一.dozer的作用

dozer是对BeanUtils的封装，是Java Bean到Java Bean的映射器，以递归方式将数据从一个对象复制到另一个对象，是用来对两个对象之间属性转换的工具。

二.dozer的使用

1.导入依赖

首先创建一个项目dozerDemo，引入dozer依赖：

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

为了使用方便，dozer还提供了starter：

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

2.创建用于转换的对象类

UserDTO.class

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

UserEntity.class

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

3.创建配置文件

在resource/dozer目录下创建全局配置文件global.dozer.xml：

<?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>
        <!--确定全局的日期格式为yyyy-MM-dd形式-->
        <date-format>yyyy-MM-dd HH:mm:ss</date-format>
    </configuration>
</mappings>

date-format表示全局的日期格式为yyyy-MM-dd形式，也就是日期类型转换的时候是转换为这种格式 创建dozer的映射文件：

<?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">
    <mapping date-format="yyyy-MM-dd HH:mm:ss">
        <class-a>cn.kz.dozerdemo.entity.UserEntity</class-a>
        <class-b>cn.kz.dozerdemo.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>cn.kz.dozerdemo.entity.UserEntity</class-a>
        <class-b>cn.kz.dozerdemo.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>

注意：如果两个对象类中的属性名相同，则不需要在映射文件使用标签进行映射，例如：

<mapping date-format="yyyy-MM-dd" map-id="same">
    <class-a>cn.kz.dozerdemo.entity.UserEntitySameName</class-a>
    <class-b>cn.kz.dozerdemo.dto.UserDTO</class-b>
</mapping>

在application.yml中：

server:
  port: 9100
dozer:
  mapping-files:
    - classpath:dozer/global.dozer.xml
    - classpath:dozer/biz.dozer.xml

4.编写测试单元

package cn.itcast.test;

import com.github.dozermapper.core.DozerBeanMapper;
import com.github.dozermapper.core.DozerBeanMapperBuilder;
import com.github.dozermapper.core.Mapper;
import com.github.dozermapper.core.metadata.MappingMetadata;
import com.itheima.DozerApp;
import com.itheima.dto.UserDTO;
import com.itheima.entity.UserEntity;
import org.junit.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");

        UserEntity user = mapper.map(userDTO, UserEntity.class);
        System.out.println(user);
    }

    @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);
        mapper.map(userDTO,user);
        System.out.println(user);
    }

    @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);
        mapper.map(userDTO,user,"user");
        System.out.println(user);
    }
}