Question

我在本地计算机上使用Ubuntu 9.10作为操作系统运行Apache Tomcat 6.0.20 / MySQL 5.1.37-lubuntu / sun-java6-jdk / sun-java6-jre / sun-java6-bin。我正试图让一个简单的数据库查询示例现在运行2天，但我仍然得到这个例外：

org.apache.jasper.JasperException: javax.servlet.ServletException: javax.servlet.jsp.JspException: Unable to get connection, DataSource invalid: "org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (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.)"
 org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:522)
 org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:398)
 org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
 org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

root cause

javax.servlet.ServletException: javax.servlet.jsp.JspException: Unable to get connection, DataSource invalid: "org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (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.)"
 org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:862)
 org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:791)
 org.apache.jsp.index_jsp._jspService(index_jsp.java:104)
 org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
 org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
 org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
 org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

root cause

javax.servlet.jsp.JspException: Unable to get connection, DataSource invalid: "org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (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.)"
 org.apache.taglibs.standard.tag.common.sql.QueryTagSupport.getConnection(QueryTagSupport.java:285)
 org.apache.taglibs.standard.tag.common.sql.QueryTagSupport.doStartTag(QueryTagSupport.java:168)
 org.apache.jsp.index_jsp._jspx_meth_sql_005fquery_005f0(index_jsp.java:274)
 org.apache.jsp.index_jsp._jspx_meth_c_005fotherwise_005f0(index_jsp.java:216)
 org.apache.jsp.index_jsp._jspx_meth_c_005fchoose_005f0(index_jsp.java:130)
 org.apache.jsp.index_jsp._jspService(index_jsp.java:93)
 org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
 org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
 org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
 org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

我的web.xml看起来像这样：

<?xml version="1.0" encoding="utf-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    version="2.5">
  <resource-ref>
      <description>DB Connection</description>
      <res-ref-name>jdbc/testDB</res-ref-name>
      <res-type>javax.sql.DataSource</res-type>
      <res-auth>Container</res-auth>
  </resource-ref>
</web-app>

context.xml如下所示：

<?xml version="1.0" encoding="UTF-8"?>
<Context path="/my1stApp" docBase="/var/www/jsp/my1stApp" debug="5" reloadable="true" crossContext="true">
    <Resource name="jdbc/testDB" auth="Container" type="javax.sql.DataSource"
    maxActive="5" maxIdle="5" maxWait="10000"
    username="user" password="password" driverClassName="com.mysql.jdbc.Driver"
    url="jdbc:mysql://localhost:3306/some"/>
</Context>

，jsp文件如下所示：

<%@ page contentType="text/html" %>

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>

<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<%@ taglib prefix="sql" uri="http://java.sun.com/jsp/jstl/sql" %>


<html>

  <head>

    <title>DroneLootTool</title>

  </head>

  <body bgcolor="white">



 <sql:query var="res" dataSource="jdbc/testDB">
  select name, othername 
  from mytable
 </sql:query>

  <h2>Results</h2>

<c:forEach var="row" items="${res.rows}">
    Name ${row.name}<br/>
    MoreName ${row.othername}<br/><br/>
</c:forEach>


  </body>

</html>

阅读了大量论坛条目/尝试了很多不同的设置（当它没有工作时总是改回原始设置）
在/ etc / default / tomcat6中设置TOMCAT6_SECURITY = no，因为TOMCAT6_SECURITY = yes也造成了麻烦
没有为DB设置skip-networking标志（BIND 127.0.0.1已设置）
防火墙被关闭（sudo ufw disable）
MySQL的工作原理（在此skript中用过的用户多次测试）
telnet localhost 3306说

尝试:: 1 ... 试试127.0.0.1 ...... 连接到localhost。逃脱角色是'^]'。连接由外国主机关闭。

TestConnection.java产生了以下输出：

me @ my-laptop：〜/ Desktop $ java -classpath'/usr/share/java/mysql.jar：。/'TestConnection com.mysql.jdbc.Driver jdbc：mysql：// localhost：3306 / testDB myuser mypassword

com.mysql.jdbc.CommunicationsException: Communications link failure
    Last packet sent to the server was 0 ms ago.
        at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1070)
        at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2103)
        at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:718)
        at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:298)
        at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:282)
        at java.sql.DriverManager.getConnection(DriverManager.java:582)
        at java.sql.DriverManager.getConnection(DriverManager.java:185)
        at TestConnection.checkConnection(TestConnection.java:40)
        at TestConnection.main(TestConnection.java:21)
    Caused by: com.mysql.jdbc.CommunicationsException: Communications link failure

    Last packet sent to the server was 0 ms ago.
        at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1070)
        at com.mysql.jdbc.MysqlIO.readPacket(MysqlIO.java:666)
        at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1069)
        at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2031)
        ... 7 more
    Caused by: java.io.EOFException: 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:2431)
        at com.mysql.jdbc.MysqlIO.readPacket(MysqlIO.java:590)
        ... 9 more
    Connection failed.

我不知道java驱动程序连接数据库和Perl DBI模块的方式是否存在差异，但此PERL skript是否正常工作

#!/usr/bin/perl -w 

use CGI;
use DBI;
use strict;

print CGI::header();

my $dbh = DBI->connect("dbi:mysql:some:localhost", "user", "password");

my $sSql = "SELECT * from mytable";

my $ppl = $dbh->selectall_arrayref( $sSql );

foreach my $pl (@$ppl)
{
  my @array = @$pl;
  print @array;
}

$dbh->disconnect;

在mysql上启用了--log-warnings，但我没有收到任何新的警告。当我在日志中搜索警告时，我在重启tomcat时发现了这条消息，不知道是否有助于找到问题：

Feb  2 19:50:37 tobias-laptop jsvc.exec[3129]: 02.02.2010 19:50:37 org.apache.catalina.startup.HostConfig checkResources#012INFO: Undeploying context [/myapp]
Feb  2 19:50:37 tobias-laptop jsvc.exec[3129]: 02.02.2010 19:50:37 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads#012SCHWERWIEGEND: A web application appears to have started a thread named [MySQL Statement Cancellation Timer] but has failed to stop it. This is very likely to create a memory leak.
Feb  2 19:50:37 tobias-laptop jsvc.exec[3129]: 02.02.2010 19:50:37 org.apache.catalina.startup.HostConfig deployDescriptor#012INFO: Deploying configuration descriptor myapp.xml

Answer 1

我解决了这个问题。发生此错误的原因是tomcat安全限制。

您必须在$TOMCAT-CONFIG/policy.d/04webapps.policy

中添加以下行

permission java.net.SocketPermission "127.0.0.1:3306", "connect";

适合我，希望它也适合你：）

Answer 2

我有同样的问题。

事实证明我通过运行三个mysqld实例搞砸了服务器，所以杀掉了不需要的解决了我的问题：

me@ubuntu:~$ ps aux | grep mysql
mysql     8149  0.1  0.4 280484 26008 ?        Ssl  13:24   0:00 /usr/sbin/mysqld
me     8256  0.0  0.0   4392   836 pts/3    S+   13:24   0:00 grep --color=auto mysql
root     26569  0.0  0.0   5952  1856 ?        S    10:44   0:00 sudo /usr/sbin/mysqld --skip-grant-tables --skip-networking
mysql    26570  0.1  0.6 323528 41936 ?        Sl   10:44   0:15 /usr/sbin/mysqld --skip-grant-tables --skip-networking

me@ubuntu:~$ sudo kill 26570

Answer 3

Class.forName("com.mysql.jdbc.Driver");
            con=DriverManager.getConnection("jdbc:mysql://localhost:3306/indiadb","root","root");

检查：

端口号必须只有3306
如果您使用的是Tomcat6，请在lib中添加mysql.jar

Answer 4

请尝试使用“官方”Connector/J 5.1，即由MySQL发布，而不是deb（注意我没有反对deb）。

另外请在mysql服务器上启用--log-warnings，看看错误日志中是否显示任何内容。

Tomcat6无法连接到MySql（驱动程序未收到来自服务器的任何数据包）

4 个答案: