java便捷-封裝dao實作工具類

package lss.util;

import java.lang.reflect.Field;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.ResultSetMetaData;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class C3p0Util {

public static Connection conn=null;
  public static DataSource dSource=null;
 //獲得資料源
  static{
	  dSource=new ComboPooledDataSource("datas");
  }
/**
 *@return conn;
 */
  //獲得連接配接對象
    	public static Connection getConnection(){
    		try{
    			conn=dSource.getConnection();
    		}catch (Exception e) {
				e.printStackTrace();
			System.err.println("連接配接資料庫失敗");
    		}
    		return conn;
    	}
//關閉連接配接資料庫
       public static void closeDB(ResultSet rSet,PreparedStatement psmt,Connection conn){
    	   try{//依次關閉rSet\pSmt\conn
    		   if(rSet!=null){
    			   rSet.close();
    		   }
    		   if(psmt!=null){
    			   psmt.close();
    		   }	
    		   if(conn!=null){
    			   conn.close();
    		   }
    	   }catch (Exception e) {
		e.printStackTrace();
		System.err.println("關閉資料庫失敗");
		}
       }
      //查詢操作 
   	public static ResultSet dbQuery(Connection conn ,String sql,Object ...obj){
		ResultSet rs=null;
		PreparedStatement pstmt=null;
		try{
		    pstmt=conn.prepareStatement(sql);
		    for(int i=0;i<obj.length;i++){
		    	pstmt.setObject(i+1, obj[i]);
		    }
		    rs=pstmt.executeQuery();
		}catch(Exception e){
			e.printStackTrace();
		}
		return rs;
	}

   	
  //更新操作
	public static int dbUpdate(Connection conn,String sql,Object...obj){
		PreparedStatement pstmt=null;
		
		int k=0;
		try{
			//把SQL語句發送給資料庫
			pstmt=conn.prepareStatement(sql);
			//給占位符設定值
			for(int i=0;i<obj.length;i++){
				pstmt.setObject(i+1, obj[i]);
			}
			k=pstmt.executeUpdate();
		}catch(Exception e){
			e.printStackTrace();
		}
     		closeDB(null, pstmt, conn);
		return k;
	}   
	
	
	/**************增加資料集合通用方法**********************/
           

//轉換大小寫

public static String toUpperOne(String str){

str= str.substring(0,1).toUpperCase()+str.substring(1);

return str;

}

//實作通用底層查詢注入java bean 方法
	//查詢簡便方法
	 public static <T> T queryGS(Class<T> clazz,String sql,Object ...obj){
		  List<T> result = getForList(clazz, sql, obj);
			if(result.size() > 0){
				return result.get(0);
			}	
			return null;
	  }
		  
	  public static<T> List<T> getForList(Class<T> clazz,String sql,Object ...obj){
		  List<T> list=new ArrayList<>();
		  Connection conn=null;
		  PreparedStatement prstmt=null;
		  ResultSet rs=null;
		  try {
			conn=getConnection();
			prstmt=conn.prepareStatement(sql);
			for(int i=0;i<obj.length;i++){
				prstmt.setObject(i+1, obj[i]);
			}
			rs=prstmt.executeQuery();
			List<Map<String,Object>> values=new ArrayList<>();
			ResultSetMetaData rsmd=rs.getMetaData();
			Map<String,Object> map=null;
			while(rs.next()){
				map=new HashMap<>();
				for(int i=0;i<rsmd.getColumnCount();i++){
					String columnLabel = rsmd.getColumnLabel(i+1);
					Object value=rs.getObject(i+1);
					map.put(columnLabel, value);
				}
				values.add(map);
			}
			T bean=null;
			if(values.size()>0){
				for(Map<String,Object> m:values){
					bean=clazz.newInstance();
					for(Map.Entry<String , Object> entry:m.entrySet()){
						String propertyName=entry.getKey().toLowerCase();
						if("r".equals(propertyName))continue;
						Object value=entry.getValue();
						Field field =clazz.getDeclaredField(propertyName);  
						field.setAccessible(true);
						field.set(bean, value);
					}
					list.add(bean);
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally{
			closeDB(rs,prstmt , conn);
		}	  
		  return list;
	  }
	  
	 
	  public static<E> E getForValue(String sql, Object... args) {
		  List<E> list= getValueList(sql,args);
		  if(list.size()>0)
		      return list.get(0);
		  return null;
		}

	  
	   @SuppressWarnings("unchecked")
	public static<E> List<E> getValueList(String sql, Object... args) {
		   Connection connection = null;
			PreparedStatement preparedStatement = null;
			ResultSet resultSet = null;
			List<E> list =new ArrayList<E>();
			try {
				connection = getConnection();
				preparedStatement = connection.prepareStatement(sql);
				for (int i = 0; i < args.length; i++) {
					preparedStatement.setObject(i + 1, args[i]);
				}
				resultSet = preparedStatement.executeQuery();				
				while(resultSet.next()){
					list.add((E)resultSet.getObject(1));
				}
			} catch(Exception ex){
				ex.printStackTrace();
			} finally{
				closeDB(resultSet, preparedStatement, connection);
			}	
			return list;
	   }
	   
	   public static <T> int update(T bean){
		   @SuppressWarnings("unchecked")
		Class<T> clazz = (Class<T>) bean.getClass();
		   int k=0;
		   StringBuffer sql=new StringBuffer();
		   sql.append("update "+clazz.getName()+" set ");
		   try{
		   Field[] fields = clazz.getDeclaredFields();
		   for(int i=0;i<fields.length;i++){
			   String name= fields[i].getName();
			   Object value=fields[i].get(name);
			   sql.append(name+"="+value+" ");
			   System.out.println(name+":"+value);
		   }
		   }catch(Exception e){
			   e.printStackTrace();
		   }finally {
				closeDB(null, null, conn);
	       	}
		   return k;
	   }
           

}

作者技術部落格:

https://lsson.xyz/myblogs

如需聯系歡迎加q群：

855473670

481557406