Some methods of DBCP connection pooling

Create a connection

Connection conn =null;          =null;         = dbcp.getconnection ();            St=conn.createstatement ();

1. Batch processing Addbatch ()

You can centralize the strings of multiple operational databases

String sql1= "Select ..... ";

String sql2= "Select ..... ";

..............

St.addbatch (SQL1);

St.addbatch (SQL2);

..............

St.executebatch (); Centralized processing

St.clearbatch ();//better clean up in time, otherwise the string will remain in Addbatch

2. Object Management Setautocommit (Boolean);

Some logic must be in one transaction to complete: Through transaction management You can have multiple logic complete in one transaction.

Thing characteristics: ACID

Atomicty atomicity: The transaction must be an atomic unit of work, and the modification of the data is either fully executed or not executed.

Consistency consistency: When a transaction is complete, all data must be in a consistent state.

Isolation isolation: Modifications made by concurrent firms must be isolated from other concurrent transactions.
Durability persistence: After a transaction completes, its effect on the system is permanent.

Conn.setautocommit (FALSE); Turn off autocommit, default is True

St.executeupdate (SQL1);

St.executeupdate (SQL2);

Conn.commit (); Manual commit, Action SQL1 and SQL2 are executed, or both do not execute

3.preparedStatement: Pre-compiled to effectively prevent injection attacks

String sql= "SELECT * from emp_xx where ename = Upper (?) and Sal >?";

Connection conn=dbcp.getconnection ();
PreparedStatement p=conn.preparestatement (SQL);
P.setstring (1, "Scott");
P.setdouble (2, 1000.0);
ResultSet Rs=p.executequery ();

4. Result set

@Test Public voidTest8 () {String SQL= "SELECT * FROM Emp_xx"; Connection Conn=NULL; ResultSet RS=NULL; Try{conn=dbcp.getconnection (); PreparedStatement PS=conn.preparestatement (SQL); RS=Ps.executequery (); ResultSetMetaData Meta=rs.getmetadata ();//get the metadata set        intNumber= Meta.getcolumncount ();//get the number of columns in the result setSystem.out.println (Meta.getcolumntypename (1));//gets the ordinal number of the type column of a column starting from 1         for(inti = 1; I <=number; i++) {String columname=meta.getcolumnname (i);//traverse to get all column names in the result setSystem.out.println (columname); }            } Catch(SQLException e) {//TODO auto-generated Catch blockE.printstacktrace (); }}

5. Scrollable result set

@Test Public voidTest9 () {String SQL= "Select Ename,sal from Emp_xx order by Sal"; Connection Conn=NULL; ResultSet RS=NULL; Try{conn=dbcp.getconnection (); //If you want to create a scrollable result set, statement or preparestatement is created differently://Statement stmt = conn.createstatement (Type,concurrney);//PreparedStatement PS = conn.preparestatement (Sql,type,concurrney);            /*** Where type is value: * type_forward_only: Default, only read down * type_scroll_insenstive: Scrollable , not aware of data changes * type_scroll_senstive: scrollable, perceptual data changes * where Concurrency: * concur_read_only: Only Read, Cannot update * concur_updatable: Can update the result set*/Statement stmt=conn.createstatement (resultset.type_scroll_sensitive, resultset.concur_updatable); RS=stmt.executequery (SQL); /*** The usual way to move pointers: * First: pointer moves to number one * Last: pointer moves to final bar * Beforefirst:              * Afterlast: * IsFirst: Determine whether to point to the first * Islast: is the last bar * Isbeforefirst:               * Isafterlast: * Relative: Move to the relative position of the current pointer * Next: Move to the next * previous: Move to the previous bar * Absolute: Move to absolute position*/             //To update the result set data:Rs.absolute (3);//Move Pointer to 3rd recordRs.updatedouble (2, 2000);//Update the second column of data into 1555//Rs.updaterow ();//updating data source dataRs.first ();  while(Rs.next ()) {System.out.print (rs.getstring ("ename") + ""); System.out.println (Rs.getstring ("Sal")); }                    } Catch(SQLException e) {e.printstacktrace (); }finally {            if(conn!=NULL){                Try{conn.close (); } Catch(SQLException e) {//TODO auto-generated Catch blockE.printstacktrace (); }            }        }        }

Some methods of DBCP connection pooling