关于Java中的dozer对象转换问题

2022-11-13 16:11:13 java 对象 转换

Java中的dozer对象转换

1、dozer介绍

Dozer是Java Bean到Java Bean映射器,它以递归方式将数据从一个对象复制到另一个对象。 dozer是用来对两个对象之间属性转换的工具,有了这个工具之后,我们将一个对象的所有属性值转给另一个对象时,就不需要再去写重复的调用set和get方法了。dozer其实是对我们熟知的beanutils的封装。

2、依赖坐标

<dependency>
    <groupId>com.GitHub.dozermapper</groupId>
    <artifactId>dozer-core</artifactId>
    <version>6.5.0</version>
</dependency>

为了简化使用方式,dozer还提供了starter,其Maven坐标为:

<dependency>
    <groupId>com.github.dozermapper</groupId>
    <artifactId>dozer-spring-boot-starter</artifactId>
    <version>6.5.0</version>
</dependency>

3、创建测试工厂【dozer_demo】

3.1、引入对应的依赖

<?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 http://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>2.2.2.RELEASE</version>
        <relativePath/>
    </parent>
    <groupId>org.example</groupId>
    <artifactId>dozer_demo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>com.github.dozermapper</groupId>
            <artifactId>dozer-spring-boot-starter</artifactId>
            <version>6.5.0</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
    </dependencies>

</project>

3.2、创建UserDTO和UserEntity

dto:用户后端前端之间的数据交互或后端之间的数据交互
entity:对应的是数据库列字段属性

package com.zcl.dto;

import lombok.Data;


@Data
public class UserDTO {
    private String userId;
    private String userName;
    private int userAge;
    private String address;
    private String birthday;
}

实际项目中的属性命名可能是一致的,而下面的使用属性故意设置为个别属性不一致,测试属性名不一致的时候如何进行对象的转换

package com.zcl.UserEntity;

import lombok.Data;

import java.util.Date;


@Data
public class UserEntity {
    private String id;
    private String name;
    private int age;
    private String address;
    private Date birthday;
}

3.3、在resources/dozer/目录下创建dozer的全局配置文件global.dozer.xml

文件名称可以自定义,该配置文件的主要作用是配置全局的一个日期时间格式统一

<?xml version="1.0" encoding="UTF-8"?>
<mappings xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xmlns="http://dozermapper.github.io/schema/bean-mapping"
          xsi:schemaLocation="http://dozermapper.github.io/schema/bean-mapping 
                              http://dozermapper.github.io/schema/bean-mapping.xsd">
    <!--
    全局配置:
    <date-fORMat>表示日期格式
     -->
    <configuration>
        <date-format>yyyy-MM-dd</date-format>
    </configuration>
</mappings>

3.4、在resources/dozer/目录下创建dozer的映射文件biz.dozer.xml

该映射文件的主要作用是:将两个JavaBean不同的属性字段进行描述(谁对应谁)的映射关系
文件名称可以自定义
date-format="yyyy-MM-dd"是上一个配置文件所定义的全局格式
下面的配置文件中通过定义配置文件的全路径名称来指定,如
<class-a>com.itheima.entity.UserEntity</class-a>
通过field来指定两个对象之间的映射关系

<?xml version="1.0" encoding="UTF-8"?>
<mappings xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xmlns="http://dozermapper.github.io/schema/bean-mapping"
          xsi:schemaLocation="http://dozermapper.github.io/schema/bean-mapping
                             http://dozermapper.github.io/schema/bean-mapping.xsd">
    <!--描述两个类中属性的对应关系,对于两个类中同名的属性可以不映射-->
    <mapping date-format="yyyy-MM-dd">
        <class-a>com.zcl.entity.UserEntity</class-a>
        <class-b>com.zcl.dto.UserDTO</class-b>
        <field>
            <a>id</a>
            <b>userId</b>
        </field>
        <field>
            <a>name</a>
            <b>userName</b>
        </field>
        <field>
            <a>age</a>
            <b>userAge</b>
        </field>
    </mapping>
    <!--
    可以使用map-id指定映射的标识,在程序中通过此标识来确定使用当前这个映射关系
    -->
    <mapping date-format="yyyy-MM-dd" map-id="user">
        <class-a>com.zcl.entity.UserEntity</class-a>
        <class-b>com.zcl.dto.UserDTO</class-b>
        <field>
            <a>id</a>
            <b>userId</b>
        </field>
        <field>
            <a>name</a>
            <b>userName</b>
        </field>
        <field>
            <a>age</a>
            <b>userAge</b>
        </field>
    </mapping>
</mappings>

3.5、编写application.yml文件

如果不在配置文件中指定的化,上面编写的两个映射关系配置文件都不会生效

dozer:
  mappingFiles:
    - classpath:dozer/global.dozer.xml
    - classpath:dozer/biz.dozer.xml

3.6、编写项目启动类

package com.zcl;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;


@SpringBootApplication
public class DozerApp {
    public static void main(String[] args) {
        SpringApplication.run(DozerApp.class, args);
    }
}

3.7、编写单元测试

package com.zcl.test;

import com.github.dozermapper.core.Mapper;
import com.zcl.DozerApp;
import com.zcl.dto.UserDTO;
import com.zcl.entity.UserEntity;
import org.junit.jupiter.api.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;


@RunWith(SpringRunner.class)
@SpringBootTest(classes = DozerApp.class)
public class DozerTest {
    
    @Autowired
    private Mapper mapper;
    @Test
    public void testDozer1(){
        UserDTO userDTO = new UserDTO();
        userDTO.setUserId("100");
        userDTO.setUserName("itcast");
        userDTO.setUserAge(20);
        userDTO.setAddress("bj");
        userDTO.setBirthday("2010-11-20");

        // 调用map方法进行复制(原数据,复制的目标对象)
        UserEntity user = mapper.map(userDTO, UserEntity.class);
        System.out.println(user);
        // UserEntity(id=100, name=itcast, age=20, address=bj, birthday=Sat Nov 20 00:00:00 CST 2010)
    }

    @Test
    public void testDozer2(){
        UserDTO userDTO = new UserDTO();
        userDTO.setUserId("100");
        userDTO.setUserName("itcast");
        userDTO.setUserAge(20);
        userDTO.setAddress("bj");
        userDTO.setBirthday("2010-11-20");

        UserEntity user = new UserEntity();
        user.setId("200");
        System.out.println(user);
        // UserEntity(id=200, name=null, age=0, address=null, birthday=null)
        mapper.map(userDTO,user);
        System.out.println(user);
        // UserEntity(id=100, name=itcast, age=20, address=bj, birthday=Sat Nov 20 00:00:00 CST 2010)
    }

    @Test
    public void testDozer3(){
        UserDTO userDTO = new UserDTO();
        userDTO.setUserId("100");
        userDTO.setUserName("itcast");
        userDTO.setUserAge(20);
        userDTO.setAddress("bj");

        UserEntity user = new UserEntity();
        System.out.println(user);
        // UserEntity(id=null, name=null, age=0, address=null, birthday=null)
        mapper.map(userDTO,user,"user");
        System.out.println(user);
        // UserEntity(id=100, name=itcast, age=20, address=bj, birthday=null)
    }
}

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