Working with PowerPoint Presentation using Java

The article shows how to work with PowerPoint presentation in Java using simple scripting language. Though open source from Apache POI supports working with PowerPoint presentations; but it has its own limitations.

Disadvantage  with Open source Apache POI-HSLF and POI-XLSF:

-         POI still in early development and is a subject
to incompatible changes in future.

-         Current version of POI (POI-HSLF and POI-XSLF)
supports only implementation of Powerpoint
2007 format.

-         HSLF and XSLF though has similar features, the
interface among them is not common; making maintenance difficult; if same
feature need to be provided in different format.

-         POI provides API  at very elementary level. For a task
as easy as copying a slide from one presentation to another presentation;
requires hundreds of lines of code and makes maintenance difficult.

-         We didn’t find even Jpeg conversions of powerpoint an easy task with POI.

A better option is use to the scripting provided by Microsoft itself and to use it within Java for powerpoint presentation. We have chosen to use vb script and run it using cscript (a command line version of wscript). One of the advantages with cscript over other types of programming is that for cscript,
everything you need is built into the Windows operating system. It is easy and doesn’t need any installation. Though it makes programming platform dependent; but it make sense; after all; we are going to use MSOffice on Windows machines only.

We would now take few examples of writing VB script for routine work required with powerpoint
presentations:

a)  Example of VB Script for copying a slide from one presentation to end of another presentation

Set pptDoc = CreateObject("PowerPoint.Application")

pptDoc.Visible = TRUE

Set objPresentation = pptDoc.Presentations.Open("D:\Workspace\vbscript\ppt\MyPresentationTo.pptx")

objPresentation.Slides.InsertFromFile _

"D:\Workspace\vbscript\ppt\MyPresentationFrom.pptx",objPresentation.Slides.Count , 1, 1

objPresentation.Save

objPresentation.close

pptDoc.Quit

Open method in above example opens presentation “MyPresentationTo.pptx” in which slide is
to be copied.  InsertFromFile method copies one slide from “MyPresentationFrom.pptx” at the end of
“MyPresentationTo.pptx”.

First argument of InsertFromFile specifies the name of presentation from which slides are to be copied. Second argument specifies the index after which you want to insert the copied slides in the opened presentation. Third argument specifies the index of first slide that you want to copy from presentation. Fourth argument specifies the index of last slide that you want to copy from presentation.

After copying slide; we saved the file and closed the presentation within script.

To try this; copy above example in a notepad; save it as “.vbs extention”
e.g. “CopySlide.vbs” and double click on it. Remember to create two ppt (MyPresentationTo.pptx, MyPresentationFrom.pptx) in the specified folder before executing script.

b)  Following example of VB Script shows how to add shapes to a slide:

Set pptDoc = CreateObject("PowerPoint.Application")

pptDoc.Visible = TRUE

Set objPresentation = pptDoc.Presentations.Open("D:\Workspace\vbscript\ppt\MyPresentationTo.pptx")

Set myDocument = objPresentation.Slides(1)

Set line = myDocument.Shapes.AddLine(40, 40, 80, 80)

objPresentation.Save

objPresentation.close

pptDoc.Quit

AddLine method  in above example adds a line to Slide 1 in above example.

c)  Following example shows how to export a presentation in jpg format:
    Set pptDoc = CreateObject("PowerPoint.Application")
    pptDoc.Visible = TRUE
   Set objPresentation = pptDoc.Presentations.Open 
    ("D:\Workspace\vbscript\ppt\MyPresentationTo.pptx")
   Set myDocument = objPresentation.Slides(1) myDocument.Export  
    "D:\Workspace\vbscript\ppt\MyPresentation.jpg","JPG"
    objPresentation.Save
   objPresentation.close
   pptDoc.Quit

Export command in above program exports presentation to jpg format. First argument to the method is the path where to export the file and second argument is the format in which presentation is to be exported.

Once you have learnt and played with scripts; you can write a small program to execute these scripts
from Java.

import java.io.IOException;

public class RunScript {
  public static void main (String args[]) throws IOException {

    if (args == null || args.length == 0) {

      System.out.println("Usage: java RunScript <scriptfile>" );

      System.exit(1);

    }

    runScript(args[0]);   
  }

  public static void runScript(String script) throws IOException {

    String command = "cmd /c cscript " + script;

    Runtime.getRuntime().exec(command);
  }

}

 

In above example you may call runScript method from any of your program.

 E.g. the script shown in example a) above was stored as “Copy Slide.vbs” and executed using following
command after compilation:

java RunScript  D:\Workspace\vbscript\scripts\CopySlide.vbs

It copied Slide 1 from  MyPresentationFrom.pptx at the end of MyPresentationFrom.pptx

The real power lies in making the script dynamic thru Java programming and then using it at runtime. Though this article has been focused on PowerPoint presentations; but you may use this technique with MSWord and MSExcel as well.

Advantage:

-         Provides code compatibility among various versions
of MSOffice

-         Easy to use commands

-         Tasks like copying slides and exporting can be
done within few lines of code.

Limitation:

-         Not compatible over platform

Audit Trail using log4j

Audit trail is used in most of the applications to track the activities performed by a user (e.g. resources accessed or changes made within the system). Audit trails of applications are generally stored in the database; as they require filtering based on different attributes like userid, date/time, activity etc. and sometime the logs are required to generate reports.

Traditional approach with in java application for audit trailing is to use jdbc. This approach is not only cumbersome but has few pitfalls. E.g. the audit feature cannot be switched off unless the application has been designed to do so. Similarly; a product may require different level of audit logs depending upon the environment where it is being implemented. E.g. an application deployed for guest user may not require auditing at all but same application if installed in a high secured zone may require very fine level of auditing.

With traditional approach of using jdbc; application can audit logs only in database. The application may require logging the audit trails to multiple locations (e.g. to file system/ console) apart from database.  While maintenance; it may even be required to know from which class the audit message has been generated. Traditionally a log (using log4j or java logging api) is written before/after making jdbc call to record audit in database. But it is at the mercy of developer if has written such code while auditing each log.

 Since most of the features mentioned above comes inherent with logging APIs such as log4j. It would be a good idea to use such logging API itself for auditing as well.

This article would use log4j for logging audit trail and mysql as database for storing them.

Let’s first define the information we want our application to capture for auditing purpose. Say we want to maintain audit id, user id, timestamp, audit level, activity and activity detail in our audit. We would create our audit table in the database using following sql statement:

CREATE TABLE AUDIT(

    AUDIT_ID INT PRIMARY KEY AUTO_INCREMENT,

    USER_ID VARCHAR(50),

    TIMESTAMP TIMESTAMP,

    LEVEL   VARCHAR(5),

    ACTIVITY VARCHAR(50),

    ACTIVITY_DETAIL VARCHAR(1000)

 );

Since AUDIT_ID is a auto generated column and information regarding TIMESTAMP and LEVEL can be provided log4j; hence our code needs not to take these columns into account. We only need to consider how to pass application level information like userid, activity and activity detail to logger.

It would be a good idea to create a wrapper over Logger that can take care of passing all the application level information like userid, activity etc. to logger.

Let’s create a class that would encapsulate logger and would act our one stop point for auditing.

package myapplication.audit;

import org.apache.log4j.Level;

import org.apache.log4j.Logger;

import org.apache.log4j.MDC;

public class AuditLogger {

      public static void debug (String userid, String activity,

String activityDetail) {

   …

}    

public static void info (String userid, String activity,

…

String activityDetail) {

               …

}

You may create other methods for different log levels. In case mutilple log levels are not required in your application; you may create single method with name audit.

We are going to use two features of Log4J: MDC and FQCN. Mapped diagnostic context (MDC) would be used to add additional information like user id and activity to the logs.

package myapplication.audit;

import org.apache.log4j.Level;

import org.apache.log4j.Logger;

import org.apache.log4j.MDC;

public class AuditLogger {

      

       private static String FQCN =  "myapplication.audit.AuditLogger";

      

       public static void info (String userid, String activity, String activityDetail) {

              MDC.put("userid", userid);

              MDC.put("activity", activity);

              Logger.getLogger(AuditLogger.class.getName()).log(FQCN, Level.INFO,  activityDetail, null);

              MDC.clear();

       }

       …

…

}

Please note we have shown a method with the name info() which logs audit trail with level INFO. We can have additional methods with others log levels as well.

Additional information like userid and activity has been passed by application to the logger using MDC. Once the information has been audited; the information has been later on cleared using clear() method of MDC.

We have configured JDBCAppender and configured database information along with SQL statement to insert audit trail in the database. Please note JDBCAppender doesn’t require PatternLayout.

xml version="1.0" encoding="UTF-8"?>

DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">

       <appender name="FILE" class="org.apache.log4j.RollingFileAppender">

              <param name="File" value="logs/audit.log">param>

              <param name="Append" value="true">param>

              <layout class="org.apache.log4j.PatternLayout">

                     <param name="ConversionPattern"

                           value="%d %-5p [%t] %C{3} (%F:%L) - %m%n">param>

              layout>

       appender>

      

       <appender name="DB" class="org.apache.log4j.jdbc.JDBCAppender">

              <param name="URL" value="jdbc:mysql://localhost/auditschema"/>

              <param name="driver" value="com.mysql.jdbc.Driver"/>

              <param name="user" value="root"/>

              <param name="password" value="admin"/>

              <param name="sql" value="INSERT INTO AUDIT(USER_ID, TIMESTAMP, LEVEL, ACTIVITY, ACTIVITY_DETAIL) VALUES('%X{userid}','%d{yyyy-MM-dd HH:mm:ss.SSS}','%p', '%X{activity}', '%m')"/>

      

       appender>

       <appender name="NULL" class="org.apache.log4j.varia.NullAppender">appender>

      

       <category  name="myapplication.audit">

              <priority value="DEBUG">priority>

              <appender-ref ref="FILE">appender-ref>

              <appender-ref ref="DB">appender-ref>

       category>

       <category  name="myapplication.test">

              <priority value="DEBUG">priority>

              <appender-ref ref="FILE">appender-ref>

       category>

      

       <root>

              <priority value="off">priority>

              <appender-ref ref="NULL">appender-ref>

       root>

      

log4j:configuration>

Please note we have defined separate category for audit “myapplication.audit” within log4j configuration. Further all the loggers have been created using “AuditLogger.class.getName()” e.g. Logger.getLogger(AuditLogger.class.getName()) where the value of AuditLogger.class.getName() is “myapplication.audit.AuditLogger”. Configuring a category with “myapplication.audit” would allow switching off audit logs if required.

Create a program to test auditing.

package myapplication.test;

import myapplication.audit.AuditLogger;

import org.apache.log4j.Logger;

public class TestAudit {

   public static void main (String args[]) {

         Logger.getLogger(TestAudit.class).debug("Before audit");

         AuditLogger.info("ashutosh","accesed", "User edit page");

         Logger.getLogger(TestAudit.class).debug("after audit");

   }

}

Compile it and execute it. Below is the output from mysql on querying audit table.

mysql> select * from audit;

Below are the logs shown from file after compiling and running the program.

2012-01-12 16:04:21,538 DEBUG [main] myapplication.test.TestAudit (TestAudit.java:10) - Before audit

2012-01-12 16:04:21,541 INFO  [main] myapplication.test.TestAudit (TestAudit.java:11) - User edit page

2012-01-12 16:04:21,767 DEBUG [main] myapplication.test.TestAudit (TestAudit.java:12) - after audit

Please note the output for both application log and audit has been redirected to file. This way you can easily track application logs and audit from same place.  We can also see the value of caller issuing the logging request is “myapplication.test.TestAudit” instead of “myapplication.audit.AuditLogger”; it has been achieved by using FQCN.

Logger.getLogger(AuditLogger.class.getName()).log(FQCN, Level.INFO,  activityDetail, null);

This method allows logging messages from a wrapper class.