更换数据库，应用程序跨平台 两个问题的解决——JDBC
JDBC——JDBC标准API（java.sql，javax.sql），JDBC驱动程序
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要取得数据库联机： 注册Driver操作对象 取得Connection操作对象 关闭Connection操作对象
Class.forName(“com.mysql.jdbc.Driver”);
Connection conn = DriverManager.getConnection(jdbcUrl,username,password);
======================================================= Statement stmt = conn.createStatement();
int i = stmt.executeUpdate(“INSERT INTO t_message VALUES(1,’justin’,”+“‘justin@mail.com’,’message…’)”);
ResultSet result = stmt.executeQuery(“SELECT * FROM t_message”); result.getString(“name”),result.getInt(“id”)
stmt.execute(sql) ResultSet rs = stmt.getResultSet(); int updated = stmt.getUpdateCount();
