Java帶有實體類物件的通用查詢（基於反射機制）

摘要： listBy根據entity的引數查詢，get根據entity的型別和id查詢 /* * File: DataSource.java * Created By: [email protected] * Date: 2019-03-29 */ package...

listBy根據entity的引數查詢，get根據entity的型別和id查詢

/*
 * File: DataSource.java
 * Created By: [email protected]
 * Date: 2019-03-29
 */

package cn.okc.dev.rest.db;

import cn.okc.dev.rest.entity.Articles;
import cn.okc.dev.rest.entity.Projects;
import cn.okc.dev.rest.entity.User;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;


/**
 * @author fengtao.xue
 */
@Component
public class DataSource<T>{
static Logger logger = LoggerFactory.getLogger(DataSource.class);

private static ConcurrentMap<String, List> data = new ConcurrentHashMap<>();

/**
* 初次載入所有資料，放入快取
*/
static {
logger.info("******** first load data from native file......");
data.put(User.class.getName(), LoadData.getUser());
data.put(Articles.class.getName(), LoadData.getArticles());
data.put(Projects.class.getName(), LoadData.getProjects());
logger.info("******** load data from native file successfully");
}

/**
* listBy,列表資料
* @param entity
* @return
*/
public List<T> listBy(T entity){
logger.info("listBy:{} \n entity:{}", entity.getClass().getName(), entity);
List<T> result = new ArrayList<>();
try {
List<T> tList = data.get(entity.getClass().getName());
for (T t : tList){
int i = 0;
Field[] fields = entity.getClass().getDeclaredFields();
for (Field field : fields){
field.setAccessible(true);
Object srcField = field.get(entity);
Object dstField = field.get(t);
if (srcField != null && dstField != null && srcField != dstField){
i = 0;
break;
}
else {
i++;
}
}
if (i != 0){
result.add(t);
}
}
}catch (Exception e){
logger.error("Error: {}\n{}", e.getMessage(), e.getStackTrace());
}
return result;
}

/**
* get,跟進id獲取詳情
* @param entity
* @param id
* @return
*/
public T get(T entity,String id) {
logger.info("get:{},{}", entity.getClass().getName(),id);
try {
List<T> tList = data.get(entity.getClass().getName());
for (T t : tList){
Field field = entity.getClass().getDeclaredField("id");
field.setAccessible(true);
if (id.equals(field.get(t))){
return t;
}
}
}catch (Exception e){
logger.error("Error: {}\n{}", e.getMessage(), e.getStackTrace());
}
return null;
}

/**
* 重新整理快取
*/
public void refresh() {
logger.info("******** refresh all data");
data.clear();
data.put(User.class.getName(), LoadData.getUser());
data.put(Articles.class.getName(), LoadData.getArticles());
data.put(Projects.class.getName(), LoadData.getProjects());
}
}