如何在log4j中以编程方式指定RollingFileAppender的文件名？

Question

Background:

My application allows two operating modes that can be chosen from a GUI.
If it operates as a server, I want to direct the logs into the server.log file.
If it operates as a client, I want to direct the logs into the client.log file.

Question:

How to programmingly specify different names for different modes for RollingFileAppender in log4j?

Added (10-29-2014): The current answer by @Manish Maheshwari does not work for me. It raises the warning log4j:WARN File option not set for appender [file] and it does not write logs into file.

---

My attempt:

I define RoleSpecificRollingFileAppender class which extends RollingFileAppender and overrides the setFile() method.

public class RoleSpecificRollingFileAppender extends RollingFileAppender {
    @Override
    public void  setFile(String fileName) {
        super.setFile(fileName);
    }
}

My RollingFileAppender is as follows:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE log4j:configuration PUBLIC "-//LOGGER" "http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/xml/doc-files/log4j.dtd">

<log4j:configuration>
    # Root logger option
    log4j.rootLogger=INFO, file

    # Direct log messages to a log file
    log4j.appender.file=[[What to do here? org.apache.log4j.RollingFileAppender]]
    log4j.appender.file.File = [[I don't know how to do here.]]
    log4j.appender.file.MaxFileSize=50MB
    log4j.appender.file.MaxBackupIndex=10
    log4j.appender.file.layout=org.apache.log4j.PatternLayout
    log4j.appender.file.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm} %-5p %c{1}:%L - %m%n
</log4j:configuration>

However I don't know what to do in Java code and the log4j.properties file.

Answer 1

Use the fully qualified classname for RoleSpecificRollingFileAppender in log4j.appender.file property. Try removing the File line from config.

Use this at bootstrap:

RollingFileAppender app = new RoleSpecificRollingFileAppender();
app.setFile(myfile);
BasicConfigurator.configure(app);