ซึ่งสามารถหาดูตัวอย่างและdownload source code มาใช้งานได้ที่ http://poi.apache.org

โดยเราสามารถแบ่ง Component ใน POIได้เป็นส่วนๆดังนี้

• Excel
• Word
• PowerPoint
• OpenXML4J
• OLE2 FileSystem
• Outlook
• Visio
• Publisher

    โดยส่วนที่ผมต้องการจะกล่าวถึงคือส่วนของ Word(HWPF+XHWPF) โดยเนื้อหาที่ต้อง
การกล่าวถึงคือการใช้ POI ในการเขียน Word อย่างง่ายขึ้นมาเพื่อ ตอบสนองความต้องการในการเขียน
เอกสารอย่างง่ายด้วยภาษา JAVA
    ในที่นี้ผมจะเรียกComponent ในส่วนนี้ว่า HWPFโดยเรียกตามเอกสารของApache POI
HWPF มีความสามารถในการเขีบยน File เอกสารเพื่อให้ Microsoft Word 97-2007อ่านFileเอกสาร
และไม่รองรับการอ่านเอกสารแบบ.docx

ข้อดี

• สามารถเขียน File Word Document
• Open Source

ข้อเสีย

• มีปัญหาเรื่องภาษาไทย
• ไม่สามารถแทรกรุป หรือ ตารางได้
• HWPF ไม่มีการพัฒนาต่อในช่วงปี2009

ตัวอย่างcode การเขียน  worddocument โดยใช้poi

	import java.io.*;
	import org.apache.poi.hpsf.CustomProperties;
	import org.apache.poi.hpsf.DocumentSummaryInformation;
	import org.apache.poi.hwpf.HWPFDocument;
	import org.apache.poi.hwpf.usermodel.*;
	import org.apache.poi.poifs.filesystem.POIFSFileSystem;

	public class CreateWordDoc {
	    public static void main(String[] args) throws Exception {
	        // POI apparently can't create a document from scratch,
	        // so we need an existing empty dummy document
	        POIFSFileSystem fs = new POIFSFileSystem(new FileInputStream("c:\\data\\sample.dot"));
	        HWPFDocument doc = new HWPFDocument(fs);

	        // centered paragraph with large font size
	        Range range = doc.getRange();
	        Range r1 = doc.getRange();

	        for (int i = 0; i < r1.numSections(); ++i) {
	            Section s = r1.getSection(i);
	            for (int x = 0; x < s.numParagraphs(); x++) {
	                Paragraph p = s.getParagraph(x);
	                for (int z = 0; z < p.numCharacterRuns(); z++) {
	                    // character run
	                    CharacterRun run = p.getCharacterRun(z);
	                    // character run text
	                    String text = run.text();
	                    if (text.equalsIgnoreCase("CurrDate")) {
	                        String theDate = "28-05-2009";
	                        if (theDate != null) {
	                            run.replaceWith(theDate);
	                        }
	                    }
	                    if (text.equalsIgnoreCase("XYZ")) {
	                        String theapplicantName = "Mr.John";
	                        if (theapplicantName != null) {
	                            run.replaceWith(theapplicantName);
	                        }
	                    }
	                }
	            }
	        }

	        // add a custom document property (needs POI 3.5; POI 3.2 doesn't save
	        // custom properties)
	        DocumentSummaryInformation dsi = doc.getDocumentSummaryInformation();
	        CustomProperties cp = dsi.getCustomProperties();
	        if (cp == null)
	            cp = new CustomProperties();
	        cp.put("myProperty", "foo bar baz");
	        dsi.setCustomProperties(cp);
	        doc.write(new FileOutputStream("c:\\data\\new-hwpf-file.doc"));
	    }
	}

สรุป

First

I have to mention about setting multiple Java runtime options. We know each option is separate by space

example:

java -Xms128M -Xmx512M

The problem is having a space in JAVA_OPTS leading to having a space in execute command in the last part of core script.

If you use normal setting, Tomcat will execute by this line.

%_EXECJAVA% %JAVA_OPTS% %CATALINA_OPTS% %DEBUG_OPTS% -Djava.endorsed.dirs="%JAVA_ENDORSED_DIRS%" -classpath "%CLASSPATH%" -Dcatalina.base="%CATALINA_BASE%" -Dcatalina.home="%CATALINA_HOME%" -Djava.io.tmpdir="%CATALINA_TMPDIR%" %MAINCLASS% %CMD_LINE_ARGS% %ACTION%

If you trace back to find the real command of this line you will see that the %_EXECJAVA% is set by this statements

if not "%OS%" == "Windows_NT" goto noTitle
set _EXECJAVA=start "Tomcat" %_RUNJAVA%
goto gotTitle
:noTitle
set _EXECJAVA=start %_RUNJAVA%

Thats mean the real command that execute in execution line is start with a lot of arguments. So the %JAVA_OPTS% is only an argument of start command. This explained why setting value of multiple Java runtime options in %JAVA_OPTS% as normal multiple Java runtime options when you call java is not working here. Because a space in normal multiple Java runtime options will treat as argument separator of start command and your second Java runtime options will treat as an argument next to %JAVA_OPTS%. Now we know what is the problem and everyone know how to fix the problem ?Just add double quote around value of %JAVA_OPTS%? but is it enough?.

While our propose now is printing double quote around value of %JAVA_OPTS% in execution command but the double quote is a wrapper sign of batch script. So the line

set JAVA_OPTS="-Xms128M -Xmx512M"

will print

-Xms128M -Xmx512M

without double quote around it in the %JAVA_OPTS% part of start command. Yes, have or have not double quote around the value of set JAVA_OPTS= is the same.

You have two easy options to force printing double quote around value of %JAVA_OPTS% in execution command.

One is

add double quote around %JAVA_OPTS% in each execution line. The fixed version of the above execution line will look like this

%_EXECJAVA% "%JAVA_OPTS%" %CATALINA_OPTS% %DEBUG_OPTS% -Djava.endorsed.dirs="%JAVA_ENDORSED_DIRS%" -classpath "%CLASSPATH%" -Dcatalina.base="%CATALINA_BASE%" -Dcatalina.home="%CATALINA_HOME%" -Djava.io.tmpdir="%CATALINA_TMPDIR%" %MAINCLASS% %CMD_LINE_ARGS% %ACTION%

But don’t forget that it has 4 execution line in Tomcat’s core script. Luckily they are at the last part of the script.

The other way

is adding double quote around double quoted value of set JAVA_OPTS=. The fixed version of set JAVA_OPTS= line will look like this

set JAVA_OPTS=""-Xms128M -Xmx512M""

Yes, its look funny but its work because double quote mean using everything inside double quote as is. As a result, the value of %JAVA_OPTS% is “-Xms128M -Xmx512M” with double quote around it and it will print those double quote in to execution line.

I prefer to latter way because we do not edit any Tomcat’s core script. We only fix our added line

set JAVA_OPTS=""-Xms128M -Xmx512M""

in order to make our application usable.