利用EntityManager封装的数据库查询模板

RestService.java

import java.math.BigInteger;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;

import org.hibernate.transform.Transformers;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.transaction.annotation.Propagation;

import com.alibaba.fastjson.JSON;

import JsonMapper;

@Service
@Transactional(propagation = Propagation.SUPPORTS, readOnly = true)
public class RestService {

    @PersistenceContext
    private EntityManager em;

    private static Logger log = LoggerFactory.getLogger(RestService.class);

    public String GetStringDemo(int id) {
        String sql = "select content from ** where id=" + id;
        return queryBySql2String(sql, "content");
    }
    
    public int getIntDefaultDemo(int id) {
        String sql = "select intColumn from ** where id=" + id;
        return queryBySql2IntDefault(sql, "intColumn");
    }
    
    public int getIntDemo(int id) {
        String sql = "select count(*) as cnt from ** where id=" + id;
        int count = queryBySql2Int(sql, "cnt");
        return count;
    }
    
    //此处的Object请替换成具体的类
    public Object getEntityDemo(int id) {
        String sql = "select * from ** where  id=" + id;        
        return queryBySql2Entity(sql, null, Object.class);
    }
    
    //此处的Object请替换成具体的类
    public List