCreateTime(LocalDateTime.now());

         blogRequest.setDeletedFlag(0L);

         User user = new User();

         user.setId(15L);

         user.setUserName( "Tony" );

         // user.setNickName("Iron Man");

         // user.setStatus(1);

         String[] nullPropertyNames = PropertyUtil.getNullPropertyNames(blogRequest);

         System.out.println(Arrays.toString(nullPropertyNames));

         System.out.println( "------------------------------" );

         Blog blog = new Blog();

         BeanUtils.copyProperties(blogRequest, blog, nullPropertyNames);

         try {

             System.out.println(objectMapper.writeValueAsString(blog));

         } catch (JsonProcessingException e) {

             e.printStackTrace();

         }

         return "test success" ;

     }

}

[updateTime, content]

------------------------------

{"createTime":"2022-03-17 19:58:32","updateTime":null,"deletedFlag":0,"id":10,"title":"Java实战","content":null,"user":{"id":null,"userName":null,"nickName":null,"status":null}}

<? xml version = "1.0" encoding = "UTF-8" ?>

< project xmlns = "http://maven.apache.org/POM/4.0.0" xmlns:xsi = "http://HdhCmsTestw3.org/2001/XMLSchema-instance"

          xsi:schemaLocation = "http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd" >

     < modelVersion >4.0.0</ modelVersion >

     < parent >

         < groupId >org.springframework.boot</ groupId >

         < artifactId >spring-boot-starter-parent</ artifactId >

         < version >2.3.0.RELEASE</ version >

         < relativePath /> <!-- lookup parent from repository -->

     </ parent >

     < groupId >com.example</ groupId >

     < artifactId >demo_SpringBoot</ artifactId >

     < version >0.0.1-SNAPSHOT</ version >

     < name >demo_SpringBoot</ name >

     < description >Demo project for Spring Boot</ description >

     < properties >

         < java.version >1.8</ java.version >

     </ properties >

     < dependencies >

         < dependency >

             < groupId >org.springframework.boot</ groupId >

             < artifactId >spring-boot-starter-web</ artifactId >

         </ dependency >

         < dependency >

             < groupId >org.projectlombok</ groupId >

             < artifactId >lombok</ artifactId >

             < version >1.16.20</ version >

             < scope >provided</ scope >

         </ dependency >

     </ dependencies >

     < build >

         < plugins >

             < plugin >

                 < groupId >org.springframework.boot</ groupId >

                 < artifactId >spring-boot-maven-plugin</ artifactId >

                 < version >2.3.0.RELEASE</ version >

             </ plugin >

         </ plugins >

     </ build >

</ project >