Java Wrapping an InputStream

I need to repeatedly read from an InputStream. The stream is from reading some XML from a web service request. I'd like to keep the XML in memory so I may parse the stream multiple times, and ultimately trash the XML at some later time. What 开发者_如何学Ccan I wrap the InputStream in so I may access it multiple times?

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Assuming you're reading in a well-structured XML document, why not parse the document a single time using a DOM parser (for example, javax.xml.parsers.DocumentBuilder)?

This will provide you with an in-memory representation of the XML document in a structured format. If you use a parser like DocumentBuilder, you can subsequently fetch various parts of the structured data using the methods Node like getElementsByTagName, etc.

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You can try

byte[] bytes = IOUtils.toByteArray(inputStream);

// as often as desired.
ByteArrayInputStream bais = new ByteArrayInputStream(bytes);

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Apache Commons IO has a utility method that will read an input stream into a byte array (if you didn't want to write the function yourself) you could then wrap that in a ByteArrayInputStream i.e.

InputStream xmlInput = ...;
InputStream rereadableStream = 
    new ByteArrayInputStream(IOUtils.toByteArray(xmlInput));

and then use mark() / reset() or simply save the byte array and construct a new ByteArrayInputStream when needed.