# javax.xml.stream.util

***

**1. Creating an XMLStreamWriter that filters out certain elements**

```java
import javax.xml.stream.XMLStreamWriter;
import javax.xml.stream.util.XMLOutputFilter;

public class ElementFilter extends XMLOutputFilter {

    private final String[] excludedElements;

    public ElementFilter(XMLStreamWriter writer, String... excludedElements) {
        super(writer);
        this.excludedElements = excludedElements;
    }

    @Override
    public void writeStartElement(String localName) throws XMLStreamException {
        if (!isExcludedElement(localName)) {
            super.writeStartElement(localName);
        }
    }

    private boolean isExcludedElement(String localName) {
        for (String excludedElement : excludedElements) {
            if (excludedElement.equals(localName)) {
                return true;
            }
        }
        return false;
    }
}
```

**2. Creating an XMLStreamReader that merges multiple XML streams**

```java
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.util.StreamReaderDelegate;

public class StreamMerger extends StreamReaderDelegate {

    private final XMLStreamReader[] readers;
    private int currentReaderIndex = 0;

    public StreamMerger(XMLStreamReader... readers) {
        super(readers[0]);
        this.readers = readers;
    }

    @Override
    public int next() throws XMLStreamException {
        int eventType = super.next();
        if (eventType == XMLStreamConstants.END_DOCUMENT) {
            currentReaderIndex++;
            if (currentReaderIndex < readers.length) {
                setParent(readers[currentReaderIndex]);
                eventType = super.next();
            }
        }
        return eventType;
    }
}
```

**3. Creating an XMLStreamWriter that validates XML against a schema**

```java
import javax.xml.stream.XMLStreamWriter;
import javax.xml.stream.util.XMLOutputFactoryAccessor;
import javax.xml.transform.stream.StreamSource;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;

public class SchemaValidatingWriter extends XMLStreamWriter {

    private final XMLStreamWriter writer;
    private final Schema schema;

    public SchemaValidatingWriter(XMLStreamWriter writer, String schemaLocation) throws XMLStreamException {
        this.writer = writer;
        SchemaFactory schemaFactory = SchemaFactory.newInstance("http://www.w3.org/2001/XMLSchema");
        schema = schemaFactory.newSchema(new StreamSource(schemaLocation));
    }

    @Override
    public void writeStartDocument() throws XMLStreamException {
        schema.newValidator().validate(writer);
    }

    @Override
    public void writeEndDocument() throws XMLStreamException {
        writer.writeEndDocument();
    }

    // Implement other XMLStreamWriter methods...
}
```

**4. Creating an XMLStreamReader that transforms XML using XSLT**

```java
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.util.StreamReaderDelegate;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;

public class XSLTTransformingReader extends StreamReaderDelegate {

    private final Transformer transformer;
    private final XMLStreamReader transformedReader;

    public XSLTTransformingReader(XMLStreamReader reader, String xsltLocation) throws XMLStreamException {
        super(reader);
        TransformerFactory transformerFactory = TransformerFactory.newInstance();
        transformer = transformerFactory.newTransformer(new StreamSource(xsltLocation));
        Source source = new StreamSource(reader);
        Result result = new StreamResult();
        transformer.transform(source, result);
        transformedReader = result.newXMLStreamReader();
    }

    @Override
    public XMLStreamReader getParent() {
        return transformedReader.getParent();
    }

    // Implement other XMLStreamReader methods...
}
```

**5. Creating an XMLStreamWriter that encrypts XML**

```java
import javax.xml.stream.XMLStreamWriter;
import javax.xml.stream.util.XMLOutputFactoryAccessor;
import javax.xml.transform.stream.StreamSource;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.stream.StreamResult;

public class EncryptingWriter extends XMLStreamWriter {

    private final XMLStreamWriter writer;
    private final Transformer transformer;

    public EncryptingWriter(XMLStreamWriter writer, String key) throws XMLStreamException {
        this.writer = writer;
        TransformerFactory transformerFactory = TransformerFactory.newInstance();
        transformer = transformerFactory.newTransformer(new StreamSource(key));
    }

    @Override
    public void writeStartDocument() throws XMLStreamException {
        writer.writeStartDocument();
        transformer.transform(new StreamSource(writer), new StreamResult(writer));
    }

    @Override
    public void writeEndDocument() throws XMLStreamException {
        transformer.transform(new StreamSource(writer), new StreamResult(writer));
        writer.writeEndDocument();
    }

    // Implement other XMLStreamWriter methods...
}
```

**6. Creating an XMLStreamReader that decrypts XML**

```java
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.util.StreamReaderDelegate;
import javax.xml.transform.stream.StreamSource;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.stream.StreamResult;

public class DecryptingReader extends StreamReaderDelegate {

    private final XMLStreamReader reader;
    private final Transformer transformer;

    public DecryptingReader(XMLStreamReader reader, String key) throws XMLStreamException {
        super(reader);
        this.reader = reader;
        TransformerFactory transformerFactory = TransformerFactory.newInstance();
        transformer = transformerFactory.newTransformer(new StreamSource(key));
    }

    @Override
    public XMLStreamReader getParent() {
        return transformer.transform(new StreamSource(reader), new StreamResult()).newXMLStreamReader();
    }

    // Implement other XMLStreamReader methods...
}
```

**7. Creating an XMLStreamWriter that compresses XML**

```java
import javax.xml.stream.XMLStreamWriter;
import javax.xml.stream.util.XMLOutputFactoryAccessor;
import javax.xml.transform.stream.StreamSource;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.stream.StreamResult;

public class Compressing

```