编译数据库连接池出错，不知什么原因，请大家帮忙看看，谢谢发，急！！

Question

你仔细看看是不是在DBConnectionManager中少了一个大括号。

Answer 1

这是你反编译的吧，DBConnectionManager的源代码呢，对照一下改改。

Answer 2

DBConnectionManager里面有些内部类，调用需要改改。

Answer 3

To: stonegump(龙飞虎)    对啊，我这个是反编译的，DBConnectionManager编译通过，下面的代码，你帮帮忙怎么改。package myshop;import java.io.*;
import java.sql.*;
import java.util.*;public class DBConnectionManager
{
    class DBConnectionPool
    {        private int checkedOut;
        private Vector freeConnections;
        private int maxConn;
        private String name;
        private String password;
        private String URL;
        private String user;        public synchronized void freeConnection(Connection connection)
        {
            freeConnections.addElement(connection);
            checkedOut--;
            notifyAll();
        }        public synchronized Connection getConnection()
        {
            Connection connection = null;
            if(freeConnections.size() > 0)
            {
                connection = (Connection)freeConnections.firstElement();
                freeConnections.removeElementAt(0);
                try
                {
                    if(connection.isClosed())
                    {
                        log("从连接池" + name + "删除一个无效连接");
                        connection = getConnection();
                    }
                }
                catch(SQLException _ex)
                {
                    log("从连接池" + name + "删除一个无效连接");
                    connection = getConnection();
                }
            } else
            if(maxConn == 0 || checkedOut < maxConn)
                connection = newConnection();
            if(connection != null)
                checkedOut++;
            return connection;
        }        public synchronized Connection getConnection(long l)
        {
            long l1 = (new Date()).getTime();
            Connection connection;
            while((connection = getConnection()) == null) 
            {
                try
                {
                    wait(l);
                }
                catch(InterruptedException _ex) { }
                if((new Date()).getTime() - l1 >= l)
                    return null;
            }
            return connection;
        }        private Connection newConnection()
        {
            Connection connection = null;
            try
            {
                if(user == null)
                    connection = DriverManager.getConnection(URL);
                else
                    connection = DriverManager.getConnection(URL, user, password);
                log("连接池" + name + "创建一个新的连接");
            }
            catch(SQLException sqlexception)
            {
                log(sqlexception, "无法创建下列URL的连接: " + URL);
                return null;
            }
            return connection;
        }        public synchronized void release()
        {
            for(Enumeration enumeration = freeConnections.elements(); enumeration.hasMoreElements();)
            {
                Connection connection = (Connection)enumeration.nextElement();
                try
                {
                    connection.close();
                    log("关闭连接池" + name + "中的一个连接");
                }
                catch(SQLException sqlexception)
                {
                    log(sqlexception, "无法关闭连接池" + name + "中的连接");
                }
            }            freeConnections.removeAllElements();
        }

Answer 4

接上：       public DBConnectionPool(String s, String s1, String s2, String s3, int i)
        {
            freeConnections = new Vector();
            name = s;
            URL = s1;
            user = s2;
            password = s3;
            maxConn = i;
        }
    }
    private static DBConnectionManager instance;
    private static int clients;
    private Vector drivers;
    private PrintWriter log;
    private Hashtable pools;    private DBConnectionManager()
    {
        drivers = new Vector();
        pools = new Hashtable();
        init();
    }    private void createPools(Properties properties)
    {
        for(Enumeration enumeration = properties.propertyNames(); enumeration.hasMoreElements();)
        {
            String s = (String)enumeration.nextElement();
            if(s.endsWith(".url"))
            {
                String s1 = s.substring(0, s.lastIndexOf("."));
                String s2 = properties.getProperty(s1 + ".url");
                if(s2 == null)
                {
                    log("没有为连接池" + s1 + "指定URL");
                } else
                {
                    String s3 = properties.getProperty(s1 + ".user");
                    String s4 = properties.getProperty(s1 + ".password");
                    String s5 = properties.getProperty(s1 + ".maxconn", "0");
                    int i;
                    try
                    {
                        i = Integer.valueOf(s5).intValue();
                    }
                    catch(NumberFormatException _ex)
                    {
                        log("错误的最大连接数限制: " + s5 + " .连接池: " + s1);
                        i = 0;
                    }
                    DBConnectionPool dbconnectionpool = new DBConnectionPool(s1, s2, s3, s4, i);
                    pools.put(s1, dbconnectionpool);
                    log("成功创建连接池" + s1);
                }
            }
        }    }    public void freeConnection(String s, Connection connection)
    {
        DBConnectionPool dbconnectionpool = (DBConnectionPool)pools.get(s);
        if(dbconnectionpool != null)
            dbconnectionpool.freeConnection(connection);
    }    public Connection getConnection(String s)
    {
        DBConnectionPool dbconnectionpool = (DBConnectionPool)pools.get(s);
        if(dbconnectionpool != null)
            return dbconnectionpool.getConnection();
        else
            return null;
    }    public Connection getConnection(String s, long l)
    {
        DBConnectionPool dbconnectionpool = (DBConnectionPool)pools.get(s);
        if(dbconnectionpool != null)
            return dbconnectionpool.getConnection(l);
        else
            return null;
    }    public static synchronized DBConnectionManager getInstance()
    {
        if(instance == null)
            instance = new DBConnectionManager();
        clients++;
        return instance;
    }    private void init()
    {
        java.io.InputStream inputstream = getClass().getResourceAsStream("db.properties");
        Properties properties = new Properties();
        try
        {
            properties.load(inputstream);
        }
        catch(Exception _ex)
        {
            System.err.println("不能读取属性文件. 请确保db.properties在CLASSPATH指定的路径中");
            return;
        }
        String s = properties.getProperty("logfile", "DBConnectionManager.log");
        try
        {
            log = new PrintWriter(new FileWriter(s, true), true);
        }
        catch(IOException _ex)
        {
            System.err.println("无法打开日志文件: " + s);
            log = new PrintWriter(System.err);
        }
        loadDrivers(properties);
        createPools(properties);
    }    private void loadDrivers(Properties properties)
    {
        String s = properties.getProperty("drivers");
        for(StringTokenizer stringtokenizer = new StringTokenizer(s); stringtokenizer.hasMoreElements();)
        {
            String s1 = stringtokenizer.nextToken().trim();
            try
            {
                Driver driver = (Driver)Class.forName(s1).newInstance();
                DriverManager.registerDriver(driver);
                drivers.addElement(driver);
                log("成功注册JDBC驱动程序" + s1);
            }
            catch(Exception exception)
            {
                log("无法注册JDBC驱动程序: " + s1 + ", 错误: " + exception);
            }
        }    }    private void log(String s)
    {
        log.println(String.valueOf(new Date()) + ": " + s);
    }    private void log(Throwable throwable, String s)
    {
        log.println(String.valueOf(new Date()) + ": " + s);
        throwable.printStackTrace(log);
    }    public synchronized void release()
    {
        if(--clients != 0)
            return;
        DBConnectionPool dbconnectionpool;
        for(Enumeration enumeration = pools.elements(); enumeration.hasMoreElements(); dbconnectionpool.release())
            dbconnectionpool = (DBConnectionPool)enumeration.nextElement();        for(Enumeration enumeration1 = drivers.elements(); enumeration1.hasMoreElements();)
        {
            Driver driver = (Driver)enumeration1.nextElement();
            try
            {
                DriverManager.deregisterDriver(driver);
                log("撤销JDBC驱动程序 " + driver.getClass().getName() + "的注册");
            }
            catch(SQLException sqlexception)
            {
                log(sqlexception, "无法撤销下列JDBC驱动程序的注册: " + driver.getClass().getName());
            }
        }    }
}

Answer 5

我编译过了没有你说的错误。但是需要指明Date()是属于哪个包的。
导入文件该为：
import java.io.*;
import java.sql.*;
import java.util.Date;
import java.util.Vector;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Properties;
import java.util.StringTokenizer;

Answer 6

To: little0416(天涯海角)    我是第一贴子那个代码有错误。

Answer 7

我看过代码了。
DBConnectionManager.access$0(DBConnectionManager.this, "关闭连接池" + name + "中的一个连接");
实际上是想调用DBConnectionManager的log方法，而log方法在DBConnectionManager中声明为private.
由于出错代码只是起记录日志的作用。所以可以把它们全注释掉。或者，要保留日志，按照下面的方法修改一下即可。
我不贴修改后的代码，太长。你照这个改一下就行：
DBConnectionManager：
将            private PrintWriter log;
改为            private static PrintWriter log;
将            private void log(String s)
            {
                log.println(String.valueOf(new Date()) + ": " + s);
            }            private void log(Throwable throwable, String s)
            {
                log.println(String.valueOf(new Date()) + ": " + s);
                throwable.printStackTrace(log);
            }
改为            public static void log(String s)
            {
                log.println(String.valueOf(new Date()) + ": " + s);
            }            public static void log(Throwable throwable, String s)
            {
                log.println(String.valueOf(new Date()) + ": " + s);
                throwable.printStackTrace(log);
            }DBConnectionPool：
将            try
            {
                connection.close();
                DBConnectionManager.access$0(DBConnectionManager.this, "关闭连接池" + name + "中的一个连接");//放此处没用
            }
            catch(SQLException sqlexception)
            {
                DBConnectionManager.access$1(DBConnectionManager.this, sqlexception, "无法关闭连接池" + name + "中的连接");
          }
改为  
            try
            {
                if(connection.isClosed())
                {
                    connection = getConnection();
                }
            }
            catch(SQLException _ex)
            {
                DBConnectionManager.log(_ex, "从连接池" + name + "删除一个无效连接");
                connection = getConnection();
            }修改都是类似的，相信你很容易搞定。