写一段java版复杂JSON Map转类对象代码https://www.94rg.com/article/1795#menu_0
import java.util.Map; import org.springframework.cglib.beans.BeanMap; public static <T> T mapToBean(Map<String, Object> map, Class<T> clazz) { if (map == null || clazz == null) { return null; } T t = clazz.newInstance(); BeanMap beanMap = BeanMap.create(t); beanMap.putAll(map); return t; } import java.util.Map; import net.sf.json.JSONObject; public static <T> T map2Obj(Map<String, Object> map, Class<T> clazz) { JSONObject jsonObject = JSONObject.fromObject(map); return JSONObject.toJavaObject(jsonObject, clazz); }
https://aixcoder.com/nl2code/
orika vs mapstruct技术
import java.lang.reflect.Field; import java.util.HashMap; import java.util.Map; public class objectToMap { public static Map<String, Object> objectToMap(Object obj) { Map<String, Object> map = new HashMap<>(); if (obj == null) { return map; } Class clazz = obj.getClass(); Field[] fields = clazz.getDeclaredFields(); try { for (Field field : fields) { field.setAccessible(true); map.put(field.getName(), field.get(obj)); } } catch ( Exception e) { e.printStackTrace(); } return map; } }
https://www.94rg.com/article/1795#menu_0
1、各大对象映射框架性能对比
| 工具 | 实现方式 | 缺点 | 说明 |
|---|---|---|---|
| mapstruct | getter/setter方法 | 需要了解注解和配置项语法 | JSR269注解处理器在编译期自动生成Java Bean转换代码，支持可配置化，扩展性强 |
| orika | 动态生成字节码 | 首次调用耗时较久,性能适中 | 采用javassist类库生成Bean映射的字节码，之后直接加载执行生成的字节码文件 |
| Spring BeanUtils | 反射机制 | 不支持名称相同但类型不同的属性转换 | |
| Apache BeanUtils | 反射机制 | 需要处理编译期异常，性能最差 | |
| dozer | 反射机制 | 性能差 | 使用reflect包下Field类的set(Object obj, Object value)方法进行属性赋值 |
| BeanCopier | 反射机制 | \1. BeanCopier只拷贝名称和类型都相同的属性。即便基本类型与其对应的包装类型也不能相互转换; | 使用ASM的MethodVisitor直接编写各属性的get/set方法 |
就性能而言：mapstruct性能无疑是是最高的，接下来依次是Spring BeanUtils>orika>BeanCopier>dozer>apache BeanUtils
2、MapStruct的使用
2.1、引入pom
<dependency>
<groupId>org.mapstruct</groupId>
<artifactId>mapstruct</artifactId>
<version>1.3.0.Final</version>
<scope>provided</scope>
</dependency>
2.2 、单个bean映射
import org.mapstruct.Mapper;
import org.mapstruct.Mapping;
@Mapper(componentModel = "spring")
public interface OrderConvert {
@Mapping(source = "id", target = "orderId")
@Mapping(source = "createTime", target = "orderTime", dateFormat = "yyyy-MM-dd HH:mm:ss")
OrderDTO from(Order order);
}
测试代码
@Test
public void test() {
Order order = Order.builder()
.id(123L)
.buyerPhone("13707318123")
.buyerAddress("中电软件园")
.amount(10000L)
.payStatus(1)
.createTime(LocalDateTime.now())
.build();
OrderConvert orderConvert = Mappers.getMapper(OrderConvert.class);
OrderDTO orderDTO = orderConvert.from(order);
System.out.println("order: " + order);
System.out.println("orderDTO: " + orderDTO);
}
2.3、多个bean的映射
@Mapper(componentModel = "spring")
public interface GoodInfoConvert {
/** Long => String 隐式类型转换 */
@Mapping(source = "good.id", target = "goodId")
/** 属性名不同， */
@Mapping(source = "type.name", target = "typeName")
/** 属性名不同 */
@Mapping(source = "good.title", target = "goodName")
/** 属性名不同 */
@Mapping(source = "good.price", target = "goodPrice")
GoodInfoDTO from(GoodInfo good, GoodType type);
}
2.4、参数的含义映射
import org.mapstruct.Mapper;
import org.mapstruct.Mapping;
import java.time.LocalDate;
import java.time.LocalDateTime;
@Mapper(imports = {CustomMapping.class})
public interface StudentConvert {
@Mapping(source = "id", target = "studentId")
@Mapping(source = "name", target = "studentName")
@Mapping(source = "age", target = "age")
@Mapping(target = "ageLevel", expression = "java(CustomMapping.ageLevel(student.getAge()))")
@Mapping(target = "sexName", expression = "java(CustomMapping.sexName(student.getSex()))")
@Mapping(source = "admissionTime", target = "admissionDate", dateFormat = "yyyy-MM-dd")
StudentDTO from(Student student);
default LocalDate map(LocalDateTime time) {
return time.toLocalDate();
}
}
自定义的映射类
public class CustomMapping {
static final String[] SEX = {"女", "男", "未知"};
public static String sexName(Integer sex) {
if (sex < 0 && sex > 2){
throw new IllegalArgumentException("invalid sex: " + sex);
}
return SEX[sex];
}
public static String ageLevel(Integer age) {
if (age < 18) {
return "少年";
} else if (age >= 18 && age < 30) {
return "青年";
} else if (age >= 30 && age < 60) {
return "中年";
} else {
return "老年";
}
}
}
3、orika的使用
3.1 引入pom
<dependency>
<groupId>ma.glasnost.orika</groupId>
<artifactId>orika-core</artifactId>
<version>1.5.2</version>
</dependency>
3.2、初始化实例
package tech.chenxing.deploy.configuration;
import ma.glasnost.orika.MapperFactory;
import ma.glasnost.orika.impl.DefaultMapperFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class MapperConfig {
@Bean
public MapperFactory mapperFactory() {
return new DefaultMapperFactory.Builder().build();
}
}
3.3、配置映射对象
定义转换器
public class FlowDocDOConverter extends CustomMapper<FlowDoc, FlowDocBean> {
@Autowired private DocInfoMapperExt docInfoMapperExt;
@Override
public void mapAtoB(FlowDoc flowDocDO, FlowDocBean flowDocBean, MappingContext context) {
if (StringUtils.isNotBlank(flowDocDO.getDocUuid())) {
DocInfo docInfoDO = docInfoMapperExt.getByUUID(flowDocDO.getDocUuid());
ValidationUtil.assertNull(
docInfoDO,
new BizFlowManagerException(
BizFlowManagerBaseResultCodeEnum.FLOW_NOT_EXISTS,
flowDocDO.getDocUuid()));
flowDocBean.setId(docInfoDO.getId());
flowDocBean.setFileId(docInfoDO.getFileId());
flowDocBean.setName(docInfoDO.getName());
flowDocBean.setDocPassword(docInfoDO.getDocPassword());
flowDocBean.setDocSource(docInfoDO.getDocSource());
flowDocBean.setEncryption(docInfoDO.getEncryption());
flowDocBean.setGmtCreate(flowDocDO.getGmtCreate());
flowDocBean.setGmtModified(flowDocDO.getGmtModified());
}
}
}
注入转换器
package tech.chenxing.deploy.configuration;
import ma.glasnost.orika.MapperFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import javax.annotation.PostConstruct;
@Component
public class MapperInit {
@Autowired private MapperFactory mapperFactory;
@Autowired private FlowDocDOConverter flowDocDOConverter;
@PostConstruct
public void init() {
// 注册文档映射方式
mapperFactory
.classMap(User.class, UserDTO.class)
.field("docUuid", "docId")
.byDefault() // 剩余的字段映射
.customize(flowDocDOConverter)
.register();
}
}
代码使用
public xxx queryuser() {
List<User> userList =
userMapperExt.queryUser();
List<UserDTO> userDTOList =
mapperFactory.getMapperFacade().mapAsList(userList, UserDTO.class);
QueryFlowDocResult queryFlowDocResult = new QueryFlowDocResult();
}
