13: Logging Your Actions in Java

Encoder QR Code in Java 13: Logging Your Actions

Documentation is also available at the site Log4J offers more logging options than the Java 14 logger, including where you write the files and how you format them Listing 13-1 shows a sample of a Log4J configuration file that outputs to the console and to a rolling log file

Listing 13-1

1 2 3 4 5 6 7 8 9 # # # #

The root category uses two appenders called stdout and R The root category assumes the INFO priority for root If the priority is not specified, it is DEBUG The root category is the only category that has a default priority

log4jrootCategory=INFO, stdout, R # stdout is set to be a ConsoleAppender which outputs to std out log4jappenderstdout=orgapachelog4jConsoleAppender # Configure stdout appender to use the PatternLayout log4jappenderstdoutlayout=orgapachelog4jPatternLayout

10 # Pattern to output the caller s filename and line number 11 log4jappenderstdoutlayoutconversionPattern =%d{DATE} %5p [%t] (%F:%L) %m%n 12 # R is the RollingFileAppender that outputs to a rolling log # file called rolling_log_filelog 13 log4jappenderR=orgapachelog4jDailyRollingFileAppender 14 log4jappenderRFile=${catalinabase}/logs/wp_log_filelog 15 log4jappenderRDatePattern= yyyy-MM-dd txt 16 # Define a pattern layout for the file 17 # For more information on conversion characters (ie d,p,t,c,l,m,n) 18 # please see the PatternLayout class of the Log4j API 19 log4jappenderRlayout=orgapachelog4jPatternLayout 20 log4jappenderRlayoutconversionPattern =%d{DATE} %5p [%t] (%F:%L) - %m%n

In Listing 13-1, note the following lines: Line 5: Specifies the priority of INFO using two appenders, stdout and R, which are defined later Line 7: Specifies that ConsoleAppender be used with stdout This means all messages will be written to the system console Lines 9 and 11: Specify the format to use when writing out messages to

Lines 13 15: Define the R appender as DailyRollingLogAppender This means that for each 24-hour period, a new file will be created and the old one closed You specify the file name and location, as well as the suffix that you want to append to the file after it has been rolled over In this case, the suffix is the date followed by the txt extension (such as 2003-11-27txt) Lines 19 20: Specify that the format for the R appender will be identical to the stdout appender The configuration of Log4J offers many options For detailed information on configuration issues, visit the Log4J Web site at jakartaapacheorg/log4j/ docs and review the documentation

14

Introducing the MusicCollection application Creating the database schema Configuring the data source Creating the pages Logging on Creating a user account Displaying albums Creating, editing, and deleting albums Logging off the program Handling exceptions in different ways Running the program

his chapter shows you how to create a complete application using Jakarta Struts To create this demonstration application you need to apply most of the concepts and techniques we have explored throughout the book You don t need to retype the code you can find the complete code for the MusicCollectioncom application at the Jakarta Struts For Dummies Web site at wwwdummiescom/go/jakarta

The hypothetical MusicCollectioncom application enables registered users to create and maintain a list of their favorite music In the application, we call each listing an album

The prospective user must join the Web site by entering a small amount of personal information, such as name, e-mail address, and a password Subsequent visits to the site require users to log on using their e-mail address and password After the user has logged on, the application retrieves a list of his or her albums from the database and displays this list The user may modify or delete an album or create one The application immediately updates all changes or additions in the database and displays the resulting album list When finished, users may log off to remove their connection to the system If an error should occur during the processing of a request, the application dis plays an appropriate error page Figure 14-1 shows the various pages and relationships that go to make up the application