COSStream 已经关闭，无法读取。也许它的封闭 PDDocument 已经关闭？

Question

基本上，我试图在 Java 中创建一个小工具，我从某种用户输入中获取文本，想像一个普通的文本框，并用它创建一个 PDF 文件。

到目前为止，我利用我对 PDFBox 的准系统知识非常快速地抓取了一些东西。

在我的应用程序中，我在另一个具有 GUI 元素的应用程序中实例化这个 class（如下所示），如果我输入文本，假设是一个文本框，运行这个PDFLetter 脚本一次 - 它工作得很好但是运行第二次，它崩溃并给我这个烦人的错误：

COSStream has been closed and cannot be read. Perhaps it's enclosing PDDocument has been closed?

我真的看不出有什么方法可以在我的代码中触发这个错误。我认为这与我的基本 'jump to next page' 解决方案有关，但它在当前状态下有效，所以我不知道该相信什么了。

我实例化 class 的方式是这样的：

PDFLetter.PDFLetterGenerate(textInput.getValue().toString());

此外，我认为一定是垃圾回收的某种问题触发了这个问题，但我不再认为是这种情况。

public class PDFLetter {
    private static final int PAGE_MARGIN = 80;

    static float TABLE_HEIGHT;  

    static Boolean newPage = false;

public static String text = // null;
        "Ding Dong ding dong Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et "
        + "Imperdiet dui accumsan sit amet. Risus in hendrerit gravida rutrum quisque non tellus orci ac.";

static List<String> textList = new ArrayList<String>();

PDDocument document = new PDDocument();
static PDPage main_page = new PDPage();
static PDPage new_page = new PDPage(); 

static File file = new File("C:/PDFTests/temp.pdf"); 

public void PDFLetterGenerate (String args) throws Exception {
    text = args;
    text = text.replace("\n", "").replace("\r", "");

    if(file.exists()) file.delete();
    file.createNewFile();
    //Creating PDF document object 
    PDDocument document = new PDDocument();       
    document.addPage(main_page);  
    mainBody(document, main_page);      
    document.addPage(new_page);                          
    if(!newPage) document.removePage(new_page);

    document.save(file);
    document.close(); 
}

public static void mainBody(PDDocument doc, PDPage page) throws Exception { 
        final float width = page.getMediaBox().getWidth()-(2*PAGE_MARGIN);
        int fontSize = 11;
        float leading = 1.5f * fontSize;
        final float max = 256;
        PDFont pdfFont = PDType1Font.HELVETICA;

        @SuppressWarnings("deprecation")
        PDPageContentStream contentStream = new PDPageContentStream(doc, page, true, true);

        int lastSpace = -1;
        while (text.length() > 0){
            int spaceIndex = text.indexOf(' ', lastSpace + 1);
            if (spaceIndex < 0) spaceIndex = text.length();
            String subString = text.substring(0, spaceIndex);
            float size = fontSize * pdfFont.getStringWidth(subString) / 1000;

            if (size > width){
                if (lastSpace < 0) lastSpace = spaceIndex;
                subString = text.substring(0, lastSpace);
                textList.add(subString);
                text = text.substring(lastSpace).trim();
                lastSpace = -1;
            }

            else if (spaceIndex == text.length()){
                textList.add(text);
                text = "";
            }

            else{
                lastSpace = spaceIndex;
            }
        }

        contentStream.beginText();
        contentStream.setFont(pdfFont, fontSize);
        contentStream.newLineAtOffset(PAGE_MARGIN, TABLE_HEIGHT);


        @SuppressWarnings("deprecation")
        PDPageContentStream newStream = new PDPageContentStream(doc, new_page, true, true);

        int nextPage_i = 0;

        for (int i=0; i<textList.size(); i++)//String line: textList){
            System.out.println("HEIGHT: "+ TABLE_HEIGHT);
            nextPage_i = i;
            String line = textList.get(i);
            float charSpacing = 0;

            if (line.length() > 1){         
                float size = fontSize * pdfFont.getStringWidth(line) / 1000;
                float free = width - size;
                if (free > 0){
                    charSpacing = free / (line.length() - 1);
                }
                TABLE_HEIGHT = TABLE_HEIGHT - 10;
            }

            contentStream.setCharacterSpacing(charSpacing); 
            contentStream.showText(line);
            contentStream.newLineAtOffset(0, -leading);

            if(TABLE_HEIGHT <= 280){  
                contentStream.endText();  
                contentStream.close(); 
                newPage = true;
                break; 
            } 
        } 

        if(!newPage){
            contentStream.endText();  
            contentStream.close(); 
        }

        else if (newPage){          
            float NEW_HEIGHT = 600;             
            newStream.beginText();
            newStream.setFont(pdfFont, fontSize);
            newStream.newLineAtOffset(PAGE_MARGIN, NEW_HEIGHT);

            for (int j=nextPage_i; j<textList.size(); j++)//String line: textList){
                System.out.println("HEIGHT: "+ NEW_HEIGHT);
                nextPage_i = j;
                String line = textList.get(j);
                float charSpacing = 0;

                if (line.length() > 1){         
                    float size = fontSize * pdfFont.getStringWidth(line) / 1000;
                    float free = width - size;
                    if (free > 0)
                    {
                        charSpacing = free / (line.length() - 1);
                    }
                    NEW_HEIGHT = NEW_HEIGHT - 10; 
                }
                newStream.setCharacterSpacing(charSpacing); 
                newStream.showText(line);
                newStream.newLineAtOffset(0, -leading);
            }
            newStream.endText();  
            newStream.close();
        }
        lastSpace = -1;
    }

Answer 1

将 PDPage 个实例拉入 PDFLetterGenerate:

public void PDFLetterGenerate (String args) throws Exception {
    PDPage main_page = new PDPage();
    PDPage new_page = new PDPage(); 

    text = args;
    text = text.replace("\n", "").replace("\r", "");

    if(file.exists()) file.delete();
    file.createNewFile();
    //Creating PDF document object 
    PDDocument document = new PDDocument();       
    document.addPage(main_page);  
    mainBody(document, main_page);      
    document.addPage(new_page);                          
    if(!newPage) document.removePage(new_page);

    document.save(file);
    document.close(); 
}

在您的代码中，页面被实例化一次，基础流在 PDFLetterGenerate 的第一个运行之后关闭，而本地 PDDocument document 在添加页面后关闭.

此外，还使 new_page 成为 mainBody 的参数，而不是指望静态变量来保存它。

您的代码中还有许多其他问题，但上述更改应该可以帮助您入门。

COSStream 已经关闭，无法读取。也许它的封闭 PDDocument 已经关闭？

COSStream has been closed and cannot be read. Perhaps its enclosing PDDocument has been closed?

java

pdf-generation

pdfbox