JNDI使用小记

JDNI使用小记

       < Resource name ="jdbc/mysql"
                auth ="Container" 　　
                   type ="javax.sql.DataSource"
                   maxActive ="100"
                   maxIdle ="30"
                   maxWait ="60" 　　
                   wait_timeout ="18800"
                   timeBetweenEvictionRunsMillis ="300000" 　　
                   minEvictableIdleTimeMillis ="600000"
                   username ="root"
                   password ="root" 　　
                   driverClassName ="com.mysql.jdbc.Driver" 　　
                   url ="jdbc:mysql://localhost:3306/studentjxy?comautoReconnect=true&failOverReadOnly=false" 　　
                   removeAbandoned ="true"
                   removeAbandonedTimeout ="60" 　　
                   logAbandoned ="true" />

package db;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;

public class DBCache {
       private InitialContext ic ;
       private Map<String, DataSource> cache ;
       private static DBCache instance = new DBCache();

       private DBCache() {
             try {
                   ic = new InitialContext();
            } catch (NamingException e) {
                  e.printStackTrace();
            }
             cache = Collections.synchronizedMap( new HashMap<String, DataSource>());
      }

       public static DBCache getInstance() {
             return instance ;
      }

       public Connection getDBConn(String dataSourceName) throws SQLException,
                  NamingException {
            Connection conn = null ;
            conn = getDataSource(dataSourceName).getConnection();
             return conn;
      }

       public DataSource getDataSource(String dataSourceName)
                   throws NamingException {
             if (cache .containsKey(dataSourceName)) {
                   return cache .get(dataSourceName);
            } else {
                  DataSource newDataSource = (DataSource) ic .lookup(dataSourceName);
                   cache .put(dataSourceName, newDataSource);
                   return newDataSource;
            }
      }

       public void removeDateSouceOffCache(String dataSourceName) {
             try {
                  DataSource ds = cache .get(dataSourceName);
                  ds.getConnection().close();
                   cache .remove(dataSourceName);
            } catch (Exception ex) {
            }
      }

       public static void freeConn(Connection conn) {
             freeConn(conn, null, null );
      }

       public static void freeConn(Connection connection, Statement statement) {
             freeConn(connection, statement, null);
      }

       public static void freeConn(Connection conn, Statement ps, ResultSet rs) {
             try {
                   try {
                         if (rs != null)
                              rs.close();
                  } finally {
                         try {
                               if (ps != null)
                                    ps.close();
                        } finally {
                               if (conn != null)
                                    conn.close();
                        }
                  }
            } catch (SQLException ex) {
                  ex.printStackTrace();
            }
      }
}

package db;

import java.sql.Connection;
import java.sql.SQLException;

import javax.naming.NamingException;

public class DBManager {

       public Connection getConnection() {

            DBCache db = DBCache. getInstance();
            Connection conn = null ;
             try {
                  conn = db.getDBConn( "java:comp/env/jdbc/mysql" );
            } catch (SQLException e) {
                   // TODO Auto-generated catch block
                  e.printStackTrace();
            } catch (NamingException e) {
                   // TODO Auto-generated catch block
                  e.printStackTrace();
            }
             return conn;
      }

}