dbconn.java

vb+java实现的图书管理系统

package com.bean.util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Vector;
public class DbConn {
	@SuppressWarnings("unchecked")
	Vector dsVector=new Vector();
	int rowCount=0;
	int colCount=0;
	public String[] type=null;
	boolean flag=true;
	@SuppressWarnings("unchecked")
	public String[][] getData(String sql){
		query(sql);
		String dsString[][]=new String[rowCount][colCount];
		if(flag==true){
			dsString=null;
		}else{
			for (int i=0;i<rowCount;i++){
				Vector row=new Vector();
				row=(Vector)dsVector.get(i);
				for(int j=0;j<colCount;j++){
					dsString[i][j]=(String)row.get(j);
				}
			}
		}
		dsVector.clear();
		return dsString;
	}
	public static Connection getconn(){
		
		try {
			Class.forName("net.sourceforge.jtds.jdbc.Driver").newInstance();
		} catch (InstantiationException e) {
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
		String url="jdbc:jtds:sqlserver://localhost:1433/library"; 
		String user="sa";
		String psw="sa";
		Connection conn=null;
		try {
			conn=DriverManager.getConnection(url,user,psw);
		} catch (SQLException e) {
			e.printStackTrace();	
		}
		return conn;
	}
	public static void closeConn(Connection conn){
		try {
			conn.close();
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}
	public int update(String sql){
		Connection conn=DbConn.getconn();
		Statement stmt=null;
		int count=0;
		//System.out.println(sql);
		try {
			conn.setAutoCommit(false);
			stmt=conn.createStatement();
			//System.out.println(sql);
			count=stmt.executeUpdate(sql);
			conn.commit();
		} catch (SQLException e) {
			//System.out.print(e.getErrorCode());
			try{
				conn.rollback();
			}catch(SQLException e1){
				e1.printStackTrace();
			}
			e.printStackTrace();
		} catch (Exception e){
			e.printStackTrace();
		}finally{
			DbConn.closeConn(conn);
		}
		return count;
	}
	
	@SuppressWarnings("unchecked")
	public int query(String sql){
		Connection conn=DbConn.getconn();
		Statement stmt=null;
		ResultSet rs=null;
		rowCount=0;
		colCount=0;
		try {
			stmt=conn.createStatement();
			rs=stmt.executeQuery(sql);
			flag=true;
			while(rs.next()){
				flag=false;
				rowCount++;
				ResultSetMetaData rsmd= rs.getMetaData();
				Vector row=new Vector();
				colCount=rsmd.getColumnCount();
				for( int i= 0; i<colCount; i++){
					row.add(rs.getString(i+1));
				}
				dsVector.add(row);
			}
		} catch (SQLException e) {
			System.out.print(e.getErrorCode());
			e.printStackTrace();
		} catch (Exception e){
			e.printStackTrace();
		}finally{
			DbConn.closeConn(conn);
		}
		return rowCount;
	}
//		public static void main(String arg[]){
//			DbConn dbconn=new DbConn();
//			String username="whd";
//			String sql="select th_id,th_name from teachers";
//			//dbconn.query(sql);
//			String[][] dataSet= dbconn.getData(sql);
//			for (int i=0;i<dataSet.length;i++){
//				System.out.print(dataSet[i][0]+" "+dataSet[i][1]);
//			}
//			System.out.println();
//				
//			sql="select cour_id,cour_name from courses";
//			//dbconn.query(sql);
//			String[][] dataSet1= dbconn.getData(sql);
//			for (int i=0;i<dataSet1.length;i++){
//					System.out.print(dataSet1[i][0]+" "+dataSet1[i][1]);
//			}
//			System.out.println();
//		}
	
//	public static void main(String arg[]){
//		DbConn dbconn=new DbConn();		
//		String sql="select versionId,versionName,updateContent,updateP from softversion";
//		//dbconn.query(sql);
//		String[][] dataSet1= dbconn.getData(sql);
//		for (int i=0;i<dataSet1.length;i++){
//				System.out.print(dataSet1[i][0]+" "+dataSet1[i][1]);
//		}
//		System.out.println();
//	}
}