iText7 Java 添加文本问题

Question

我正在使用 iText 7 复制 pdf 页面并对这些页面进行编号。所以我不需要手动给它们编号。但是生成的pdf文件中的数字有问题。这是它的样子：

而且我想了好几个小时，还是想不通。

我的代码：

import com.itextpdf.io.font.FontConstants;
import com.itextpdf.kernel.font.PdfFontFactory;
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfPage;
import com.itextpdf.kernel.pdf.PdfReader;
import com.itextpdf.kernel.pdf.PdfWriter;
import com.itextpdf.kernel.pdf.canvas.PdfCanvas;

import java.io.File;
import java.io.IOException;

public class NumberingInJava {

public static final String SRC = "D:/temp/num_src.pdf";
public static final String DEST = "D:/temp/edited_numbering.pdf";

public static final String[] NUM4SAMPLE = {"02A", "03A", "03B", "03C", "04A", "08A"};

public static final double XCOOR = 230;
public static final double YCOOR = 795;//755

public static void main(String[] args) throws IOException {
    File file = new File(DEST);
    file.getParentFile().mkdirs();
    new NumberingInJava().manipulatePdf(SRC, DEST, NUM4SAMPLE);
}

private void manipulatePdf(String src, String dest, String[] numbering4what) throws IOException {

    //Initialize PDF document
    PdfDocument pdfDocToRead = new PdfDocument(new PdfReader(src));
    PdfDocument pdfDocToWrite = new PdfDocument(new PdfWriter(dest));

    for(String s : numbering4what) {
        println(s);
    }

    String number = null;
    PdfPage tempPage = null;
    for (int i=0; i<numbering4what.length; i++) {
        pdfDocToRead.copyPagesTo(1, 2, pdfDocToWrite);
        number = numbering4what[i];
        println(number);
        tempPage = pdfDocToWrite.getPage(2*(i+1)-1);

        numberingPage(tempPage, number);

        println("pdfDocToWrite.numberOfPages : "+pdfDocToWrite.getNumberOfPages());
    }

    pdfDocToRead.close();
    pdfDocToWrite.close();

    println("\nNumber added!");
}

private void numberingPage(PdfPage pdfPage, String number) throws IOException {
    println(pdfPage);
    PdfCanvas canvas = new PdfCanvas(pdfPage);
    canvas.beginText().setFontAndSize(PdfFontFactory.createFont(FontConstants.HELVETICA), 22)
            .moveText(XCOOR, YCOOR)
            .showText(number)
            .endText();

    println("number: "+number);

}

private void println(Object obj) {
    System.out.println(obj);
}
}

控制台输出：

02A 03A 03B 03C 04A 08A 02A com.itextpdf.kernel.pdf.PdfPage@cf768c 17:58:07,457 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Could NOT find resource [logback.groovy] 17:58:07,458 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Could NOT find resource [logback-test.xml] 17:58:07,458 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Found resource [logback.xml] at [jar:file:/D:/Java_Packages/ext_lib/iText/itext7-7.0.1/itext7-itext-rups-7.0.1.jar!/logback.xml] 17:58:07,459 |-WARN in ch.qos.logback.classic.LoggerContext[default] - Resource [logback.xml] occurs multiple times on the classpath. 17:58:07,459 |-WARN in ch.qos.logback.classic.LoggerContext[default] - Resource [logback.xml] occurs at [jar:file:/D:/Java_Packages/ext_lib/iText/itext7-7.0.1/itext7-itext-rups-7.0.1-jar-with-dependencies.jar!/logback.xml] 17:58:07,459 |-WARN in ch.qos.logback.classic.LoggerContext[default] - Resource [logback.xml] occurs at [jar:file:/D:/Java_Packages/ext_lib/iText/itext7-7.0.1/itext7-itext-rups-7.0.1-sources.jar!/logback.xml] 17:58:07,459 |-WARN in ch.qos.logback.classic.LoggerContext[default] - Resource [logback.xml] occurs at [jar:file:/D:/Java_Packages/ext_lib/iText/itext7-7.0.1/itext7-itext-rups-7.0.1.jar!/logback.xml] 17:58:07,501 |-INFO in ch.qos.logback.core.joran.spi.ConfigurationWatchList@8080bb - URL [jar:file:/D:/Java_Packages/ext_lib/iText/itext7-7.0.1/itext7-itext-rups-7.0.1.jar!/logback.xml] is not of type file 17:58:07,662 |-INFO in ch.qos.logback.classic.joran.action.ConfigurationAction - debug attribute not set 17:58:07,829 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - About to instantiate appender of type [com.itextpdf.rups.view.DebugAppender] 17:58:07,851 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - Naming appender as [DEFAULT_APP] 17:58:07,940 |-INFO in ch.qos.logback.core.joran.action.NestedComplexPropertyIA - Assuming default type [ch.qos.logback.classic.encoder.PatternLayoutEncoder] for [encoder] property 17:58:08,045 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - About to instantiate appender of type [com.itextpdf.rups.view.StyleAppender] 17:58:08,046 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - Naming appender as [INFO_APP] 17:58:08,062 |-INFO in ch.qos.logback.core.joran.action.NestedComplexPropertyIA - Assuming default type [ch.qos.logback.classic.encoder.PatternLayoutEncoder] for [encoder] property 17:58:08,063 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - About to instantiate appender of type [com.itextpdf.rups.view.DebugAppender] 17:58:08,063 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - Naming appender as [DEBUG_APP] 17:58:08,065 |-INFO in ch.qos.logback.core.joran.action.NestedComplexPropertyIA - Assuming default type [ch.qos.logback.classic.encoder.PatternLayoutEncoder] for [encoder] property 17:58:08,066 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - About to instantiate appender of type [com.itextpdf.rups.view.DebugAppender] 17:58:08,066 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - Naming appender as [TRACE_APP] 17:58:08,067 |-INFO in ch.qos.logback.core.joran.action.NestedComplexPropertyIA - Assuming default type [ch.qos.logback.classic.encoder.PatternLayoutEncoder] for [encoder] property 17:58:08,069 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - About to instantiate appender of type [com.itextpdf.rups.view.StyleAppender] 17:58:08,069 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - Naming appender as [IMPORTANT_APP] 17:58:08,075 |-INFO in ch.qos.logback.core.joran.action.NestedComplexPropertyIA - Assuming default type [ch.qos.logback.classic.encoder.PatternLayoutEncoder] for [encoder] property 17:58:08,076 |-INFO in ch.qos.logback.classic.joran.action.LoggerAction - Setting additivity of logger [com.itextpdf] to false 17:58:08,077 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [IMPORTANT_APP] to Logger[com.itextpdf] 17:58:08,078 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [INFO_APP] to Logger[com.itextpdf] 17:58:08,078 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [DEBUG_APP] to Logger[com.itextpdf] 17:58:08,078 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [TRACE_APP] to Logger[com.itextpdf] 17:58:08,078 |-INFO in ch.qos.logback.classic.joran.action.RootLoggerAction - Setting level of ROOT logger to TRACE 17:58:08,078 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [DEFAULT_APP] to Logger[ROOT] 17:58:08,078 |-INFO in ch.qos.logback.classic.joran.action.ConfigurationAction - End of configuration. 17:58:08,082 |-INFO in ch.qos.logback.classic.joran.JoranConfigurator@1c24521 - Registering current configuration as safe fallback point

number: 02A pdfDocToWrite.numberOfPages : 2 03A com.itextpdf.kernel.pdf.PdfPage@11aa95a number: 03A pdfDocToWrite.numberOfPages : 4 03B com.itextpdf.kernel.pdf.PdfPage@bc05a6 number: 03B pdfDocToWrite.numberOfPages : 6 03C com.itextpdf.kernel.pdf.PdfPage@ef309d number: 03C pdfDocToWrite.numberOfPages : 8 04A com.itextpdf.kernel.pdf.PdfPage@1fc609f number: 04A pdfDocToWrite.numberOfPages : 10 08A com.itextpdf.kernel.pdf.PdfPage@173813a number: 08A pdfDocToWrite.numberOfPages : 12

Number added!

Process finished with exit code 0

编辑：我已经在 dropbox 上上传了一个模拟文档和一个编辑过的文档，这里是： Simulated doc

edited Simulated doc

Answer 1

原因

问题是由于 iText 试图使结果 PDF 变小造成的：

当你多次复制pdfDocToRead的页面到pdfDocToWrite时，实际的页面内容流、页面资源等只复制一次，只是生成一个引用这些数据的小对象每个副本和页面一次。

这个优化还不是问题，但进一步的微优化是，在

PdfCanvas canvas = new PdfCanvas(pdfPage);

此 PdfCanvas 辅助方法用于检索将向其添加内容的内容流：

private static PdfStream getPageStream(PdfPage page) {
    PdfStream stream = page.getContentStream(page.getContentStreamCount() - 1);
    return stream == null || stream.getOutputStream() == null || stream.containsKey(PdfName.Filter) ? page.newContentStreamAfter() : stream;
}

如您所见，通常会向页面添加新的内容流 (page.newContentStreamAfter())；仅当已经存在内容流且此流没有过滤器（例如用于压缩）时，此现有内容流才用于将数据附加到。

对于您的文档，为每个源页面复制的单个内容流未压缩。因此，这两项优化会导致所有 PdfCanvas canvas 实例附加到同一个内容流。

解决方法

明显的解决方法包括绕过后者优化：替换行

PdfCanvas canvas = new PdfCanvas(pdfPage);

来自

PdfCanvas canvas = new PdfCanvas(pdfPage.newContentStreamAfter(), pdfPage.getResources(), pdfPage.getDocument());

（在StampPageNumbers.java方法中numberingPage）

如果原始内容流被压缩，这本质上也会发生这种情况。

（一般来说，实际上可能必须在当前内容流之前使用保存图形状态指令添加新的内容流，并最初在当前内容流之后向新内容流添加恢复图形状态指令；以防万一但是，对于您的示例文档，这不是必需的，因为当前内容不会对图形状态产生不利影响。）

iText7 Java 添加文本问题

iText7 Java adding text issue

java

groovy

itext

itext7

原因

解决方法