Map与实体类相互转换

方式一：使用JSON方式转换

1. 在中引入依赖包

	<dependency>
	    <groupId></groupId>
	    <artifactId>fastjson</artifactId>
	    <version>1.2.54</version>
	</dependency>

2. 类型转换

package com.wb.workbook.util;

import com.alibaba.fastjson.JSON;
import lombok.Data;

import java.util.HashMap;
import java.util.Map;

public class ConvertEntityUtils {

    public static void main(String[] args) {

        Map<String, Object> dataMap = new HashMap<>(16);
        dataMap.put("id", "123");
        dataMap.put("name", "zhangsan");
        dataMap.put("age", 20);

        // map转换实体类
        UserEntity userEntity = JSON.parseObject(JSON.toJSONString(dataMap), UserEntity.class);
        System.out.println(JSON.toJSONString(userEntity));
		//输出结果：{"age":20,"id":"123","name":"zhangsan"}

        // 实体类转换map
        Map map = JSON.parseObject(JSON.toJSONString(userEntity), Map.class);
        System.out.println(JSON.toJSONString(map));
        //数据结果：{"name":"zhangsan","id":"123","age":20}
    }

    @Data
    private static class UserEntity {

        private String id;

        private String name;

        private Integer age;
    }

}

方式二：使用反射方式转换

1. 执行转换方法

public static void main(String[] args) {

	Map<String, Object> dataMap = new HashMap<>(16);
	dataMap.put("id", "123");
	dataMap.put("name", "zhangsan");
	dataMap.put("age", 20);
	
	// map转换实体类
	UserEntity userEntity = mapToEntity(dataMap, UserEntity.class);
	System.out.println(JSON.toJSONString(userEntity));
	// 输出结果：{"age":20,"id":"123","name":"zhangsan"}
	
	// 实体类转换map
	Map<String, Object> map = entityToMap(userEntity);
	System.out.println(JSON.toJSONString(map));
	// 输出结果：{"name":"zhangsan","id":"123","age":20}
}

2. UserEntity实体类

@Data
private static class UserEntity {

    private String id;

    private String name;

    private Integer age;
}

3. 使用反射方式进行转换

package com.wb.workbook.util;

import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Map;

/**
 * 实体类转换工具类.
 */
public class ConvertEntityUtils {

    /**
     * map转换实体类.
     *
     * @param dataMap 数据map集合.
     * @param clazz   指定实体类.
     * @param <T>     范型.
     * @return 实体类.
     */
    public static <T> T mapToEntity(Map<String, Object> dataMap, Class<T> clazz) {

        try {
            T obj = clazz.newInstance();

            for (Map.Entry<String, Object> entityKey : dataMap.entrySet()) {

                String fieldName = entityKey.getKey();

                Field field = clazz.getDeclaredField(fieldName);
                if (!field.isAccessible()) {
                    field.setAccessible(true);
                }

                field.set(obj, entityKey.getValue());
            }
            return obj;
        } catch (Exception e) {
            e.printStackTrace();
            throw new RuntimeException("mapToEntity is error!");
        }

    }

    /**
     * 实体类转换map.
     *
     * @param entity 实体类.
     * @param <T>    范型.
     * @return map.
     */
    public static <T> Map<String, Object> entityToMap(T entity) {

        try {
            Map<String, Object> resultMap = new HashMap<>(16);

            // 获取对象的类
            Class<?> clazz = entity.getClass();

            // 获取类中的所有字段
            Field[] fields = clazz.getDeclaredFields();

            // 循环遍历，将字段名与值存入Map
            for (Field field : fields) {

                // 设置字段可访问（非public字段需要设置访问权限）
                field.setAccessible(true);

                // 获取字段名称
                String fieldName = field.getName();

                // 获取字段值
                Object fieldValue = field.get(entity);

                // 将字段名与字段值存入Map
                resultMap.put(fieldName, fieldValue);
            }

            return resultMap;
        } catch (Exception e) {
            e.printStackTrace();
            throw new RuntimeException("entityToMap is error!");
        }
    }
    
}

方式三：使用stream进行实体类转换map

1. 执行转换方法

 public static void main(String[] args) {

	UserEntity userEntity = new UserEntity();
	userEntity.setId("123");
	userEntity.setName("zhangsan");
	userEntity.setAge(20);
	
	// 实体类转换map
	Map<String, Object> map = convertEntityToMap(userEntity);
	System.out.println(JSON.toJSONString(map));
	// 输出结果：{"name":"zhangsan","id":"123","age":20}
}

2. UserEntity实体类

@Data
private static class UserEntity {

    private String id;

    private String name;

    private Integer age;
}

3. 使用stream进行转换

 public static <T> Map<String, Object> convertEntityToMap(T entity) {
	// 使用Stream的简洁方式将实体类属性转换为Map
	Map<String, Object> map = Arrays.stream(entity.getClass().getDeclaredFields())
	        .peek(field -> field.setAccessible(true))
	        .collect(Collectors.toMap(Field::getName, field -> {
	            try {
	                return field.get(entity);
	            } catch (IllegalAccessException e) {
	                throw new RuntimeException("convertEntityToMap is error!");
	            }
	        }));
	return map;
}