Solve the problem of MySQL database under Linux

mysql| Solution | data | database | problem troubleshoot Linux under Tomcat connection MySQL database

Under Linux, developing a Web application that is always unsuccessful when calling a database, if you write a class individually and compile and execute access to the database, is normal, but use Web applications to tune this class to connect to the database. There will be an error: Com.mysql.jdbc.CommunicationsException:Communications link failure due to underlying exception:

* * BEGIN NESTED EXCEPTION * *

Java.security.AccessControlException
Message:access denied (java.net.SocketPermission localhost resolve)

StackTrace:

Java.security.AccessControlException:access denied (java.net.SocketPermission localhost resolve)

It seems that the error is not in the database and should be in the web-related place. All ports are checked, the discovery is open, and file permissions are open to other users. A search on the internet, some people say that is the problem of Java Security Configuration, change/usr/lib/jvm/java-1.5.0-sun-1.5.0.10/jre/lib/security/ The policy file under Java.policy, changed, still inaccessible, looks like the problem is not here, under the Tomcat folder, there are several policy files, in the/ETC/TOMCAT5.5/ POLICY.D, we should be able to see 5. Policy files, each with a different function, with annotations in them and inserting the following code in the appropriate place:

Grant CodeBase "file:/var/lib/tomcat5.5/webapps/Project name/-" {
Permission java.security.AllPermission;
};

This project will have the appropriate permissions, if it is not know which file should be placed under, then put a sentence in each file, it will certainly work.

In this way, Tomcat will open the Web application Access database permissions.