JDBC (Connection Pool)--(I)

Custom connection Pooling one:    The 1.sun provides a connection pool interface Javax.sql.DataSource.    2. Define the connection pool myDataSource Implement Interface DataSource.    3. Using the collection LinkedList < Connection > Pool store multiple Connection objects. linkedlist Remove add operation is highly efficient. The connection object also invokes the getconnection in the tool class Jdbcutils as before. (first introduction to JDBC)    4. Write the method to get the connection getconnection (), get the connection instead of taking the object from the pool.    5. Write the method Backconnection () to return the connection. Return the objects obtained from the pool pool.    We need three of classes:
1.JDBCUtils (the first JDBC essay has an introduction to how to write)
2.MyDataSource
3.TestMyDataSource

Note: The junit used for testing.

First, the writing myDataSource method, here does not implement the interface datasource

 PackageCom.it.JDBC;Importjava.sql.Connection;Importjava.util.LinkedList;/** * @authorpayphone * @time 2017-10-07 custom connection pool, no enhanced Close method **/ Public classmyDataSource {Private StaticConnection Conn; Private StaticLinkedlist<connection> pool =NewLinkedlist<connection>(); /*** Construction Method initializes the number of connection pools, and can also be initialized with static blocks of code. * */     PublicmyDataSource () { for(inti = 0; I < 5; i++) {Conn=jdbcutils.getconnection ();        POOL.ADD (conn); } System.out.println ("---------Split Line---------"); }    /*** Get Connections **/     PublicConnection getconnection () {System.out.println ("Number of connections before:" +pool.size ()); Conn= Pool.remove (0); System.out.println ("Number of connections:" +pool.size ()); returnConn; }    /*** Return connection **/     Public voidbackconnection () {System.out.println ("Number of releases before connection:" +pool.size ());        POOL.ADD (conn); System.out.println ("Number of free connections:" +pool.size ()); }}

Second, the writing test method Testmydatasource

Package Com.it.TestJDBC;

Import java.sql.Connection;
Import java.sql.PreparedStatement;
Import Org.junit.Test;

Import Com.it.JDBC.JDBCUtils;
Import Com.it.JDBC.MyDataSource;

public class Testmydatasource {

@Test
public void Testadduser () {
Connection conn = null;
myDataSource MD = new myDataSource ();
PreparedStatement psmt = null;
try {
conn = Md.getconnection ();
String sql = "INSERT into T_user (ID,PWD) VALUES (?,?)";
PSMT = conn.preparestatement (sql);
Psmt.setint (1, 2015005);
Psmt.setstring (2, "2015005");
int rows = Psmt.executeupdate ();
if (Rows > 0) {
System.out.println ("Insert data successfully! ");
} else {
System.out.println ("Insert data failed! ");
}
} catch (Exception e) {
throw new RuntimeException (e);
} finally {
Jdbcutils.release (NULL, PSMT, NULL);
Md.backconnection ();
}
}
}

Custom connection pooling A code is not perfect, we call the tool class Jdbcutils.release method to release the object except Conn. The Md.backconnection method is also called to return the Conn.

In the code for custom connection Pool Two we will enhance the Close method. Call the tool class Jdbcutils.release method to return the connection.

JDBC (Connection Pool)--(I)