juneau-core/juneau-marshall/src/main/java/org/apache/juneau/transforms/InputStreamSwap.java

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package org.apache.juneau.transforms;

import static org.apache.juneau.internal.StringUtils.*;

import java.io.*;

import org.apache.juneau.*;
import org.apache.juneau.internal.*;
import org.apache.juneau.transform.*;

/**
 * Transforms <code>InputStreams</code> to {@link String Strings}.
 */
public abstract class InputStreamSwap extends StringSwap<InputStream> {

	/**
	 * Converts {@link InputStream InputStreams} to BASE-64 encoding.
	 */
	public static class Base64 extends InputStreamSwap {
		/**
		 * Converts the specified {@link InputStream} to a {@link String}.
		 */
		@Override /* PojoSwap */
		public String swap(BeanSession session, InputStream is) throws Exception {
			return base64Encode(toBytes(is));
		}

		/**
		 * Converts the specified {@link String} to an {@link InputStream}.
		 */
		@Override /* PojoSwap */
		public InputStream unswap(BeanSession session, String s, ClassMeta<?> hint) throws Exception {
			return toStream(base64Decode(s), hint);
		}
	}

	/**
	 * Converts {@link InputStream InputStreams} to hex encoding.
	 */
	public static class Hex extends InputStreamSwap {
		/**
		 * Converts the specified {@link InputStream} to a {@link String}.
		 */
		@Override /* PojoSwap */
		public String swap(BeanSession session, InputStream is) throws Exception {
			return toHex(toBytes(is));
		}

		/**
		 * Converts the specified {@link String} to an {@link InputStream}.
		 */
		@Override /* PojoSwap */
		public InputStream unswap(BeanSession session, String s, ClassMeta<?> hint) throws Exception {
			return toStream(fromHex(s), hint);
		}
	}

	/**
	 * Converts {@link InputStream InputStreams} to spaced-hex encoding.
	 */
	public static class SpacedHex extends InputStreamSwap {
		/**
		 * Converts the specified {@link InputStream} to a {@link String}.
		 */
		@Override /* PojoSwap */
		public String swap(BeanSession session, InputStream is) throws Exception {
			return toSpacedHex(toBytes(is));
		}

		/**
		 * Converts the specified {@link String} to an {@link InputStream}.
		 */
		@Override /* PojoSwap */
		public InputStream unswap(BeanSession session, String s, ClassMeta<?> hint) throws Exception {
			return toStream(fromSpacedHex(s), hint);
		}
	}

	/**
	 * Convert the specified input stream to a byte array.
	 *
	 * @param is The input stream to convert to bytes.
	 * @return The byte array.
	 * @throws IOException Thrown by input stream.
	 */
	protected byte[] toBytes(InputStream is) throws IOException {
		return IOUtils.readBytes(is);
	}


	/**
	 * Convert the specified byte array into an input stream.
	 *
	 * @param b The byte array.
	 * @param hint Contains a hint about what subtype is being requested.
	 * @return The byte array.
	 */
	protected InputStream toStream(byte[] b, ClassMeta<?> hint) {
		Class<?> c = hint == null ? InputStream.class : hint.getInnerClass();
		if (c == InputStream.class || c == ByteArrayInputStream.class)
			return new ByteArrayInputStream(b);
		return null;
	}
}