问题

我正在使用pdfbox库的2.0版本。我必须从页面中删除所选图像并添加另一个图像。它可以正常运行。但是当我打开该文件时，会显示一个警告消息：***此页面存在错误。Acrobat可能无法正确显示页面***。如下是屏幕截图：

![错误图片][1]

下面是删除图像并添加其他图像的代码示例：（已编辑并修复）

```java
public static void removeImages(String pdfFile) throws Exception {
    PDDocument document = PDDocument.load(new File(pdfFile));

    for (PDPage page : document.getPages()) {
        PDResources pdResources = page.getResources();
        String[] qrCodeCosName = new String[1];

        pdResources.getXObjectNames().forEach(propertyName -> {
            if (!pdResources.isImageXObject(propertyName)) {
                return;
            }
            PDXObject o;
            try {
                o = pdResources.getXObject(propertyName);
                if (o instanceof PDImageXObject) {
                    PDImageXObject pdImageXObject = (PDImageXObject) o;
                    if (pdImageXObject.getMetadata() != null) {
                        // 从资源中移除
                        ((COSDictionary) pdResources.getCOSObject().getDictionaryObject(COSName.XOBJECT))
                                .removeItem(propertyName);
                        qrCodeCosName[0] = propertyName.getName();
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        });

        PDFStreamParser parser = new PDFStreamParser(page);
        parser.parse();
        List<Object> tokens = parser.getTokens();
        System.out.println("原始 tokens 大小：" + tokens.size());
        List<Object> newTokens = new ArrayList<Object>();

        for (int j = 0; j < tokens.size(); j++) {
            Object token = tokens.get(j);

            if (token instanceof Operator) {
                Operator op = (Operator) token;

                // 找到图像 - 删除它
                if (op.getName().equals("Do")) {
                    COSName cosName = (COSName) tokens.get(j - 1);
                    if (cosName.getName().equals(qrCodeCosName[0])) {
                        newTokens.remove(newTokens.size() - 1);
                        continue;
                    }
                }
                newTokens.add(token);
            }

            System.out.println("tokens 大小：" + newTokens.size());
            PDStream newContents = new PDStream(document);
            OutputStream out = newContents.createOutputStream();
            ContentStreamWriter writer = new ContentStreamWriter(out);
            writer.writeTokens(newTokens);
            out.close();
            page.setContents(newContents);

            // 添加其他图像
            PDImageXObject pdImage = PDImageXObject.createFromFile("D:\\copy\\ind.png", document);

            PDPageContentStream contents = new PDPageContentStream(document, page,
                    PDPageContentStream.AppendMode.PREPEND, true, true);

            contents.saveGraphicsState();
            // 在PDF文档中绘制图像
            contents.drawImage(pdImage, 0, 0, 50, 30);
            contents.restoreGraphicsState();

            System.out.println("成功插入图像。");

            // 关闭 PDPageContentStream 对象
            contents.close();

        }

        document.save("RemoveImage.pdf");
        document.close();
    }
}

请帮忙解决这个问题。
同时，期待关于其他代码审查意见，以使此操作正常运行。

[1]: https://i.stack.imgur.com/VJaec.png
<details>
<summary>英文:</summary>
I am using the pdfbox library 2.0 version. I have to remove the selected image from the page and add another image. It works properly. But when I open that file it shows a warning message: ***An error exists on this page. Acrobat may not display the page correctly***. and the screenshot is as below: 
![Error Image][1]
Herewith sharing the code to delete an image and add other image:**(EDITTED with Fix)**
public static void removeImages(String pdfFile) throws Exception {
PDDocument document = PDDocument.load(new File(pdfFile));
for (PDPage page : document.getPages()) {
PDResources pdResources = page.getResources();
String[] qrCodeCosName = new String[1];
pdResources.getXObjectNames().forEach(propertyName -&gt; {
if (!pdResources.isImageXObject(propertyName)) {
return;
}
PDXObject o;
try {
o = pdResources.getXObject(propertyName);
if (o instanceof PDImageXObject) {
PDImageXObject pdImageXObject = (PDImageXObject) o;
if (pdImageXObject.getMetadata() != null) {
// TO REMOVE FROM RESOURCE
((COSDictionary) pdResources.getCOSObject().getDictionaryObject(COSName.XOBJECT))
.removeItem(propertyName);
qrCodeCosName[0] = propertyName.getName();
}
}
} catch (IOException e) {
e.printStackTrace();
}
});
PDFStreamParser parser = new PDFStreamParser(page);
parser.parse();
List&lt;Object&gt; tokens = parser.getTokens();
System.out.println(&quot;Original tokens size&quot; + tokens.size());
List&lt;Object&gt; newTokens = new ArrayList&lt;Object&gt;();
for (int j = 0; j &lt; tokens.size(); j++) {
Object token = tokens.get(j);
if (token instanceof Operator) {
Operator op = (Operator) token;
// find image - remove it
if (op.getName().equals(&quot;Do&quot;)) {
COSName cosName = (COSName) tokens.get(j - 1);
if (cosName.getName().equals(qrCodeCosName[0])) {
newTokens.remove(newTokens.size() - 1);
continue;
}
}
newTokens.add(token);
}
System.out.println(&quot;tokens size&quot; + newTokens.size());
PDStream newContents = new PDStream(document);
OutputStream out = newContents.createOutputStream();
ContentStreamWriter writer = new ContentStreamWriter(out);
writer.writeTokens(newTokens);
out.close();
page.setContents(newContents);
// ADD OTHER IMAGE
PDImageXObject pdImage = PDImageXObject.createFromFile(&quot;D:\\copy\\ind.png&quot;, document);
PDPageContentStream contents = new PDPageContentStream(document, page,
PDPageContentStream.AppendMode.PREPEND, true, true);
contents.saveGraphicsState();
// Drawing the image in the PDF document
contents.drawImage(pdImage, 0, 0, 50, 30);
contents.restoreGraphicsState();
System.out.println(&quot;Image inserted Successfully.&quot;);
// Closing the PDPageContentStream object
contents.close();
}
document.save(&quot;RemoveImage.pdf&quot;);
document.close();
}
}
Kindly help me with this.
**Also, looking forward for other code review comments about required changes to make this operation properly.** :)
[1]: https://i.stack.imgur.com/VJaec.png
</details>
# 答案1
**得分**: 1
根据@Tilman Hausherr的建议，以下代码适用于我：
```java
public static void removeImages(String pdfFile) throws Exception {
PDDocument document = PDDocument.load(new File(pdfFile));
for (PDPage page : document.getPages()) {
PDResources pdResources = page.getResources();
String[] qrCodeCosName = new String[1];
pdResources.getXObjectNames().forEach(propertyName -> {
if (!pdResources.isImageXObject(propertyName)) {
return;
}
PDXObject o;
try {
o = pdResources.getXObject(propertyName);
if (o instanceof PDImageXObject) {
PDImageXObject pdImageXObject = (PDImageXObject) o;
if (pdImageXObject.getMetadata() != null) {
// TO REMOVE FROM RESOURCE
((COSDictionary) pdResources.getCOSObject().getDictionaryObject(COSName.XOBJECT))
.removeItem(propertyName);
qrCodeCosName[0] = propertyName.getName();
}
}
} catch (IOException e) {
e.printStackTrace();
}
});
PDFStreamParser parser = new PDFStreamParser(page);
parser.parse();
List<Object> tokens = parser.getTokens();
System.out.println("Original tokens size" + tokens.size());
List<Object> newTokens = new ArrayList<Object>();
for (int j = 0; j < tokens.size(); j++) {
Object token = tokens.get(j);
if (token instanceof Operator) {
Operator op = (Operator) token;
// find image - remove it
if (op.getName().equals("Do")) {
COSName cosName = (COSName) tokens.get(j - 1);
if (cosName.getName().equals(qrCodeCosName[0])) {
newTokens.remove(newTokens.size() - 1);
continue;
}
}
newTokens.add(token);
}
System.out.println("tokens size" + newTokens.size());
PDStream newContents = new PDStream(document);
OutputStream out = newContents.createOutputStream();
ContentStreamWriter writer = new ContentStreamWriter(out);
writer.writeTokens(newTokens);
out.close();
page.setContents(newContents);
// ADD OTHER IMAGE
PDImageXObject pdImage = PDImageXObject.createFromFile("D:\\copy\\ind.png", document);
PDPageContentStream contents = new PDPageContentStream(document, page,
PDPageContentStream.AppendMode.PREPEND, true, true);
contents.saveGraphicsState();
// Drawing the image in the PDF document
contents.drawImage(pdImage, 0, 0, 50, 30);
contents.restoreGraphicsState();
System.out.println("Image inserted Successfully.");
// Closing the PDPageContentStream object
contents.close();
}
document.save("RemoveImage.pdf");
document.close();
}
}

public static void removeImages(String pdfFile) throws Exception {
PDDocument document = PDDocument.load(new File(pdfFile));
for (PDPage page : document.getPages()) {
PDResources pdResources = page.getResources();
String[] qrCodeCosName = new String[1];
pdResources.getXObjectNames().forEach(propertyName -> {
if (!pdResources.isImageXObject(propertyName)) {
return;
}
PDXObject o;
try {
o = pdResources.getXObject(propertyName);
if (o instanceof PDImageXObject) {
PDImageXObject pdImageXObject = (PDImageXObject) o;
if (pdImageXObject.getMetadata() != null) {
// TO REMOVE FROM RESOURCE
((COSDictionary) pdResources.getCOSObject().getDictionaryObject(COSName.XOBJECT))
.removeItem(propertyName);
qrCodeCosName[0] = propertyName.getName();
}
}
} catch (IOException e) {
e.printStackTrace();
}
});
PDFStreamParser parser = new PDFStreamParser(page);
parser.parse();
List<Object> tokens = parser.getTokens();
System.out.println("Original tokens size" + tokens.size());
List<Object> newTokens = new ArrayList<Object>();
for (int j = 0; j < tokens.size(); j++) {
Object token = tokens.get(j);
if (token instanceof Operator) {
Operator op = (Operator) token;
// find image - remove it
if (op.getName().equals("Do")) {
COSName cosName = (COSName) tokens.get(j - 1);
if (cosName.getName().equals(qrCodeCosName[0])) {
newTokens.remove(newTokens.size() - 1);
continue;
}
}
newTokens.add(token);
}
System.out.println("tokens size" + newTokens.size());
PDStream newContents = new PDStream(document);
OutputStream out = newContents.createOutputStream();
ContentStreamWriter writer = new ContentStreamWriter(out);
writer.writeTokens(newTokens);
out.close();
page.setContents(newContents);
// ADD OTHER IMAGE
PDImageXObject pdImage = PDImageXObject.createFromFile("D:\\copy\\ind.png", document);
PDPageContentStream contents = new PDPageContentStream(document, page,
PDPageContentStream.AppendMode.PREPEND, true, true);
contents.saveGraphicsState();
// Drawing the image in the PDF document
contents.drawImage(pdImage, 0, 0, 50, 30);
contents.restoreGraphicsState();
System.out.println("Image inserted Successfully.");
// Closing the PDPageContentStream object
contents.close();
}
document.save("RemoveImage.pdf");
document.close();
}
}