用Eclipse连接MySql的连接问题
[code=Java][/code]
package util;
import java.sql.*;
import java.sql.Connection;
public class Certificate {
private String username;
private String password;
public Certificate()
{
}
public void cert()
{
try {
Class.forName("com.mysql.jdbc.Driver");
System.out.println("加载成功");
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
System.out.print("驱动加载失败!");
e.printStackTrace();
}
try {
Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/goahead","root","admin");
System.out.println("数据库连接成功!");
Statement statement = connection.createStatement();
ResultSet rs = statement.executeQuery("select * from credentials");
while(rs.next())
{
System.out.println(rs.getString("username"));
System.out.println(rs.getString("password"));
username = rs.getString("username");
password = rs.getString("password");
}
} catch (SQLException e) {
// TODO Auto-generated catch block
System.out.print("获取信息出错!");
e.printStackTrace();
}
}
public String getUserName()
{
return username;
}
public String getPassWord()
{
return password;
}
//
//public static void main(String[] args)
//{
//Certificate cert = new Certificate();
//cert.cert();
//}
}
这个是我用来连接mysql的代码，我直接在这个类做测试的时候，连接mysql很快只需要0.几秒。
但是当我启动webserver(tomcat)后，在servlet里面调用这个类来进行连接的时候，就很慢了，需要10多秒，而且打了很多的
log（trace）信息,如下：
Mon Aug 20 20:44:43 CST 2012 TRACE: --> MysqlIO.java:1939 com.mysql.jdbc.MysqlIO.versionMeetsMinimum(4, 1, 0)
Mon Aug 20 20:44:43 CST 2012 TRACE: --> MysqlIO.java:997 com.mysql.jdbc.MysqlIO.getServerMajorVersion()
Mon Aug 20 20:44:43 CST 2012 TRACE: <-- MysqlIO.java:997 com.mysql.jdbc.MysqlIO.getServerMajorVersion(..) returning 5
Mon Aug 20 20:44:43 CST 2012 TRACE: --> MysqlIO.java:997 com.mysql.jdbc.MysqlIO.getServerMajorVersion()
Mon Aug 20 20:44:43 CST 2012 TRACE: <-- MysqlIO.java:997 com.mysql.jdbc.MysqlIO.getServerMajorVersion(..) returning 5
Mon Aug 20 20:44:43 CST 2012 TRACE: <-- MysqlIO.java:1939 com.mysql.jdbc.MysqlIO.versionMeetsMinimum(..) returning true
Mon Aug 20 20:44:43 CST 2012 TRACE: <-- Connection.java:5895 com.mysql.jdbc.Connection.versionMeetsMinimum(..) returning true
Mon Aug 20 20:44:43 CST 2012 TRACE: --> Field.java:794 com.mysql.jdbc.Field.isUnsigned()
Mon Aug 20 20:44:43 CST 2012 TRACE: <-- Field.java:794 com.mysql.jdbc.Field.isUnsigned(..) returning false
Mon Aug 20 20:44:43 CST 2012 TRACE: --> Field.java:861 com.mysql.jdbc.Field.toString()
Mon Aug 20 20:44:43 CST 2012 TRACE: --> Field.java:409 com.mysql.jdbc.Field.getDatabaseName()
Mon Aug 20 20:44:43 CST 2012 TRACE: --> Field.java:582 com.mysql.jdbc.Field.getStringFromBytes(5, 7)
麻烦各位帮忙看下这个是什么问题呢？
谢谢
[解决办法]
把在servlet进行连接的代码粘出来看看。
一般情况下应该不会打出那些日志的，主动调用的时候才会输出那些日志，或者项目里有多个mysql驱动包，楼主检查下lib目录，也检查下tomcat的lib目录，看是不是有多个驱动包？
[解决办法]
看你日志，好像是自动匹配驱动啊
[解决办法]
1、连接没有正常的关闭,resultset,statemate,connection,这样会耗资源越来越慢
2、每次操作都重新建立连接,比较耗时
