10g Connection Cache Callback Sample
묵시적인 Connection Cache는 데이터베이스 Connection이 캐시로부터 리턴 될 수 있는 기능을 제공 합니다. Callback 이 OracleConnection에 등록되면 Connection Cache는 Connection이 재 요구되기 전에 callback의 handleAbandonedConnection() 메소드를 호출 합니다. 만약 return값이 “true”라면 해당 Connection객체가 재 사용되어 지는 것입니다.
아래의 예제를 보시면서 이해하도록 하겠습니다. [OTN 자료]
---------------------------
CacheManager.java
---------------------------
/**
* @author Shrinivas Bhat
* @version 1.0
*
* Development Environment : Oracle JDeveloper 10g
* Name of the Application : CacheManager.java
* Creation/Modification History :
*
* Shrinivas 18-Jun-2004 Created
*
* Overview of Application : This class is used to create and maintain
* a connection cache.
**/
package oracle.otnsamples.jdbc10g;
// Java IO Exception class
import java.io.IOException;
// Java Utility classes
import java.util.Enumeration;
import java.util.Properties;
import java.util.ResourceBundle;
// Java SQL classes
import java.sql.Connection;
import java.sql.SQLException;
// Oracle JDBC classes
import oracle.jdbc.pool.OracleConnectionCacheManager;
import oracle.jdbc.pool.OracleDataSource;
/**
* This class is used to create and manage the connection cache.
*/
public class CacheManager {
// OracleDataSource object
private static OracleDataSource ods = null;
// Connection cache name
public static final String CACHE_NAME = "ConnectionCacheSample";
/**
* Default constructor
*/
public CacheManager() {
try {
// Create OracleDataSource object if it is not null
if( ods == null ) {
ods = new OracleDataSource();
// Configure the datasource
configureDataSource();
}
} catch(SQLException sqlEx ) {
sqlEx.printStackTrace();
} catch(IOException ioEx) {
ioEx.printStackTrace();
}
}
/**
* This method configures the Datasource with appropriate values of Host
* Name, User Name, Password etc. Note that the configuration parameters are
* stored in Connection.properties file.
*
*/
private void configureDataSource() throws SQLException, IOException {
// Load the properties file to get the connection information
// from the Connection.properties file
Properties prop = this.loadParams("Connection");
// Set the database properties
ods.setUser(prop.getProperty("UserName"));
ods.setPassword(prop.getProperty("Password"));
ods.setServerName(prop.getProperty("HostName"));
ods.setDatabaseName( prop.getProperty("SID") );
ods.setPortNumber(Integer.parseInt( prop.getProperty("Port") ) );
ods.setDriverType("thin");
// Enable implicit connection cache
ods.setConnectionCachingEnabled(true);
// Cache properties
Properties cacheProperties = new Properties();
// Set Max Limit for the Cache
cacheProperties.setProperty("MaxLimit", "4");
// Set the PropertyCheckInterval for 2 seconds
cacheProperties.setProperty("PropertyCheckInterval", "2");
// Set the AbandonedConnectionTimeout for 2 seconds
cacheProperties.setProperty("AbandonedConnectionTimeout", "2");
// Set the LowerThresholdLimit property to 25 percent (of the MaxLimit)
cacheProperties.setProperty("LowerThresholdLimit", "25");
// Get the OracleConnectionCacheManager instance
OracleConnectionCacheManager connMgr =
OracleConnectionCacheManager.getConnectionCacheManagerInstance();
// Create the cache
connMgr.createCache(CACHE_NAME,ods,cacheProperties);
}
/**
* This method reads a properties file, which is passed as the parameter
* and loads it into a java Properties object and returns the object.
*
* @param file - File name
*
* @return Properties object
*
* @throws IOException
*/
private Properties loadParams(String file) throws IOException {
// Loads a ResourceBundle and creates Properties from it
Properties prop = new Properties();
ResourceBundle bundle = ResourceBundle.getBundle(file);
Enumeration enum = bundle.getKeys();
String key = null;
while (enum.hasMoreElements()) {
key = (String) enum.nextElement();
prop.put(key, bundle.getObject(key) );
}
// Return properties
return prop;
}
/**
* This method returns a connection from the cache.
* @return Connection - Connection object
* @throws java.sql.SQLException - SQL Exception
*/
public Connection getConnection() throws SQLException {
return ods.getConnection();
}
}
------------------------
CallbackHandler.java
------------------------
/**
* @author Shrinivas Bhat
* @version 1.0
*
* Development Environment : Oracle JDeveloper 10g
* Name of the Application : CallbackHandler.java
* Creation/Modification History :
*
* Shrinivas 18-Jun-2004 Created
*
* Overview of Application : This class implements the
* OracleConnectionCacheCallback interface.
**/
package oracle.otnsamples.jdbc10g;
// Oracle JDBC imports
import oracle.jdbc.OracleConnection;
import oracle.jdbc.pool.OracleConnectionCacheCallback;
public class CallbackHandler implements OracleConnectionCacheCallback {
/**
* When the release connection callback is registered on a connection, and the
* cache from which the connection was retrieved is empty, then instead of
* the default behavior to wait for connections to be returned to the cache,
* this method is called by the cache.
* @param conn - OracleConnection object
* @param obj - Any Java object that needs to be processed in this method
*/
public void releaseConnection(OracleConnection conn, Object obj) {
try {
System.out.print("\nReleasing connection from thread \"");
System.out.println(((EmpManager)obj).getThreadName()+"\"");
// Release the connection
if (conn != null) {
conn.close();
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
/**
* When the handle abandoned connection callback is registered, the
* connection cache calls this method when a connection needs to be
* reclaimed.
* @param conn - OracleConnection object
* @param obj - Any Java object that needs to be processed in this method
* @return - true of false
*/
public boolean handleAbandonedConnection(OracleConnection conn, Object obj) {
try {
// Close the connection
if ( conn != null ) {
conn.close();
}
// Set a flag in the application to indicate the connection closure
if ( obj != null ) {
((EmpManager)obj).isActive = false;
}
} catch (Exception ex) {
ex.printStackTrace();
}
return true;
}
}
--------------------------
Emp.java
--------------------------
/**
* @author Shrinivas Bhat
* @version 1.0
*
* Development Environment : Oracle JDeveloper 10g
* Name of the Application : EmpManager.java
* Creation/Modification History :
*
* Shrinivas 18-Jun-2004 Created
*
* Overview of Application : This class connects to the database and
* displays the contents in the EMP table. This class makes use of CacheManager
* class to access the connection cache.
**/
package oracle.otnsamples.jdbc10g;
// Java SQL imports
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
// Oracle JDBC imports
import oracle.jdbc.OracleConnection;
import oracle.jdbc.OracleResultSet;
import oracle.jdbc.OracleStatement;
import oracle.jdbc.pool.OracleConnectionCacheManager;
import oracle.jdbc.rowset.OracleCachedRowSet;
/**
* This class is used to connect to the database and print the results.
* This extends the java.lang.Thread class and implements the run method. When
* the thread is started it calls the display() method which displays the
* contents from the emp table.
*/
public class Emp extends Thread {
// OracleConnection conn = null;
CacheManager cacheManager = null;
// OracleConnectionCacheManager object
OracleConnectionCacheManager connMgr = null;
// Thread name
String name = null;
// Boolean field that indicates whether the connection is active or not
boolean isActive = true;
// Connection cache name
public static final String CACHE_NAME = "ConnectionCacheSample";
/**
* Constructor.
* @param name - Name of the thread
*/
public Emp(String name) {
super(name);
this.name = name;
try {
if (cacheManager == null) {
cacheManager= new CacheManager();
connMgr = OracleConnectionCacheManager.getConnectionCacheManagerInstance();
// Start the thread
this.start();
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
/**
* The run method of the thread.
*/
public void run() {
System.out.println(" Starting thread " + name );
try {
this.display();
} catch (Exception ex) {
ex.printStackTrace();
}
}
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