下面是示例代码从iText的动作NUP样品中如下:document.close()需要很长的时间来写PDF数据到硬盘
import java.io.FileOutputStream;
import java.io.IOException;
import java.sql.SQLException;
import com.itextpdf.text.Document;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.Rectangle;
import com.itextpdf.text.pdf.PdfContentByte;
import com.itextpdf.text.pdf.PdfImportedPage;
import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.PdfWriter;
public class NUpTool {
/** Format of the resulting PDF files. */
public static final String RESULT = "results/part2/chapter06/result%dup.pdf";
/**
* Manipulates a PDF file src with the file dest as result
* @param src the original PDF
* @param dest the resulting PDF
* @param pow the PDF will be N-upped with N = Math.pow(2, pow);
* @throws IOException
* @throws DocumentException
* @throws SQLException
*/
public void manipulatePdf(String src, String dest, int pow)
throws IOException, DocumentException {
// reader for the src file
PdfReader reader = new PdfReader(src);
// initializations
Rectangle pageSize = reader.getPageSize(1);
Rectangle newSize = (pow % 2) == 0 ?
new Rectangle(pageSize.getWidth(), pageSize.getHeight()) :
new Rectangle(pageSize.getHeight(), pageSize.getWidth());
Rectangle unitSize = new Rectangle(pageSize.getWidth(), pageSize.getHeight());
for(int i = 0; i < pow; i++) {
unitSize = new Rectangle(unitSize.getHeight()/2, unitSize.getWidth());
}
int n = (int) Math.pow(2, pow);
int r = (int) Math.pow(2, pow/2);
int c = n/r;
// step 1
Document document = new Document(newSize, 0, 0, 0, 0);
// step 2
PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream(String.format(dest, n)));
// step 3
document.open();
// step 4
PdfContentByte cb = writer.getDirectContent();
PdfImportedPage page;
Rectangle currentSize;
float offsetX, offsetY, factor;
int total = reader.getNumberOfPages();
for(int i = 0; i < total;) {
if(i % n == 0) {
document.newPage();
}
currentSize = reader.getPageSize(++i);
factor = Math.min(
unitSize.getWidth()/currentSize.getWidth(),
unitSize.getHeight()/currentSize.getHeight());
offsetX = unitSize.getWidth() * ((i % n) % c) + (unitSize.getWidth() - (currentSize.getWidth() * factor))/2f;
offsetY = newSize.getHeight() - (unitSize.getHeight() * (((i % n)/c) + 1)) + (unitSize.getHeight() - (currentSize.getHeight() * factor))/2f;
page = writer.getImportedPage(reader, i);
cb.addTemplate(page, factor, 0, 0, factor, offsetX, offsetY);
}
// step 5
document.close();
reader.close();
}
/**
* Main method.
* @param args no arguments needed
* @throws DocumentException
* @throws IOException
* @throws SQLException
*/
public static void main(String[] args)
throws IOException, DocumentException, SQLException {
Stationery.main(args);
new NUpTool().manipulatePdf(Stationery.RESULT, RESULT, 1);
new NUpTool().manipulatePdf(Stationery.RESULT, RESULT, 2);
new NUpTool().manipulatePdf(Stationery.RESULT, RESULT, 3);
new NUpTool().manipulatePdf(Stationery.RESULT, RESULT, 4);
}
}
,我尝试处理约700MB一个pdf文件,并且它几乎需要半个小时才能将pdf数据写入硬盘(我认为是“document.close()”需要很长时间),而我的电脑杯 I5-2430 2.4G内存6GB,硬盘520G 7200 RPM不太不好,所以我想问的是有无论如何做一些优化,以加快itext写入速度。
非常感谢
埃里克
运行该程序时,您允许JVM使用多少内存?考虑允许更多。 – mkl