Introduce HttpHeaders get/setContentDisposition()

This commit introduces a new ContentDisposition class designed
to parse and generate Content-Disposition header value as defined
in RFC 2183. It supports the disposition type and the name,
filename (or filename* when encoded according to RFC 5987) and
size parameters.

This new class is usually used thanks to
HttpHeaders#getContentDisposition() and
HttpHeaders#setContentDisposition(ContentDisposition).

Issue: SPR-14408

spring-web/src/main/java/org/springframework/http/ContentDisposition.java

@@ -0,0 +1,383 @@
+/*
+ * Copyright 2002-2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.http;
+
+import java.io.ByteArrayOutputStream;
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
+
+import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
+
+/**
+ * Represent the content disposition type and parameters as defined in RFC 2183.
+ *
+ * @author Sebastien Deleuze
+ * @since 5.0
+ * @see <a href="https://tools.ietf.org/html/rfc2183">RFC 2183</a>
+ */
+public class ContentDisposition {
+
+	private final String type;
+
+	private final String name;
+
+	private final String filename;
+
+	private final Charset charset;
+
+	private final Long size;
+
+	/**
+	 * Create a {@code ContentDisposition} instance with the specified disposition type
+	 * and {@litteral name}, {@litteral filename} (encoded with the specified {@link Charset}
+	 * if any) and {@litteral size} parameter values.
+	 */
+	private ContentDisposition(String type, String name, String filename, Charset charset, Long size) {
+		this.type = type;
+		this.name = name;
+		this.filename = filename;
+		this.charset = charset;
+		this.size = size;
+	}
+
+	/**
+	 * Return a builder for a {@code ContentDisposition}.
+	 * @param type the disposition type like for example {@literal inline}, {@literal attachment},
+	 * or {@literal form-data}
+	 * @return a content disposition builder
+	 */
+	public static Builder builder(String type) {
+		return new BuilderImpl(type);
+	}
+
+	/**
+	 * @return an empty content disposition
+	 */
+	public static ContentDisposition empty() {
+		return new ContentDisposition(null, null, null, null, null);
+	}
+
+	/**
+	 * Return the disposition type, like for example {@literal inline}, {@literal attachment},
+	 * {@literal form-data}, or {@code null} if not defined.
+	 */
+	public String getType() {
+		return this.type;
+	}
+
+	/**
+	 * Return the value of the {@literal name} parameter, or {@code null} if not defined.
+	 */
+	public String getName() {
+		return this.name;
+	}
+
+	/**
+	 * Return the value of the {@literal filename} parameter (or the value of the
+	 * {@literal filename*} one decoded as defined in the RFC 5987), or {@code null} if not defined.
+	 */
+	public String getFilename() {
+		return this.filename;
+	}
+
+	/**
+	 * Return the charset defined in {@literal filename*} parameter, or {@code null} if not defined.
+	 */
+	public Charset getCharset() {
+		return this.charset;
+	}
+
+	/**
+	 * Return the value of the {@literal size} parameter, or {@code null} if not defined.
+	 */
+	public Long getSize() {
+		return this.size;
+	}
+
+	/**
+	 * Parse a {@literal Content-Disposition} header value as defined in RFC 2183.
+	 * @param contentDisposition the {@literal Content-Disposition} header value
+	 * @return the parsed content disposition
+	 * @see #toString()
+	 */
+	public static ContentDisposition parse(String contentDisposition) {
+		String[] parts = StringUtils.tokenizeToStringArray(contentDisposition, ";");
+		Assert.isTrue(parts.length >= 1);
+		String type = parts[0];
+		String name = null;
+		String filename = null;
+		Charset charset = null;
+		Long size = null;
+		for (int i = 1; i < parts.length; i++) {
+			String parameter = parts[i];
+			int eqIndex = parameter.indexOf('=');
+			if (eqIndex != -1) {
+				String attribute = parameter.substring(0, eqIndex);
+				String value = (parameter.startsWith("\"", eqIndex + 1) && parameter.endsWith("\"") ?
+						parameter.substring(eqIndex + 2, parameter.length() - 1) :
+						parameter.substring(eqIndex + 1, parameter.length()));
+				if (attribute.equals("name") ) {
+					name = value;
+				}
+				else if (attribute.equals("filename*") ) {
+					filename = decodeHeaderFieldParam(value);
+					charset = Charset.forName(value.substring(0, value.indexOf("'")));
+					Assert.isTrue(StandardCharsets.UTF_8.equals(charset) || StandardCharsets.ISO_8859_1.equals(charset),
+							"Charset should be UTF-8 or ISO-8859-1");
+				}
+				else if (attribute.equals("filename") && (filename == null)) {
+					filename = value;
+				}
+				else if (attribute.equals("size") ) {
+					size = Long.parseLong(value);
+				}
+			}
+			else {
+				throw new IllegalArgumentException("Invalid content disposition format");
+			}
+		}
+		return new ContentDisposition(type, name, filename, charset, size);
+	}
+
+	/**
+	 * Encode the given header field param as describe in RFC 5987.
+	 * @param input the header field param
+	 * @param charset the charset of the header field param string,
+	 * only the US-ASCII, UTF-8 and ISO-8859-1 charsets are supported
+	 * @return the encoded header field param
+	 * @see <a href="https://tools.ietf.org/html/rfc5987">RFC 5987</a>
+	 */
+	private static String encodeHeaderFieldParam(String input, Charset charset) {
+		Assert.notNull(input, "Input String should not be null");
+		Assert.notNull(charset, "Charset should not be null");
+		if (StandardCharsets.US_ASCII.equals(charset)) {
+			return input;
+		}
+		Assert.isTrue(StandardCharsets.UTF_8.equals(charset) || StandardCharsets.ISO_8859_1.equals(charset),
+				"Charset should be UTF-8 or ISO-8859-1");
+		byte[] source = input.getBytes(charset);
+		int len = source.length;
+		StringBuilder sb = new StringBuilder(len << 1);
+		sb.append(charset.name());
+		sb.append("''");
+		for (byte b : source) {
+			if (isRFC5987AttrChar(b)) {
+				sb.append((char) b);
+			}
+			else {
+				sb.append('%');
+				char hex1 = Character.toUpperCase(Character.forDigit((b >> 4) & 0xF, 16));
+				char hex2 = Character.toUpperCase(Character.forDigit(b & 0xF, 16));
+				sb.append(hex1);
+				sb.append(hex2);
+			}
+		}
+		return sb.toString();
+	}
+
+	/**
+	 * Decode the given header field param as describe in RFC 5987.
+	 * <p>Only the US-ASCII, UTF-8 and ISO-8859-1 charsets are supported.
+	 * @param input the header field param
+	 * @return the encoded header field param
+	 * @see <a href="https://tools.ietf.org/html/rfc5987">RFC 5987</a>
+	 */
+	private static String decodeHeaderFieldParam(String input) {
+		Assert.notNull(input, "Input String should not be null");
+		int firstQuoteIndex = input.indexOf("'");
+		int secondQuoteIndex = input.indexOf("'", firstQuoteIndex + 1);
+		// US_ASCII
+		if (firstQuoteIndex == -1 || secondQuoteIndex == -1) {
+			return input;
+		}
+		Charset charset = Charset.forName(input.substring(0, firstQuoteIndex));
+		Assert.isTrue(StandardCharsets.UTF_8.equals(charset) || StandardCharsets.ISO_8859_1.equals(charset),
+				"Charset should be UTF-8 or ISO-8859-1");
+		byte[] value = input.substring(secondQuoteIndex + 1, input.length()).getBytes(charset);
+		ByteArrayOutputStream bos = new ByteArrayOutputStream();
+		int index = 0;
+		while (index < value.length) {
+			byte b = value[index];
+			if (isRFC5987AttrChar(b)) {
+				bos.write((char) b);
+				index++;
+			}
+			else if (b == '%') {
+				char[] array = { (char)value[index + 1], (char)value[index + 2]};
+				bos.write(Integer.parseInt(String.valueOf(array), 16));
+				index+=3;
+			}
+			else {
+				throw new IllegalArgumentException("Invalid header field parameter format (as defined in RFC 5987)");
+			}
+		}
+		return new String(bos.toByteArray(), charset);
+	}
+
+	private static boolean isRFC5987AttrChar(byte c) {
+		return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
+				c == '!' || c == '#' || c == '$' || c == '&' || c == '+' || c == '-' ||
+				c == '.' || c == '^' || c == '_' || c == '`' || c == '|' || c == '~';
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (this == o) {
+			return true;
+		}
+		if (o == null || getClass() != o.getClass()) {
+			return false;
+		}
+		ContentDisposition that = (ContentDisposition) o;
+		if (type != null ? !type.equals(that.type) : that.type != null) {
+			return false;
+		}
+		if (name != null ? !name.equals(that.name) : that.name != null) {
+			return false;
+		}
+		if (filename != null ? !filename.equals(that.filename) : that.filename != null) {
+			return false;
+		}
+		if (charset != null ? !charset.equals(that.charset) : that.charset != null) {
+			return false;
+		}
+		return size != null ? size.equals(that.size) : that.size == null;
+	}
+
+	@Override
+	public int hashCode() {
+		int result = type != null ? type.hashCode() : 0;
+		result = 31 * result + (name != null ? name.hashCode() : 0);
+		result = 31 * result + (filename != null ? filename.hashCode() : 0);
+		result = 31 * result + (charset != null ? charset.hashCode() : 0);
+		result = 31 * result + (size != null ? size.hashCode() : 0);
+		return result;
+	}
+
+	/**
+	 * Return the header value for this content disposition as defined in RFC 2183.
+	 * @see #parse(String)
+	 */
+	@Override
+	public String toString() {
+		StringBuilder builder = new StringBuilder(this.type);
+		if (this.name != null) {
+			builder.append("; name=\"");
+			builder.append(this.name).append('\"');
+		}
+		if (this.filename != null) {
+			if(this.charset == null || StandardCharsets.US_ASCII.equals(this.charset)) {
+				builder.append("; filename=\"");
+				builder.append(this.filename).append('\"');
+			}
+			else {
+				builder.append("; filename*=");
+				builder.append(encodeHeaderFieldParam(this.filename, this.charset));
+			}
+		}
+		if (this.size != null) {
+			builder.append("; size=");
+			builder.append(this.size);
+		}
+		return builder.toString();
+	}
+
+
+	/**
+	 * A mutable builder for {@code ContentDisposition}.
+	 */
+	public interface Builder {
+
+		/**
+		 * Set the value of the {@literal name} parameter
+		 */
+		Builder name(String name);
+
+		/**
+		 * Set the value of the {@literal filename} parameter
+		 */
+		Builder filename(String filename);
+
+		/**
+		 * Set the value of the {@literal filename*} that will be encoded as defined in
+		 * the RFC 5987. Only the US-ASCII, UTF-8 and ISO-8859-1 charsets are supported.
+		 */
+		Builder filename(String filename, Charset charset);
+
+		/**
+		 * Set the value of the {@literal size} parameter
+		 */
+		Builder size(Long size);
+
+		/**
+		 * Build the content disposition
+		 */
+		ContentDisposition build();
+
+	}
+
+	private static class BuilderImpl implements Builder {
+
+		private String type;
+
+		private String name;
+
+		private String filename;
+
+		private Charset charset;
+
+		private Long size;
+
+		public BuilderImpl(String type) {
+			Assert.hasText(type, "'type' must not be not empty");
+			this.type = type;
+		}
+
+		@Override
+		public Builder name(String name) {
+			this.name = name;
+			return this;
+		}
+
+		@Override
+		public Builder filename(String filename) {
+			this.filename = filename;
+			return this;
+		}
+
+		@Override
+		public Builder filename(String filename, Charset charset) {
+			this.filename = filename;
+			this.charset = charset;
+			return this;
+		}
+
+		@Override
+		public Builder size(Long size) {
+			this.size = size;
+			return this;
+		}
+
+		@Override
+		public ContentDisposition build() {
+			return new ContentDisposition(this.type, this.name, this.filename, this.charset, this.size);
+		}
+
+	}
+
+}