Through JDBC, a comprehensive understanding of the role of reflection, the role of the interface

 Public voidTestdrivermanager ()throwsexception{//1. Prepare 4 strings to connect to the database. //the full class name of the drive.String Driverclass = "Com.mysql.jdbc.Driver"; //JDBC URLString Jdbcurl = "Jdbc:mysql:///test"; //UserString user = "root"; //PasswordString password = "1230"; //2. Load the database driver (the corresponding Driver implementation class has a registered-driven static code block.)Class.forName (Driverclass); //3. Get the database connection through the DriverManager getconnection () method.Connection Connection =drivermanager.getconnection (jdbcurl, user, password);             System.out.println (connection); }        /*** Driver is an interface: The database vendor must provide an interface for implementation. The database connection can be obtained from it.     * Database connections can be obtained through the Driver implementation class object. * * 1. Added MySQL driver * 1). Unzip Mysql-connector-java-5.1.7.zip * 2). Create a new Lib directory * 3 under the current project). Copy the Mysql-connector-java-5.1.7-bin.jar to the Lib directory * 4). Right-Build-path, add to BuildPath is added to the classpath. S *@throwsSQLException*/@Test Public voidTestdriver ()throwsSQLException {//1. Create an object of the Driver implementation classDriver Driver =NewCom.mysql.jdbc.Driver (); //2. Basic information about preparing a connection database: URL, user, passwordString url = "Jdbc:mysql://localhost:3306/test"; Properties Info=NewProperties (); Info.put ("User", "root"); Info.put ("Password", "1230"); //3. Call the Connect (URL, info) of the Driver interface to get the database connectionConnection Connection =driver.connect (URL, info);    System.out.println (connection); }        /*** Write a common method, without modifying the source program, can get the connection of any database * solution: The database-driven Driver implementation class of the full class name, URL, user, password into a * configuration file, by modifying      The configuration file is implemented in a way that is decoupled from the specific database. * @throwsException*/     PublicConnection getconnection ()throwsexception{String Driverclass=NULL; String Jdbcurl=NULL; String User=NULL; String Password=NULL; //read the Jdbc.properties file under the ClasspathInputStream in =getclass (). getClassLoader (). getResourceAsStream ("Jdbc.properties"); Properties Properties=NewProperties ();        Properties.load (in); Driverclass= Properties.getproperty ("Driver"); Jdbcurl= Properties.getproperty ("Jdbcurl"); User= Properties.getproperty ("User"); Password= Properties.getproperty ("Password"); //by reflecting common Driver objects.Driver Driver =(Driver) class.forname (Driverclass). newinstance (); Properties Info=NewProperties (); Info.put ("User", user); Info.put ("Password", password); //get the database connection through the Driver Connect method.Connection Connection =Driver.connect (Jdbcurl, info); returnconnection; } @Test Public voidTestgetconnection ()throwsexception{System.out.println (getconnection ()); }

Through JDBC, a comprehensive understanding of the role of reflection, the role of the interface