问题描述

java 程序 与数据库连接问题

public class Test11 {
public static final String DRIVER = ""com.mysql.jdbc.Driver"";
public static final String URL = ""jdbc:mysql://localhost:3306/MySQL"";
public static final String USERNAME = ""root"";
public static final String PASSWORD = ""saber"";

Connection connection = null;PreparedStatement preparedStatement = null;ResultSet resultSet = null;public Connection getConnection() throws Exception {    Class.forName(DRIVER);    connection = DriverManager.getConnection(URLUSERNAMEPASSWORD);    System.out.println(""连接成功"");    return connection;}public ResultSet executeQuery(String sql) throws Exception {    connection = this.getConnection();    preparedStatement = connection.prepareStatement(sql);    resultSet = preparedStatement.executeQuery();    return resultSet;}public int executeUpdate(String sqlObject[] obj) throws Exception {    connection = this.getConnection();    preparedStatement = connection.prepareStatement(sql);    for(int i =0;i<obj.length;i++){        preparedStatement.setObject(i+1 obj[i]);    }    return preparedStatement.executeUpdate();}  //这一段代码能不能帮忙解释一下，这样写的作用。不是很理解~public void closeAll() throws Exception {    if(null != resultSet){        resultSet.close();    }    if(null != preparedStatement){        preparedStatement.close();    }    if(null != connection){        connection.close();    }}

新手，有点不懂这段代码我标的部分的意义，请逐句解释下，求指导。