遇到问题，求高手相助！非常感谢！
大家好！我写了一个连接数据库的类，然后在servlet类中实例化一个对象，然后对数据库进行操作！然而报错，提示如下：
2011-4-6 16:44:32 org.apache.catalina.startup.HostConfig checkResources
信息: Reloading context [/DownLoad1.0]
com.mysql.jdbc.exceptions. Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:407)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1116)
at com.mysql.jdbc.MysqlIO.readPacket(MysqlIO.java:690)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1093)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2338)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2371)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2163)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:794)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:407)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:378)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:185)
at com.bean.Dao.open(Dao.java:21)
at com.control.Logic.service(Logic.java:20)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:864)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:579)
at org.apache.tomcat.(AprEndpoint.java:1665)
at java.lang.Thread.run(Thread.java:619)
Caused by: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2539)
at com.mysql.jdbc.MysqlIO.readPacket(MysqlIO.java:614)
... 30 more
望高手给予指点！
非常感谢！
程序代码如下：Dao.java
package com.bean;
import java.sql.*;
public class Dao {
private String user;
private String password;
private String url;
private Statement stmt;
private Connection conn;
public Dao()
{
url="jdbc:mysql://localhost:8080/phone?characterEncoding=UTF-8";
user="root";
password="123";
}
public void open() throws ClassNotFoundException, SQLException
{
Class.forName("com.mysql.jdbc.Driver");
conn=DriverManager.getConnection(url,user,password);
stmt=conn.createStatement();
}
public void insert(String sql) throws SQLException
{
stmt.execute(sql);
}
public void close() throws SQLException
{
if(stmt!=null)
stmt.close();
if(conn!=null)
conn.close();
}
}
logic.java代码：
package com.control;
import com.bean.Dao;
import com.bean.Websit;
import
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class Logic extends HttpServlet {
private Dao dao=new Dao();
public void init() throws ServletException {
try {
dao.open();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
protected void service(HttpServletRequest request,HttpServletResponse response)throws ServletException,IOException
{
}
public void destroy() {
try {
dao.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
