JDBC连接常用数据库 基本的CURD

package com.itlwc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class DBConnection {
 private static Connection conn = null;
 private String user = "";
 private String password = "";
 private String className = "com.microsoft.jdbc.sqlserver.SQLServerDriver";
 private String url = "jdbc:microsoft:sqlserver://"
   + "localhost:1433;SelectMethod=Cursor;dataBaseName=lwc";

 private DBConnection() {
  try {
   Class.forName(this.className);
   conn = DriverManager.getConnection(url, user, password);
   System.out.println("连接数据库成功");
  } catch (ClassNotFoundException e) {
   System.out.println("连接数据库失败");
  } catch (SQLException e) {
   System.out.println("连接数据库失败");
  }
 }

 public static Connection getConn() {
  if (conn == null) {
   conn = (Connection) new DBConnection();
  }
  return conn;
 }

 // 关闭数据库
 public static void close(ResultSet rs, Statement state, Connection conn) {
  if (rs != null) {
   try {
    rs.close();
   } catch (SQLException e) {
    e.printStackTrace();
   }
   rs = null;
  }
  if (state != null) {
   try {
    state.close();
   } catch (SQLException e) {
    e.printStackTrace();
   }
   state = null;
  }
  if (conn != null) {
   try {
    conn.close();
   } catch (SQLException e) {
    e.printStackTrace();
   }
   conn = null;
  }
 }

 // 测试数据库连接是否成功
 public static void main(String[] args) {
  getConn();
 }
}