java

关注公众号 jb51net

关闭
首页 > 软件编程 > java > Spring BeanUtils忽略空值拷贝

Spring BeanUtils忽略空值拷贝的方法示例代码

作者:IT利刃出鞘

本文用示例介绍Spring(SpringBoot)如何使用BeanUtils拷贝对象属性忽略空置,忽略null值拷贝属性的用法,代码简单易懂,对大家的学习或工作具有一定的参考借鉴价值,需要的朋友参考下吧

简介

说明

本文用示例介绍Spring(SpringBoot)如何使用BeanUtils拷贝对象属性(忽略空值)。

BeanUtils类所在的包

有两个包都提供了BeanUtils类:

Spring的(推荐):org.springframework.beans.BeanUtilsApache的:org.apache.commons.beanutils.BeanUtils

忽略null值拷贝属性的用法

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

获取null属性名(工具类)

可以自己写一个工具类,用来获取对象里所有null的属性名字。

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);
    }
}

示例

本处为了全面,将以下几种情况都考虑进去:

工具类

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);
    }
}

Entity

基础Entity

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;
}

User

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;
}

Blog

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;
}

VO

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;
}

Controller

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";
    }
}

测试

访问:http://localhost:8080/test/

后端结果:

[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}}

结论

 其他文件

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.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>

其他网址

Spring BeanUtils忽略空值拷贝用法 - 掘金

到此这篇关于Spring BeanUtils忽略空值拷贝的方法示例代码的文章就介绍到这了,更多相关Spring BeanUtils忽略空值拷贝内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家!

您可能感兴趣的文章:
阅读全文