Tomcat6无法连接MySql（驱动没有收到服务器发来的任何数据包）

Question

我正在使用 Ubuntu 9.10 作为操作系统在本地计算机上运行 Apache Tomcat 6.0.20 / MySQL 5.1.37-lubuntu / sun-java6-jdk /sun-java6-jre / sun-java6-bin 。 我正在尝试让一个简单的数据库查询示例运行 2 天，但我仍然收到此异常：

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 如下所示：

<?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>

• read很多论坛条目/尝试了很多不同的设置（当它不起作用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
• 未设置跳过网络标志对于数据库（已设置 BIND 127.0.0.1）
• 防火墙已关闭（sudo ufw disable）
• MySQL 可以工作（使用此 skript 中使用的用户进行了多次测试）

• telnet localhost 3306 说

  正在尝试::1... 正在尝试 127.0.0.1... 连接到本地主机。 转义字符是“^]”。 连接被外部主机关闭。

---

TestConnection.java 产生以下输出：

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驱动程序连接到DB的方式和Perl DBI模块之间是否有区别，但是这个PERL skript

#!/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，我在重新启动 tomcat 时发现了此消息，不知道它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。出现这个错误的原因是tomcat的安全限制。

您必须将以下行添加到您的 $TOMCAT-CONFIG/policy.d/04webapps.policy

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

对我有用，希望它也对您有用:)

Answer 2

我有同样的问题。

事实证明，我通过运行三个 mysqld 实例搞乱了服务器，所以杀死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：

1. 端口号必须仅为 3306

2. 如果使用 Tomcat6，请在 lib 中添加 mysql.jar

   >

Answer 4

请尝试使用由 MySQL 分发的“官方”Connector/J 5.1，而不是deb（请注意，我并不反对 deb）。

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