Java Database programming

JDBC (Java database Connectivity): A set of database programming APIs available in Java that defines a standard Java class library (in java.sql and javax.sql packages) to access the database. Using JDBC, you can write programs in Java, implement a connection to a specific database, send SQL statements to a database, implement specific operations on the database, and process the results of a database return. 。

1.JDBC Programming Six steps: (1). Select the JDBC driver type according to the database used by the application.

(2). Connect to the database and get the connection object.

(3). Create a statement object from connection.

(4). Use the Statement object to submit the SQL statement.

(5). Operation result set.

(6). Recycle database resources.

2. Select the JDBC driver type (1). LDBC-ODBC Bridge plus ODBC driver

(2). Local API and some Java-based drivers

(3). Pure Java Driver for database middleware

(4). Native protocol Pure Java driver (best performance)

Example of 3.JDBC Connection code:

 Packagecom;Importjava.io.IOException;ImportJava.io.InputStream;Importjava.sql.Connection;ImportJava.sql.DriverManager;Importjava.sql.PreparedStatement;ImportJava.sql.ResultSet;Importjava.sql.SQLException;Importjava.sql.Statement;Importjava.util.Properties;/*** JDBC Helper class * *@author * */ Public classJdbcutil {/*it is best to save with a configuration file*/    Private StaticString driver;//Drive    Private StaticString URL;//Connection String    Private StaticString user;//User name    Private StaticString password;//Password    Private StaticConnection Conn;//Connection Object    Private StaticPreparedStatement pstmt;//PreparedStatement Object    Private StaticResultSet rs;//ResultSet Object    /*Load Database driver*/    Static{loadProperties (); Try{class.forname (driver); } Catch(ClassNotFoundException e) {Throw NewRuntimeException (e); }    }    PrivateJdbcutil () {}/*** Read configuration file*/    Private Static voidloadProperties () {Properties Properties=NewProperties (); InputStream in=Thread.CurrentThread (). GetClass (). getResourceAsStream ("/com/lovo/day2/jdbc.properties"); Try{properties.load (in); } Catch(IOException e) {Throw NewRuntimeException (e); } Driver= Properties.getproperty ("Driver"); URL= Properties.getproperty ("url"); User= Properties.getproperty ("User"); Password= Properties.getproperty ("Password"); }    /*** Get Database connection * *@returnConnection Object*/     Public StaticConnection getconnection () {Try {            returnconn =drivermanager.getconnection (URL, user, password); } Catch(SQLException e) {Throw NewRuntimeException (e); }    }    /*** Release ResultSet resources * *@paramRS*/     Public Static voidClose (ResultSet rs) {Try {            if(NULL!=rs) rs.close (); } Catch(SQLException e) {Throw NewRuntimeException (e); }    }    /*** Release ResultSet resources * *@paramRS*/     Public Static voidClose (Statement stmt) {Try {            if(NULL!=stmt) stmt.close (); } Catch(SQLException e) {Throw NewRuntimeException (e); }    }    /*** Release ResultSet resources * *@paramRS*/     Public Static voidClose (Connection conn) {Try {            if(NULL!=conn) conn.close (); } Catch(SQLException e) {Throw NewRuntimeException (e); }    }    /*** FREE All resources*/     Public Static voidClose () {Try {            if(NULL! = RS &&!rs.isclosed ())            {Rs.close (); } RS=NULL; } Catch(SQLException e) {Throw NewRuntimeException (e); } finally {            Try {                if(NULL! = pstmt &&!pstmt.isclosed ())                {Pstmt.close (); } pstmt=NULL; } Catch(SQLException e) {Throw NewRuntimeException (e); } finally {                Try{SYSTEM.OUT.PRINTLN (conn); if(NULL! = Conn &&!conn.isclosed ())                    {Conn.close (); } Conn=NULL; } Catch(SQLException e) {Throw NewRuntimeException (e); }            }        }    }    /*** Perform additions and deletions * *@paramSQL * SQL statement to be executed *@paramparams * The parameters of a placeholder in an SQL statement *@returnnumber of rows affected*/     Public Static intexecuteupdate (String sql, Object ... params) {Try {            if(NULL==conn) getconnection (); Pstmt=conn.preparestatement (SQL); if(NULL! = params) {//set parameters for the SQL statement placeholder                 for(inti = 0; i < params.length; i++) {Pstmt.setobject (i+ 1, Params[i]); }            }            returnpstmt.executeupdate (); } Catch(SQLException e) {Throw NewRuntimeException (e); }    }    /*** Implementation Query * *@paramSQL * Query SQL statement to execute *@paramparams * The parameters of a placeholder in an SQL statement *@returnquery result set ResultSet object*/     Public StaticResultSet executeQuery (String sql, Object ... params) {Try {            if(NULL==conn) getconnection (); Pstmt=conn.preparestatement (SQL); if(NULL! = params) {//set parameters for the SQL statement placeholder                 for(inti = 0; i < params.length; i++) {Pstmt.setobject (i+ 1, Params[i]); }            }            returnrs =Pstmt.executequery (); } Catch(SQLException e) {Throw NewRuntimeException (e); }    }}

Java Database programming