Some elements have been added to the xml file through the add method. But why does the xml file leave a blank line after deleting an element, and how to get rid of it? The main function is:
@Test
public void test() {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
OperateXml operateXml = new OperateXml();
try {
DocumentBuilder builder = factory.newDocumentBuilder();
Document document = builder.parse(new ClassPathResource("chunkInfo/chunk.xml").getFile());
// operateXml.add(document);
operateXml.deleteNodeById(document,"id_5");
operateXml.saveDocument(document, new ClassPathResource("chunkInfo/chunk.xml").getFile());
} catch (Exception e) {
System.out.println(e);
}
}
The save function is:
public static void saveDocument(Document document, File xmlFile) {
TransformerFactory tff = TransformerFactory.newInstance();
try {
Transformer tf = tff.newTransformer();
tf.setOutputProperty(OutputKeys.DOCTYPE_SYSTEM, "chunk.dtd");
tf.setOutputProperty(OutputKeys.INDENT, "yes");
tf.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
tf.transform(new DOMSource(document), new StreamResult(xmlFile));
} catch (TransformerException e) {
e.printStackTrace();
}
}
Before deleting the element, the xml file is：
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE save SYSTEM "chunk.dtd">
<save>
<chunk id="id_1">
<name>test_6</name>
<type>log</type>
<item>2,3,4,5</item>
</chunk>
<chunk id="id_3">
<name>test_6</name>
<type>log</type>
<item>2,3,4,5</item>
</chunk>
<chunk id="id_4">
<name>test_6</name>
<type>log</type>
<item>2,3,4,5</item>
</chunk>
<chunk id="id_5">
<name>test_7</name>
<type>log</type>
<item>2,3,4,5</item>
</chunk>
</save>
After deleting the element (id="id_5"), the xml file is：
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE save SYSTEM "chunk.dtd">
<save>
<chunk id="id_1">
<name>test_6</name>
<type>log</type>
<item>2,3,4,5</item>
</chunk>
<chunk id="id_3">
<name>test_6</name>
<type>log</type>
<item>2,3,4,5</item>
</chunk>
<chunk id="id_4">
<name>test_6</name>
<type>log</type>
<item>2,3,4,5</item>
</chunk>
</save>
The reason is likely because there are invisible [text] nodes between your elements (in the example below '\n' is a newline and '\t' is a tab indent):
<save>[text '\n
\t']<chunk id="id_1">[text '\n
\t\t']<name>test_6</name>[text '\n
\t\t']<type>log</type>[text '\n
\t\t']<item>2,3,4,5</item>[text '\n
\t\t']</chunk>[text \n
\t']<chunk id="id_3">[text '\n
\t\t']<name>test_6</name>[text '\n
\t\t']<type>log</type>[text '\n
\t\t']<item>2,3,4,5</item>[text '\n
\t']</chunk>[text '\n
\t']<chunk id="id_4">[text '\n
\t\t']<name>test_6</name>[text '\n
\t\t']<type>log</type>[text '\n
\t\t']<item>2,3,4,5</item>[text '\n
\t']</chunk>[text '\n
\t']<chunk id="id_5">[text '\n
\t\t']<name>test_7</name>[text '\n
\t\t']<type>log</type>[text '\n
\t\t']<item>2,3,4,5</item>[text '\n
\t']</chunk>[text '\n']
</save>
When you remove everything under <chunk id="id_5"> it leaves the [text] nodes around it.
<save>[text '\n
\t']<chunk id="id_1">[text '\n
\t\t']<name>test_6</name>[text '\n
\t\t']<type>log</type>[text '\n
\t\t']<item>2,3,4,5</item>[text '\n
\t\t']</chunk>[text \n
\t']<chunk id="id_3">[text '\n
\t\t']<name>test_6</name>[text '\n
\t\t']<type>log</type>[text '\n
\t\t']<item>2,3,4,5</item>[text '\n
\t']</chunk>[text '\n
\t']<chunk id="id_4">[text '\n
\t\t']<name>test_6</name>[text '\n
\t\t']<type>log</type>[text '\n
\t\t']<item>2,3,4,5</item>[text '\n
\t']</chunk>[text '\n
\t'][..where chunk used to be..][text '\n']
</save>
One option to resolve this would be to re-format the document.
Another is to get the reference to the element you want to delete, check its preceding sibling node, and if it's a blank text node then remove it as well.
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