JDBC

JDBC : Java DataBase Connectivity

两个部分

• Java自带API -> 跟具体数据库无关
• 各个数据库厂商开发的驱动，实际上JDBC API的不同实现 -> 跟具体数据库紧密耦合

常用API

1. DriverManager => public static Connection getConnection(url,user,passwd)
2. Connection => public Statement cretateStatement()
3. Statement => public boolean execute(sql) / public ResultSet executeQuery(sql)
4. ResultSet => while(rs.next()){ rs.getXXX(columnIndex); //…}

步骤

• 加载驱动 :Class.forName(“com.mysql.jdbc.Driver”);

• 获得链接 Connection conn=DriverManager.getConnection(CONN_URL, USER, PASSWORD);

• 创建statement对象

  • Statement

  • Statement sta=conn.createStatement()

  • PreparedStatement

  • PreparedStatement ps = conn.prepareStatement(sql);

  • eg:

    String sql = "select * from user where username=? and passwd=?"; PreparedStatement statement = conn.prepareStatement(sql);statement.setString(1, username);statement.setString(2, password);

• 执行sql

  • Statement

  • execute(sql)/executeQuery(sql)/executeUpdate(sql)

  • eg:

    ResultSet rs=sta.executeQuery("select *from book");

  • PreparedStatement

  • ps.executeQuery();

• 解析返回结果