1. CS520 Web Programming Bits and Pieces of Web Programming (I) Chengyu Sun California State University, Los Angeles

2. Roadmap Logging Testing View Template Framework Exception Handling

3. Logging Use print statements to assist debugging Why do we want to do that when we have GUI debugger?? public void foo() { System.out.println( “loop started” ); // some code that might get into infinite loop … System.out.println( “loop finished” ); }

4. Requirements of Good Logging Tools Minimize performance penalty Support different log output Console, file, database, … Support different message levels Fatal, error, warn, info, debug, trace Easy configuration

5. Java Logging Libraries Logging implementations Log4j - http://logging.apache.org/log4j/http://logging.apache.org/log4j/ java.util.logging in JDK Logging API Apache Commons Logging (JCL) - http://commons.apache.org/logging/ http://commons.apache.org/logging/ Simple Logging Façade for Java (SLF4J) - http://www.slf4j.org/ http://www.slf4j.org/

6. Choose Your Logging Libraries Log4j Widely used Good performance Easy configuration java.util.logging Part of JDK, i.e. no extra library dependency Commons Logging Determines logging implementation at runtime SLF4j Statically linked to a logging implementation  Cleaner design  Better performance  Less problem

7. Using Log4j and SLF4j Library dependencies Coding Creating a Logger Logging statements Configuration Output format

8. Log4j Configuration File log4j.xml or log4j.properties Appender Output type Output format Logger Package or class selection Message level

9. Log4j PatternLayout http://logging.apache.org/log4j/1.2/api docs/org/apache/log4j/PatternLayout.ht ml

10. Logging in CSNS2 src/main/resources/log4j.xml build.properties app.log.dir app.log.level Use of Log Viewer plugin in Eclipse

11. Java Testing Frameworks JUnit http://www.junit.org/ Widely used and supported TestNG http://testng.org/ Technically superior to JUnit (for a while) but not as widely used or supported

12. What We Want From a Testing Framework Automation Including setup and tear-down Grouping and selection Test Dependency Skip tests that depend on tests that already failed Run independent test in parallel Report Other, e.g. tool support, API, dependency injection, and so on

13. Maven Support for JUnit/TestNG Library dependency Directory structure src/test/java src/test/resources The surefire plugin

14. Basic TestNG Annotations @Test Method Class Annotations for various before/after methods http://testng.org/doc/documentation-main.html#annotations

15. Group and Dependency @Test groups dependsOnMethods dependsOnGroups

16. Test Suite A test suite is represented by an XML file and contains one or more tests. Select tests by method, class, package, and group Include and exclude

17. Test Suite Example testng.xml

18. TestNG in CSNS2 Configuration Test classes inherit from Spring TestNG support classes @ContextConfiguration BeforeSuite and AfterSuite methods

19. More About TestNG TestNG Documenation – http://testng.org/doc/documentation- main.html http://testng.org/doc/documentation- main.html Next Generation Java Testing by Cédric Beust and Hani Suleiman

20. Apache Tiles http://tiles.apache.org/ A template framework for JSP Similar to Master Page and Razor in ASP.NET

21. The Need for View Templates Header Footer Content 1 Header Footer Content N page1.jsppageN.jsp

22. Why JSP Is Not Enough It breaks HTML syntax, e.g. in header.jsp and in footer.jsp. It’s difficult to create and manage multiple complex templates.

23. Basic Tiles Usage Template page = JSP + placeholders (i.e. attributes), Content: JSP, string, other tiles Definition: combine template and content Tiles Tag Library http://tiles.apache.org/framework/tiles-jsp/tlddoc/index.html

24. A Tiles Example Header Footer Content 1 Header Footer Content 2 page1.jsppage2.jsp

25. Tiles – Template Page Header Footer template.jsp

26. Tiles – Content Pages Content 1Content 2 page1.jsppage2.jsp

27. Tiles – Definitions

28. Resolve Tiles Views in Spring /WEB-INF/tiles.xml

29. Tiles Usage in CSNS2 WEB-INF/layout for template and header/footer pages WEB-INF/content for content pages WEB-INF/tiles.xml for definitions

30. Problem with Java Exceptions Too many checked exceptions Checked vs. Runtime exceptions Require lots of boilerplate exception handling code

31. Spring’s Solution to the Exception Problem Use primarily runtime exceptions Separate exception handling code into exception handlers

32. Controller Exception Handing in Spring An Exception Resolver handles all runtime exceptions thrown by controllers SimpleMappingExceptionResolverSimpleMappingExceptionResolver maps different exceptions to different views

33. ExceptionResolver in CSNS2 <bean id="exceptionResolver“ class="csns.web.resolver.ExceptionResolver"> exception/access exception/mail A SimpleMappingExceptionResolver with additional loggin.