贾斯珀报告JAVA摇摆

Question

I am trying to create a report using java swing that is able to print the data that I have on my SQL database, I found this after I googled my problem and I follow the step-by-step tutorial, everything goes smooth and no error occured, at first it seems fine but after I put these codes (that will generate the report that I want) :

public void reportviewer() {
            try{
            String report = "C:\\Users\\cleanfuel\\Documents\\NetBeansProjects\\StringManipulation\\src\\stringmanipulation\\report1.jrxml";
            JasperReport jasp_report = JasperCompileManager.compileReport(report);
            JasperPrint jasp_print = JasperFillManager.fillReport(jasp_report, null, con);
            JasperViewer.viewReport(jasp_print);
            }
            catch (Exception e) {System.out.print(e);}
        }enter code here

After I run the program and clicking the buttong report, an error occured and print this :

Can anyone tell me how to fix this one? Did my I miss something?

Answer 1

Just create a log4j.properties and put it in your classpath:

#
# connector logging configuration
#
# From most to least verbose: TRACE, DEBUG, INFO, WARN, ERROR, OFF
log4j.rootCategory=INFO, stdout

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%p [%c{1}] - %m%n

Answer 2

Basically it's just log4j complaining that there are no appenders for it to output it's output to.

Unless you are really concerned about the output from Jasper Reports code, you don't need to worry about it to much.

If you want a quick fix, you could add the following to you code before you execute anything else.

PatternLayout pl = new PatternLayout("[%-5p] %C.%M:%L: %m%n");
ConsoleAppender appender = new ConsoleAppender(pl);
Logger.getRootLogger().addAppender(appender);

It will basically add a console appender that will send the output to the console.

Take a look at log4j for more details.

Updated with example

import org.apache.log4j.ConsoleAppender;
import org.apache.log4j.Logger;
import org.apache.log4j.PatternLayout;

public class Test {

    public static void main(String[] args) {
        PatternLayout pl = new PatternLayout("[%-5p] %C.%M:%L: %m%n");
        ConsoleAppender appender = new ConsoleAppender(pl);
        Logger.getRootLogger().addAppender(appender);
        // The rest of your code...
    }
}