SQL Server 数据库连接类

package edu.qdgxy.db;

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

//1.加载驱动；2.建立连接3.创建Statement对象4.执行sql 5.关闭资源
public class DBBean {

	private String driverStr = "com.microsoft.sqlserver.jdbc.SQLServerDriver";

	private String connStr = "jdbc:sqlserver://localhost:1433;databaseName=PEM";
	//jdbc:sqlserver://localhost:1433;databaseName=数据库的名字
	private String username="sa";	
	private String password="sa";
	private Connection connection = null;
	private Statement stmt=null;
	private ResultSet rs = null;

	public DBBean() {
		try {
			Class.forName(driverStr);
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
	}
	
	private Connection getConnection(){
		try {
			connection=DriverManager.getConnection(connStr,username,password);
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return connection;
	}

	private Statement createStatement(){
		try {
			stmt=getConnection().createStatement();
		} catch (Exception e) {
			e.printStackTrace();
		}
		return stmt;
	}
	public ResultSet executeQuery(String sql) {
		try {
			rs = createStatement().executeQuery(sql);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return rs;
	}

	public int executeUpdate(String sql) {
		int result = 0;
		try {
			result = createStatement().executeUpdate(sql);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return result;
	}
	
	public void close(){
		try {
			if (rs != null)
				rs.close();
			if (stmt != null)
				stmt.close();
			if (connection != null)
				connection.close();
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

}