分享
 
 
 

一个Oracle数据库链接的JavaBean实例

王朝oracle·作者佚名  2008-05-31
窄屏简体版  字體: |||超大  

public class OracleConnectionManager {

private DBConnectionManager connMgr;

private final String poolName="Oracle";

private Connection conn;

public OracleConnectionManager() {

String userID = "system";

String passWord = "manager";

String JDBCDriver = "oracle.jdbc.driver.OracleDriver";

String JDBCDriverType = "jdbc:oracle:thin";

String DBHost = "127.0.0.1";

String Port = "1521";

String SID="sid";

String url = JDBCDriverType+":@"+DBHost + ":" + Port + ":" +SID;

connMgr = DBConnectionManager.getInstance();

if (DBConnectionManager.clients == 1){

connMgr.init(poolName, JDBCDriver, url, userID, password);

connMgr.init("egongOracle", JDBCDriver, JDBCDriverType+":@110.7.6.22:1521:egong", "abcusername", "abcpasswd");

}

}

public Connection getConnection() {

return (conn=connMgr.getConnection(poolName));

}

public Connection getConnection(String newOracle) {

return (conn=connMgr.getConnection(newOracle));

}

public void freeConnection() {

connMgr.freeConnection(poolName,conn);

}

public void freeConnection(String newOracle) {

connMgr.freeConnection(newOracle,conn);

}

}

public class DBConnectionManager {

static private DBConnectionManager instance=null; // The single instance

static public int clients=0;

private Vector drivers = new Vector();

private PrintWriter log;

private Hashtable pools = new Hashtable();

private final int MAX_CONN = 1000;

/**

* 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 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 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());

}

}

log.close();

}

/**

* 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(String poolName, String url, String user, String password, int max) {

/*

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);

}

}

*/

DBConnectionPool pool =

new DBConnectionPool(poolName, url, user, password, max);

pools.put(poolName, pool);

log("Initialized pool " + poolName);

}

public void init(String poolName, String driver, String url, String user, String passwd) {

init(poolName, driver, url, user, passwd, MAX_CONN);

}

/**

* Loads properties and initializes the instance with its values.

*/

public void init(String poolName, String driver, String url, String user, String passwd, int maxconn) {

/*

InputStream is = getClass().getResourceAsStream("/db.properties");

Properties dbProps = new Properties();

try {

dbProps.load(is);

}

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");

String logFile = "." + File.separator + "logs" + File.separator + "dbpool";

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);

}

*/

log = new PrintWriter(System.err);

loadDrivers(driver);

createPools(poolName, url, user, passwd, maxconn);

}

/**

* 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(String driverClassName) {

/*

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);

}

}

*/

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 Connection getConnection() {

Connection con = null;

if (freeConnections.size() > 0) {

// Pick the first Connection in the Vector

// to get round-robin usage

con = (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 Connection getConnection(long timeout) {

long startTime = new Date().getTime();

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()) {

Connection con = (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 Connection newConnection() {

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;

}

}

}

 
 
 
免责声明:本文为网络用户发布,其观点仅代表作者个人观点,与本站无关,本站仅提供信息存储服务。文中陈述内容未经本站证实,其真实性、完整性、及时性本站不作任何保证或承诺,请读者仅作参考,并请自行核实相关内容。
2023年上半年GDP全球前十五强
 百态   2023-10-24
美众议院议长启动对拜登的弹劾调查
 百态   2023-09-13
上海、济南、武汉等多地出现不明坠落物
 探索   2023-09-06
印度或要将国名改为“巴拉特”
 百态   2023-09-06
男子为女友送行,买票不登机被捕
 百态   2023-08-20
手机地震预警功能怎么开?
 干货   2023-08-06
女子4年卖2套房花700多万做美容:不但没变美脸,面部还出现变形
 百态   2023-08-04
住户一楼被水淹 还冲来8头猪
 百态   2023-07-31
女子体内爬出大量瓜子状活虫
 百态   2023-07-25
地球连续35年收到神秘规律性信号,网友:不要回答!
 探索   2023-07-21
全球镓价格本周大涨27%
 探索   2023-07-09
钱都流向了那些不缺钱的人,苦都留给了能吃苦的人
 探索   2023-07-02
倩女手游刀客魅者强控制(强混乱强眩晕强睡眠)和对应控制抗性的关系
 百态   2020-08-20
美国5月9日最新疫情:美国确诊人数突破131万
 百态   2020-05-09
荷兰政府宣布将集体辞职
 干货   2020-04-30
倩女幽魂手游师徒任务情义春秋猜成语答案逍遥观:鹏程万里
 干货   2019-11-12
倩女幽魂手游师徒任务情义春秋猜成语答案神机营:射石饮羽
 干货   2019-11-12
倩女幽魂手游师徒任务情义春秋猜成语答案昆仑山:拔刀相助
 干货   2019-11-12
倩女幽魂手游师徒任务情义春秋猜成语答案天工阁:鬼斧神工
 干货   2019-11-12
倩女幽魂手游师徒任务情义春秋猜成语答案丝路古道:单枪匹马
 干货   2019-11-12
倩女幽魂手游师徒任务情义春秋猜成语答案镇郊荒野:与虎谋皮
 干货   2019-11-12
倩女幽魂手游师徒任务情义春秋猜成语答案镇郊荒野:李代桃僵
 干货   2019-11-12
倩女幽魂手游师徒任务情义春秋猜成语答案镇郊荒野:指鹿为马
 干货   2019-11-12
倩女幽魂手游师徒任务情义春秋猜成语答案金陵:小鸟依人
 干货   2019-11-12
倩女幽魂手游师徒任务情义春秋猜成语答案金陵:千金买邻
 干货   2019-11-12
 
推荐阅读
 
 
 
>>返回首頁<<
 
靜靜地坐在廢墟上,四周的荒凉一望無際,忽然覺得,淒涼也很美
© 2005- 王朝網路 版權所有