dbutil.java

一个由jsp+servlet+MySQL简单的新闻发布系统

package com.news.util;
import java.sql.*;
public class DButil {

	public static String Driver = "com.mysql.jdbc.Driver";
	public static String url = "jdbc:mysql://localhost:3306/news";
	public static String username="root";
	public static String password="admin";
	public static Statement stmt = null;
	public static Connection conn = null;
	public static PreparedStatement pstmt = null;
	
	public static void init(){
		try {
			Class.forName(Driver);
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
		
	}
	public static Connection getConnection() throws ClassNotFoundException{
		init();
		Connection conn = null;
		try {
			conn = DriverManager.getConnection(url, username, password);
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return conn;	
	}
	public static Statement getStatement(){
		Statement stmt = null;
		try {
			Class.forName(Driver);
			stmt = getConnection().createStatement();
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return stmt;
	}
	public static PreparedStatement getPreparedStatement(String sql){
		PreparedStatement pstmt = null;
		try {
			Class.forName(Driver);
			pstmt  = getConnection().prepareStatement(sql);
			//pstmt.executeUpdate();
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return pstmt;
	}
	public static void close(){
		if(conn!=null){
			try {
				conn.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}if(stmt!=null){
			try {
				stmt.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}if(pstmt!=null){
			try {
				pstmt.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}
	public static void main(String[] args) {
		Connection conn  = DButil.getConnection();
		int i = 1;

		//测试数据库连接
	    conn = DButil.getConnection();
		try {
			DatabaseMetaData dmd = null;
			dmd = conn.getMetaData();
			System.out.println("数据库名称：" + dmd.getDatabaseProductName());
			System.out.println("数据库版本：" + dmd.getDatabaseProductVersion());
			System.out.println("数据库用户名：" + dmd.getUserName());

			Statement stmt = conn.createStatement();
			ResultSet rs = stmt.executeQuery("select * from project.message");
			ResultSetMetaData rsmd = rs.getMetaData();
			System.out.println("有" + rsmd.getColumnCount() + "字段");
			System.out.println("第2个字段名称是：" + rsmd.getColumnName(2));
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}	
	}
}