连接池问题(有代码),请帮忙!

Question

package mytest;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import java.sql.*;
class DBPoolManager
{    static private DBPoolManager instance;
    static private int clients;
    private Vector drivers=new Vector();
    private Hashtable pools=new Hashtable();
    private DBPoolManager()
    {
        init();
    }    static synchronized public DBPoolManager getInstance()
    {
        if (instance == null)
        {
            instance = new DBPoolManager();
        }
        clients++;
        return instance;
    }
    private void init()
    {
        InputStream is = getClass().getResourceAsStream("/db.properties");
        Properties dbProps = new Properties();
        try
        {
            dbProps.load(is);
        }
        catch (Exception e)
        {
            System.err.println("Can not read the properties file. " + "Make sure db.properties is in the CLASSPATH");
            return;
        }        loadDrivers(dbProps);
        createPools(dbProps);
    }    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);            }
            catch (Exception e)
            {
            }
        }
    }
    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)
                {
                    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)
                {
                    max = 0;
                }
                ConnectionPool pool = new ConnectionPool(poolName, url, user, password, max,5,30000000);
                pools.put(poolName, pool);            }
        }
    }
    public Connection getConnection(String name)
    {
        Connection conn=null;
        ConnectionPool cp=(ConnectionPool)pools.get(name);
        if(cp!=null)
        {
            try{
                conn=cp.getConnection();
            }
            catch(Exception e)
            {}
        }
        return conn;
    }
    public void freeConnection(String name,Connection conn)
    {
        ConnectionPool pool=(ConnectionPool)pools.get(name);
        if(pool!=null)
        {
        pool.freeConnection(conn);
        }
    }
}

Answer 1

package mytest;import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class Servletone extends HttpServlet
{
    private DBPoolManager connMgr;    public void init(ServletConfig conf) throws ServletException
    {
        super.init(conf);
        connMgr = DBPoolManager.getInstance();
    }    public void service(HttpServletRequest req, HttpServletResponse res)
            throws IOException
    {        res.setContentType("text/html");
        PrintWriter out = res.getWriter();        Connection con=null;
        con = connMgr.getConnection("Test_Data.MDF");
        if (con == null)
        {
            out.println("database connection  failed.");
            return;
        }
        ResultSet rs = null;
        ResultSetMetaData md = null;
        Statement stmt = null;
        try
        {
            stmt = con.createStatement();
            rs = stmt.executeQuery("SELECT * FROM test");
            md = rs.getMetaData();
            out.println("<H1>member</H1>");
            while (rs.next()) {
                out.println("<BR>");
                for (int i = 1; i < md.getColumnCount(); i++)
                {
                    out.print(rs.getString(i) + ", ");
                }
            }
            stmt.close();
            rs.close();
        }
        catch (SQLException e) {
            e.printStackTrace(out);
        }
      connMgr.freeConnection("Test_Data.MDF",con);    }    public void destroy()
    {        super.destroy();
    }
}

Answer 2

麻烦你了,我这是日文操作系统,下面是日文的!
HttpConnector すべてのホストIPアドレスのサーバソケットをオープンしますサービス Tomcat-Standalone を起動しますApache Tomcat/4.0.3WebappLoader[]: クラスリポジトリを作業ディレクトリ D:\program\mytest\Tomcat\work に配備しますStandardManager[]: 乱数発生器のクラス java.security.SecureRandom のシードを生成していますStandardManager[]: 乱数発生器のシードの生成が完了しましたContextConfig[]: 証明書をリクエストの属性値に追加しますStandardWrapper[:default]: コンテナサーブレット default をロードしますStandardWrapper[:invoker]: コンテナサーブレット invoker をロードしますHttpConnector[8080] バックグラウンドスレッドを起動しますCan not read the properties file. Make sure db.properties is in the CLASSPATHStandardWrapperValve[servletone]: サーブレット servletone に例外を割り当てますjavax.servlet.ServletException: サーブレット servletone のServlet.init()が例外を投げましたjavax.servlet.ServletException: サーブレット servletone のServlet.init()が例外を投げました at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:935) at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:653) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:214) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:190) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566) at org.apache.catalina.valves.CertificatesValve.invoke(CertificatesValve.java:246) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943) at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2343) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566) at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:170) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:564) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline.java:566) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:472) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943) at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor.java:1012) at org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.java:1107) at java.lang.Thread.run(Thread.java:536)