Ubuntu 上 Tomcat 6 和 MySQL 5.x 连接错误

Question

当尝试连接到 Tomcat 6 上运行的 JSP Web 应用程序中的 MySQL 5.x 数据库时，我收到以下异常：

org.apache.jasper.JasperException: javax.servlet.ServletException: com.mysql.jdbc.CommunicationsException: Communications link failure due to underlying exception: 

** BEGIN NESTED EXCEPTION ** 

java.net.SocketException
MESSAGE: java.security.AccessControlException: access denied (java.net.SocketPermission [0:0:0:0:0:0:0:1]:3307 connect,resolve)

STACKTRACE:

java.net.SocketException: java.security.AccessControlException: access denied (java.net.SocketPermission [0:0:0:0:0:0:0:1]:3307 connect,resolve)
    at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:151)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:280)
    at com.mysql.jdbc.Connection.createNewIO(Connection.java:1699)
    at com.mysql.jdbc.Connection.<init>(Connection.java:405)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:268)
    at java.sql.DriverManager.getConnection(DriverManager.java:620)
    at java.sql.DriverManager.getConnection(DriverManager.java:200)
    at org.apache.jsp.doLogin_jsp._jspService(doLogin_jsp.java:70)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at sun.reflect.GeneratedMethodAccessor32.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:616)
    at org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:244)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAsPrivileged(Subject.java:537)
    at org.apache.catalina.security.SecurityUtil.execute(SecurityUtil.java:276)
    at org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:162)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:283)
    at org.apache.catalina.core.ApplicationFilterChain.access$000(ApplicationFilterChain.java:56)
    at org.apache.catalina.core.ApplicationFilterChain$1.run(ApplicationFilterChain.java:189)
    at java.security.AccessController.doPrivileged(Native Method)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:185)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
    at java.lang.Thread.run(Thread.java:636)

可能是什么原因以及如何修复它？

Answer 1

这是跟踪的相关部分：

java.net.SocketException 消息：java.security.AccessControlException：访问被拒绝（java.net.SocketPermission [0:0:0:0:0:0:0:1]:3307 连接，解析）

Web应用程序没有连接/解析提到的套接字的权限。您需要在 Tomcat 级别进行配置。打开 /conf/catalina.policy 并添加以下代码块：

grant {
    permission java.net.SocketPermission "localhost:3307", "connect,resolve";
};

如果您想要更多限制，例如仅授予对 /lib 中存在的特定 JDBC 驱动程序的访问权限/filename.jar，然后添加以下内容：

grant codeBase "jar:file:${catalina.home}/lib/filename.jar!/-" {
    permission java.net.SocketPermission "localhost:3307", "connect,resolve";
};

---

与具体问题无关，以下几行

at java.sql.DriverManager.getConnection(DriverManager.java:200)
at org.apache.jsp.doLogin_jsp._jspService(doLogin_jsp.java:70)

表明您正在 JSP 文件内连接数据库。也许您刚刚开始学习，但我只想提一下，这不是最佳实践。数据库连接应该在它自己的类中完成，您又在 servlet 类中使用这些类，servlet 类又转发到 JSP，JSP 又显示结果。通过 URL 调用 servlet 应该会产生相同的结果，但最终会得到更好的可重用和可维护的代码。