Question

我正在研究Spring Boot应用程序并开发Spring Rest（PATCH）服务。

我遇到一种情况，我需要将HashMap中PATCH请求中从前端收到的数据映射到Java POJO类。

我需要在POJO类中映射的属性出现在Hashmap的键中。我们需要遍历地图并将地图中键的值与POJO类属性相关联。

做到这一点的最佳方法是什么？我知道有一种非常巧妙的方法，我可以手动检查映射中的每个键，并将对应的值关联到POJO类中的适当的setter上。但是，如果POJO类中的属性数量很多，这将非常麻烦。

有没有一种有效的方法来实现这一目标？

代码段

@CrossOrigin
    @RequestMapping(value="/{id}", method = RequestMethod.PATCH)
    public Project editProject(@RequestBody Map<String, String> project, @PathVariable("id") String id) throws Exception {

        logger.info("Inside editProject() API ");

        if(project == null) {
            return null;
        }

        for(String key: project.keySet()) {
            logger.info("Keys passed for update ==> Key(" + key + "): Value(" + project.get(key) + ")");
        }

        Project projectRec = null;

        try {

            logger.info("updateProject() :: Before save :: ");

            projectRec = projectService.updateProjectInfo(project, id);

            logger.info("updateProject() :: After save :: Saved successfully ::: ", projectRec.toString());
        }
        catch (Exception ex) {
            ex.printStackTrace();
            throw ex;
        }

        logger.info("Leaving createProject() API");

        return projectRec;
    }

public Project updateProjectInfo(Map<String, String> projectRec, String id) {

        logger.info("Inside updateProjectInfo() API in ProjectServiceImpl");

        Project dbRec = projectRepository.findOne(id);

        setAttributesfromMaptoDBRec(projectRec, dbRec);

        Project updatedProjectRec = null;

        logger.info(" Leaving updateProjectInfo() API in ProjectServiceImpl");

        return updatedProjectRec;
    }

private void setAttributesfromMaptoDBRec(Map<String, String> updatedProjectRecMap, Project updatedProjectRec) {

        logger.info(" Inside setAttributesfromMaptoDBRec() API in ProjectServiceImpl");

        Set<String> nonUpdateableAttributes = ProjectServiceImpl.nonUpdateableKeys.get(ProjectServiceImpl.nonUpdateable);

        if(updatedProjectRecMap == null) {
            logger.warn(" Input Map to service is null in ProjectServiceImpl ===> " + (updatedProjectRecMap == null));
            return;
        }

        for(String key: updatedProjectRecMap.keySet()) {

            logger.info(" Project property ===>  " + key);

            logger.info(" nonUpdateableAttributes contains key  ===> " + nonUpdateableAttributes.contains(key));

            if(!nonUpdateableAttributes.contains(key)) {
                try {
                    System.out.println("Field name: " + updatedProjectRec.getClass().getField(key));
                    System.out.println("HOW TO AUTOMATICALLY SET THE ATTRIBUTE TO THE POJO CLASS BASED ON THE KEY ??");
                } catch(Exception ex) {
                    ex.printStackTrace();
                }

            }
        }


    }

Answer 1

很早以前，我就使用Jackson数据绑定API做过类似的事情。不确定，但这可能会有所帮助：

import java.util.Map;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;

public class ObjectMarshalUtility {

    public static <T> Map marshalObject(T obj){
        ObjectMapper oMapper = new ObjectMapper();
        oMapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
        return oMapper.convertValue(obj, Map.class);
    }

    public static <T> T unMarshalObject(Class<T> classType, Map<String, Object> map){
        ObjectMapper oMapper = new ObjectMapper();
        oMapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
        return oMapper.convertValue(map, classType);
    }
}

用于将DTO转换为MAP：

Map<String,Object> searchInputMap=ObjectMarshalUtility.marshalObject(searchInputDTO);

用于将地图转换为DTO：

SearchInputDTO searchInputDTO=ObjectMarshalUtility.unMarshalObject(searchInputMap);

如何将属性从Java Map自动映射到POJO类属性

1 个答案: