JDBC Learning Note (4): A single-case toolkit

For ease of operation, connect the database, close the resource operation using the toolkit to complete:

1  PackageCom.xxyh.jdbc;2 Importjava.sql.Connection;3 ImportJava.sql.DriverManager;4 Importjava.sql.SQLException;5  Public classJdbcutilssingleton {6     Private FinalString url = "Jdbc:mysql://localhost:3306/jdbc";7     Private FinalString user = "root";8     Private FinalString password = "1234";9     Ten     Private StaticJdbcutilssingleton instance =NULL; One      A     PrivateJdbcutilssingleton () {} -      -     Static { the         Try { -Class.forName ("Com.mysql.jdbc.Driver"); -}Catch(ClassNotFoundException e) { -             Throw NewExceptionininitializererror (e); +         } -     } +      A     /*Lazy Type*/ at      Public Static synchronizedJdbcutilssingleton getinstance () { -         if(Instance = =NULL)  -Instance =NewJdbcutilssingleton (); -         returninstance; -     } -      in      PublicConnection getconnection ()throwsSQLException { -         returndrivermanager.getconnection (URL, user, password); to     } +}

Lazy-style improvements:

/*Lazy Type*/     Public Static synchronizedJdbcutilssingleton getinstance () {if(Instance = =NULL)             synchronized(Jdbcutilssingleton.class) {                if(Instance = =NULL) Instance=NewJdbcutilssingleton (); }        returninstance; }

Test Kit:

1  Packagecom.xxyh.jdbc.test;2 Importjava.sql.Connection;3 ImportJava.sql.ResultSet;4 Importjava.sql.SQLException;5 Importjava.sql.Statement;6 Importcom.xxyh.jdbc.JdbcUtils;7 ImportCom.xxyh.jdbc.JdbcUtilsSingleton;8  Public classJdbcutilssingletontest {9      Public Static voidMain (string[] args)throwsSQLException {TenConnection conn =NULL; OneStatement stmt =NULL; AResultSet rs =NULL; -          -         Try {  theconn =jdbcutilssingleton.getinstance (). getconnection (); -stmt =conn.createstatement (); -rs = Stmt.executequery ("SELECT * from User"); -              +              while(Rs.next ()) { -System.out.println (Rs.getobject ("id") + "\ T" + rs.getobject ("name") + "\ T" + +Rs.getobject ("Birthday") + "\ T" + rs.getobject ("Money"))); A             } at}finally { - Jdbcutils.close (RS, stmt, conn); -         } -     } -}

"Test Result": 1 zhangs 1985-01-01 100.02 Lisi 1986-01-01 200.03 Wangwu 1987-01-01 300.0

JDBC Learning Note (4): A single-case toolkit