Java JDBC Operations Database common code

1. Preparatory work

1 "

Create a new configuration file named Jdbc.properties to put it in SRC

2 "In the project to import the JDBC driver, pay attention to connect the different databases, the use of the driver is not the same, these can be found on the Internet

For more details on how to import jars, refer to http://blog.csdn.net/mazhaojuan/article/details/21403717

2. Code

1 ImportJava.io.InputStream;2 Importjava.sql.Connection;3 ImportJava.sql.DriverManager;4 ImportJava.sql.ResultSet;5 Importjava.sql.SQLException;6 Importjava.sql.Statement;7 Importjava.util.Properties;8 9  Public classMain {Ten      Public Static voidMain (string[] args) { OneDbutil Dbutil =Newdbutil (); ADBUTIL.R ("Select * FROM table"); -     } - } the  - classdbutil{ -     /** - * Get database connection +      * @return -      * @throwsException +      */ A      PublicConnection getconnection ()throwsexception{ at         //1. Create the configuration file and get the object input stream -InputStream is = This. GetClass (). getClassLoader (). getResourceAsStream ("Jdbc.properties.txt"); -         //2. Create Propetities -Properties JDBC =NewProperties (); - Jdbc.load (IS); -         //3. The corresponding value is obtained by means of Key-value inString Driver = jdbc.getproperty ("Driver"); -String url = jdbc.getproperty ("url"); toString user = Jdbc.getproperty ("User"); +String Password = jdbc.getproperty ("Password"); -         //4. Class objects when carrying a load the Class.forName (driver); *         //5 getting connected via DriverManager $Connection Connection =drivermanager.getconnection (Url,user,password);Panax Notoginseng         returnconnection; -          the     } +     /** A * Ways to release resources the      * @paramConnection +      * @paramStatement -      * @paramResultSet $      */ $      Public voidrelease (Connection connection,statement statement,resultset ResultSet) { -         Try { -             if(resultset!=NULL){ the resultset.close (); -             }Wuyi             if(statement!=NULL){ the statement.close (); -             } Wu             if(connection!=NULL){ - connection.close (); About             } $}Catch(SQLException e) { - e.printstacktrace (); -         } -          A     } +     /** the * Methods for querying the database -      * @paramSQL string, the SQL statement to execute if there are variables, use ' + variable + ' $      */ the      Public voidR (String sql) { theConnection Connection =NULL; theStatement Statement =NULL; theResultSet ResultSet =NULL; -         Try { inConnection =getconnection (); thestatement =connection.createstatement (); theResultSet =statement.executequery (SQL); About              while(Resultset.next ()! =false){ the                 //Here are some other things you can do theSystem.out.println (resultset.getstring (1)); the             } +}Catch(Exception e) { - e.printstacktrace (); the}finally {Bayi Release (connection, statement, ResultSet); the         } the     } -     /** - * How to change database records and additions the      * @paramSQL string, the SQL statement to execute if there are variables, use ' + variable + ' the      */ the      Public voidCUD (String sql) { theConnection Connection =NULL; -Statement Statement =NULL; theResultSet ResultSet =NULL; the         Try { theConnection =getconnection ();94statement =connection.createstatement (); theResultSet =statement.executequery (SQL); the              the             //This can be judged based on the return result, whether the statement executes successfully98 System.out.println (resultSet); About}Catch(Exception e) { - e.printstacktrace ();101}finally {102 Release (connection, statement, ResultSet);103         }104     } the     106}

Java JDBC Operations Database common code