连接池占用资源问题
本人第一次采用链接池链接数据库，可发现占用内存相当大。为什么会这样呢？
我的链接池代码如下：望各位高手指点一二！
package com.nc138.util;
import java.io.*;
import java.sql.*;
import java.util.*;
import java.util.Date;
public class DBConnectionManager {
static private DBConnectionManager instance; // 唯一实例
static private int clients;
private Vector drivers = new Vector();
private PrintWriter log;
private Hashtable pools = new Hashtable();
Statement stmt = null;
ResultSet rs = null;
/**
* 返回唯一实例.如果是第一次调用此方法,则创建实例
*
* @return DBConnectionManager 唯一实例
**/
static synchronized public DBConnectionManager getInstance() {
if (instance == null) {
instance = new DBConnectionManager();
}
clients++;
return instance;
}
/**
* 建构函数私有以防止其它对象创建本类实例
*/
private DBConnectionManager() {
init();
}
/**
* 将连接对象返回给由名字指定的连接池
*
* @param name 在属性文件中定义的连接池名字
* @param con 连接对象
**/
public void freeConnection(String name, Connection con) {
DBConnectionPool pool = (DBConnectionPool) pools.get(name);
if (pool != null) {
pool.freeConnection(con);
}
}
public Connection getConnection(String name) {
DBConnectionPool pool = (DBConnectionPool) pools.get(name);
if (pool != null) {
return pool.getConnection();
}
return null;
}
public Connection getConnection(String name, long time) {
DBConnectionPool pool = (DBConnectionPool) pools.get(name);
if (pool != null) {
return pool.getConnection(time);
}
return null;
}
public synchronized void release() {
// 等待直到最后一个客户程序调用
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( "撤销JDBC驱动程序 " + driver.getClass().getName() + "的注册 ");
} catch (SQLException e) {
log(e, "无法撤销下列JDBC驱动程序的注册: " + driver.getClass().getName());
}
}
}
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( "没有为连接池 " + poolName + "指定URL ");
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( "错误的最大连接数限制: " + maxconn + " .连接池: " + poolName);
max = 0;
}
DBConnectionPool pool = new DBConnectionPool(poolName, url,
user, password, max);
pools.put(poolName, pool);
log( "成功创建连接池 " + poolName);
}
}
}
/**
* 读取属性完成初始化
*/
[解决办法]
感觉这样做连接池好复杂啊
我的理解是配置数据源时就可以配置数据池,
在servlet.xml里配置Resource.如以下代码:
<ResourceParams name= "jdbc/BookDB ">
<parameter>
<name> factory> </name>
<value> org.apache.commons.dbcp.BasicDataSourceFactory </value>
</parameter>
<parameter>
<name> maxActive </name>
<value> 100 </value>
</parameter>
<parameter>
<name> maxIdle </name>
<value> 30 </value>
</parameter>
<parameter>
<name> maxWait </name>
<value> 10000 </value>
</parameter>
<parameter>
<name> username </name>
<value> dbuser </value>
</parameter>
<parameter>
<name> password </name>
<value> 1234 </value>
</parameter>
<parameter>
<name> driverClassName </name>
<value> com.mysql.jdbc.Driver </value>
</parameter>
<parameter>
<name> url </name>
<value> jdbc:mysql://localhost:3306/BookDB?autoReconnect=true </value>
</parameter>
</ResourceParams>
再在web.xml里引用数据源,如以下代码:
<resource-ref>
<description> DB Connection </description>
<res-ref-name> jdbc/BookDB </res-ref-name>
<res-type> javax.sql.DataSource </res-type>
<res-auth> Container </res-auth>
</resource-ref>
最后在代码中通过JNDI取得连接,如以下代码:
public class BookDB {
private ArrayList books;
private DataSource ds=null;
public BookDB() throws Exception{
Context ctx=new InitialContext();
if(ctx==null)
throw new Exception( "No Context ");
ds=(DataSource)ctx.lookup( "java:com/env/jdbc/BookDB ");
}
public Connection getConnection() throws Exception {
return ds.getConnection();
}
public void closeConnection(Connection con){
try{
if(con!=null) con.close();
}catch(Exception e){
e.printStackTrace();
}
}
......
}
不知这样行不行，仅供参考。
[解决办法]
学习
