java oracle jdbc 連接池

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package jcoapp;

/**
 *
 * @author luolai
 */
import java.io.*;
import java.sql.*;
import java.util.*;
import java.util.Date;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * This class is a Singleton that provides access to one or many connection
 * pools defined in a Property file. A client gets access to the single instance
 * through the static getInstance() method and can then check-out and check-in
 * connections from a pool. When the client shuts down it should call the
 * release() method to close all open connections and do other clean up.
 */
public class DBConnectionManager {

    static private DBConnectionManager instance;       // The single instance
    static private int clients;
    private Vector drivers = new Vector();
    private PrintWriter log;
    private Hashtable pools = new Hashtable();

    /**
     * Returns the single instance, creating one if it's the first time this
     * method is called.
     *
     * @return DBConnectionManager The single instance.
     */
    static synchronized public DBConnectionManager getInstance() {
        if (instance == null) {
            instance = new DBConnectionManager();
        }
        clients++;
        return instance;
    }

    /**
     * A private constructor since this is a Singleton
     */
    private DBConnectionManager() {
        init();
    }

    /**
     * Returns a connection to the named pool.
     *
     * @param name The pool name as defined in the properties file
     * @param con The Connection
     */
    public void freeConnection(String name, Connection con) {
        DBConnectionPool pool = (DBConnectionPool) pools.get(name);
        if (pool != null) {
            pool.freeConnection(con);
        }
    }

    /**
     * Returns an open connection. If no one is available, and the max number of
     * connections has not been reached, a new connection is created.
     *
     * @param name The pool name as defined in the properties file
     * @return Connection The connection or null
     */
    public java.sql.Connection getConnection(String name) {
        DBConnectionPool pool = (DBConnectionPool) pools.get(name);
        if (pool != null) {
            return pool.getConnection();
        }
        return null;
    }

    /**
     * Returns an open connection. If no one is available, and the max number of
     * connections has not been reached, a new connection is created. If the max
     * number has been reached, waits until one is available or the specified
     * time has elapsed.
     *
     * @param name The pool name as defined in the properties file
     * @param time The number of milliseconds to wait
     * @return Connection The connection or null
     */
    public java.sql.Connection getConnection(String name, long time) {
        DBConnectionPool pool = (DBConnectionPool) pools.get(name);
        if (pool != null) {
            return pool.getConnection(time);
        }
        return null;
    }

    /**
     * Closes all open connections and deregisters all drivers.
     */
    public synchronized void release() {
        // Wait until called by the last client
        if (--clients != 0) {
            return;
        }

        Enumeration allPools = pools.elements();
        while (allPools.hasMoreElements()) {
            DBConnectionPool pool = (DBConnectionPool) allPools.nextElement();
            pool.release();
        }
        Enumeration allDrivers = drivers.elements();
        while (allDrivers.hasMoreElements()) {
            Driver driver = (Driver) allDrivers.nextElement();
            try {
                DriverManager.deregisterDriver(driver);
                log("Deregistered JDBC driver " + driver.getClass().getName());
            } catch (SQLException e) {
                log(e, "Can't deregister JDBC driver: " + driver.getClass().getName());
            }
        }
    }

    /**
     * Creates instances of DBConnectionPool based on the properties. A
     * DBConnectionPool can be defined with the following properties:
     * <PRE>
     * <poolname>.url         The JDBC URL for the database
     * <poolname>.user        A database user (optional)
     * <poolname>.password    A database user password (if user specified)
     * <poolname>.maxconn     The maximal number of connections (optional)
     * </PRE>
     *
     * @param props The connection pool properties
     */
    private void createPools(Properties props) {
        Enumeration propNames = props.propertyNames();
        while (propNames.hasMoreElements()) {
            String name = (String) propNames.nextElement();
            if (name.endsWith(".url")) {
                String poolName = name.substring(0, name.lastIndexOf("."));
                String url = props.getProperty(poolName + ".url");
                if (url == null) {
                    log("No URL specified for " + poolName);
                    continue;
                }
                String user = props.getProperty(poolName + ".user");
                String password = props.getProperty(poolName + ".password");
                String maxconn = props.getProperty(poolName + ".maxconn", "0");
                int max;
                try {
                    max = Integer.valueOf(maxconn).intValue();
                } catch (NumberFormatException e) {
                    log("Invalid maxconn value " + maxconn + " for " + poolName);
                    max = 0;
                }
                DBConnectionPool pool =
                        new DBConnectionPool(poolName, url, user, password, max);
                pools.put(poolName, pool);
                log("Initialized pool " + poolName);
            }
        }
    }

    /**
     * Loads properties and initializes the instance with its values.
     */
    private void init() {
        InputStream is = getClass().getResourceAsStream("logon.properties");
        FileInputStream inputFile;
        try {
            inputFile = new FileInputStream("logon.properties");
        } catch (FileNotFoundException ex) {
            Logger.getLogger(DBConnectionManager.class.getName()).log(Level.SEVERE, null, ex);
            System.out.println(ex.getMessage());
            return;
        }
        Properties dbProps = new Properties();
        try {
            dbProps.load(inputFile);
        } catch (Exception e) {
            System.err.println("Can't read the properties file. "
                    + "Make sure db.properties is in the CLASSPATH");
            return;
        }
        String logFile = dbProps.getProperty("logfile", "DBConnectionManager.log");
        try {
            log = new PrintWriter(new FileWriter(logFile, true), true);
        } catch (IOException e) {
            System.err.println("Can't open the log file: " + logFile);
            log = new PrintWriter(System.err);
        }
        loadDrivers(dbProps);
        createPools(dbProps);
    }

    /**
     * Loads and registers all JDBC drivers. This is done by the
     * DBConnectionManager, as opposed to the DBConnectionPool, since many pools
     * may share the same driver.
     *
     * @param props The connection pool properties
     */
    private void loadDrivers(Properties props) {
        String driverClasses = props.getProperty("drivers");
        StringTokenizer st = new StringTokenizer(driverClasses);
        while (st.hasMoreElements()) {
            String driverClassName = st.nextToken().trim();
            try {
                Driver driver = (Driver) Class.forName(driverClassName).newInstance();
                DriverManager.registerDriver(driver);
                drivers.addElement(driver);
                log("Registered JDBC driver " + driverClassName);
            } catch (Exception e) {
                log("Can't register JDBC driver: "
                        + driverClassName + ", Exception: " + e);
            }
        }
    }

    /**
     * Writes a message to the log file.
     */
    private void log(String msg) {
        log.println(new Date() + ": " + msg);
    }

    /**
     * Writes a message with an Exception to the log file.
     */
    private void log(Throwable e, String msg) {
        log.println(new Date() + ": " + msg);
        e.printStackTrace(log);
    }

    /**
     * This inner class represents a connection pool. It creates new connections
     * on demand, up to a max number if specified. It also makes sure a
     * connection is still open before it is returned to a client.
     */
    class DBConnectionPool {

        private int checkedOut;
        private Vector freeConnections = new Vector();
        private int maxConn;
        private String name;
        private String password;
        private String URL;
        private String user;

        /**
         * Creates new connection pool.
         *
         * @param name The pool name
         * @param URL The JDBC URL for the database
         * @param user The database user, or null
         * @param password The database user password, or null
         * @param maxConn The maximal number of connections, or 0 for no limit
         */
        public DBConnectionPool(String name, String URL, String user, String password,
                int maxConn) {
            this.name = name;
            this.URL = URL;
            this.user = user;
            this.password = password;
            this.maxConn = maxConn;
        }

        /**
         * Checks in a connection to the pool. Notify other Threads that may be
         * waiting for a connection.
         *
         * @param con The connection to check in
         */
        public synchronized void freeConnection(Connection con) {
            // Put the connection at the end of the Vector
            freeConnections.addElement(con);
            checkedOut--;
            notifyAll();
        }

        /**
         * Checks out a connection from the pool. If no free connection is
         * available, a new connection is created unless the max number of
         * connections has been reached. If a free connection has been closed by
         * the database, it's removed from the pool and this method is called
         * again recursively.
         */
        public synchronized java.sql.Connection getConnection() {
            java.sql.Connection con = null;
            if (freeConnections.size() > 0) {
                // Pick the first Connection in the Vector
                // to get round-robin usage
                con = (java.sql.Connection) freeConnections.firstElement();
                freeConnections.removeElementAt(0);
                try {
                    if (con.isClosed()) {
                        log("Removed bad connection from " + name);
                        // Try again recursively
                        con = getConnection();
                    }
                } catch (SQLException e) {
                    log("Removed bad connection from " + name);
                    // Try again recursively
                    con = getConnection();
                }
            } else if (maxConn == 0 || checkedOut < maxConn) {
                con = newConnection();
            }
            if (con != null) {
                checkedOut++;
            }
            return con;
        }

        /**
         * Checks out a connection from the pool. If no free connection is
         * available, a new connection is created unless the max number of
         * connections has been reached. If a free connection has been closed by
         * the database, it's removed from the pool and this method is called
         * again recursively. <P> If no connection is available and the max
         * number has been reached, this method waits the specified time for one
         * to be checked in.
         *
         * @param timeout The timeout value in milliseconds
         */
        public synchronized java.sql.Connection getConnection(long timeout) {
            long startTime = new Date().getTime();
            java.sql.Connection con;
            while ((con = getConnection()) == null) {
                try {
                    wait(timeout);
                } catch (InterruptedException e) {
                }
                if ((new Date().getTime() - startTime) >= timeout) {
                    // Timeout has expired
                    return null;
                }
            }
            return con;
        }

        /**
         * Closes all available connections.
         */
        public synchronized void release() {
            Enumeration allConnections = freeConnections.elements();
            while (allConnections.hasMoreElements()) {
                java.sql.Connection con = (java.sql.Connection) allConnections.nextElement();
                try {
                    con.close();
                    log("Closed connection for pool " + name);
                } catch (SQLException e) {
                    log(e, "Can't close connection for pool " + name);
                }
            }
            freeConnections.removeAllElements();
        }

        /**
         * Creates a new connection, using a userid and password if specified.
         */
        private java.sql.Connection newConnection() {
            java.sql.Connection con = null;
            try {
                if (user == null) {
                    con = DriverManager.getConnection(URL);
                } else {
                    con = DriverManager.getConnection(URL, user, password);
                }
                log("Created a new connection in pool " + name);
            } catch (SQLException e) {
                log(e, "Can't create a new connection for " + URL);
                return null;
            }
            return con;
        }
    }

    public static void main(String[] args) {
        Connection con = DBConnectionManager.getInstance().getConnection("wms");
        try {
            Statement stmt = con.createStatement();
            String sql = "select t4.name,t2.event_desc,t3.endpoint_queue_id,t3.error_count Tries,case t3.status when 5 then 'Succeeded' when 6 then 'Failed' else '' end status,"
                    + "t.msg_id,to_char(t.when_created,'yyyy-mm-dd HH24:MI:SS') when_created,t.source_uri,t.data "
                    + "from eisprod.cl_message t  "
                    + "inner join eisprod.cl_event_master t2 on t.event_id=t2.event_id "
                    + "inner join eisprod.cl_endpoint_queue t3 on t.msg_id=t3.msg_id "
                    + "inner join eisprod.cl_endpoint t4 on t3.endpoint_id=t4.endpoint_id "
                    + "where 1=1 and round((sysdate-to_date(to_char(t.when_created,'yyyymmddhh24miss'),'yyyy-mm-dd hh24:mi:ss'))*24*60*60)<= 80000"
                    //+"and to_char(t.when_created,'yyyy-mm-dd')=to_char(sysdate-1,'yyyy-mm-dd') and t3.error_count>='2' "
                    + "and t3.status='6'";
            ResultSet rs = stmt.executeQuery(sql);
            while (rs.next()) {
                String xmldata = rs.getString("data");
                //獲取錯誤的詳細信息
                XmlDom4J dom4j = new XmlDom4J();
                String tmp = dom4j.parseDocument(rs.getString("data"), "STOREDISTRO", "DISTRO_NBR").trim()
                        + dom4j.parseDocument(rs.getString("data"), "InboundASN", "SHPMT_NBR").trim()
                        + dom4j.parseDocument(rs.getString("data"), "PurchaseOrder", "PO_NBR").trim()
                        + dom4j.parseDocument(rs.getString("data"), "VendorMaster", "VENDOR_ID").trim()
                        + dom4j.parseDocument(rs.getString("data"), "StoreMaster", "STORE_NBR").trim()
                        + dom4j.parseDocument(rs.getString("data"), "ItemMaster", "SIZE_DESC").trim()
                        + dom4j.parseDocument(rs.getString("data"), "ItemMaster", "COLOR").trim()
                        + dom4j.parseDocument(rs.getString("data"), "ItemMaster", "STYLE").trim();
                if (!tmp.equals("")) {
                    System.out.println("EIS ERROR KEY:" + tmp);
                    String subsql = "select (error_seq_nbr) error_seq_nbr,(msg.msg) msg from ("
                            + "select max(t.error_seq_nbr) error_seq_nbr from inpt_store_distro t where  distro_nbr='" + tmp + "' "
                            + "union "
                            + "select max(t.error_seq_nbr) error_seq_nbr from inpt_asn_hdr t where  shpmt_nbr='" + tmp + "' "
                            + "union "
                            + "select max(t.error_seq_nbr) error_seq_nbr from inpt_po_hdr t where  po_nbr='" + tmp + "'  "
                            + "union "
                            + "select max(t.error_seq_nbr) error_seq_nbr from inpt_vendor_master t where  vendor_id='" + tmp + "' "
                            + "union "
                            + "select max(t.error_seq_nbr) error_seq_nbr from inpt_store_master t where  store_nbr='" + tmp + "' "
                            + "union "
                            + "select max(t.error_seq_nbr) error_seq_nbr from inpt_item_master t where  trim(size_desc)||trim(color)||trim(style)='" + tmp + "' "
                            + ") t inner join msg_log msg on to_char(t.error_seq_nbr)=msg.ref_value_1 "
                            + "";
                    Statement stmt2 = con.createStatement();
                    ResultSet rs2 = stmt2.executeQuery(subsql);
                    while (rs2.next()) {
                        System.out.println("ERROR MESSAGE:" + rs2.getString("MSG"));
                    }
                }
            }
            DBConnectionManager.instance.freeConnection("wms", con);
        } catch (SQLException ex) {
            Logger.getLogger(DBConnectionManager.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}