Java tutorial
/** * The MIT License * Copyright (c) 2015 Estonian Information System Authority (RIA), Population Register Centre (VRK) * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ package ee.ria.xroad.common.util; import static ee.ria.xroad.common.util.MimeUtils.randomBoundary; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.nio.charset.StandardCharsets; import java.util.Stack; import org.apache.commons.io.IOUtils; import lombok.extern.slf4j.Slf4j; /** * Writes multipart content into a output stream. */ @Slf4j public class MultipartEncoder implements AutoCloseable { private static final byte[] CRLF = { '\r', '\n' }; private static final byte[] DASHDASH = { '-', '-' }; protected final Stack<String> parts = new Stack<>(); protected final String topBoundary; protected final OutputStream out; protected boolean inPart = false; /** * Constructs a new multipart encoder with the given output stream. * @param out the output stream into which this encoder should write */ public MultipartEncoder(OutputStream out) { this(out, randomBoundary()); } /** * Constructs a new multipart encoder with the given output stream * and using the provided top-level boundary. * @param out the output stream into which this encoder should write * @param topBoundary the top-level boundary that should be used */ public MultipartEncoder(OutputStream out, String topBoundary) { this.out = out; this.topBoundary = topBoundary; parts.add(topBoundary); } /** * @return content type for the encoded message. */ public String getContentType() { return MimeUtils.mpMixedContentType(topBoundary); } /** * @return top-level boundary. */ public String getBoundary() { return topBoundary; } /** * Begins a nested section with a random boundary. * @throws IOException in case an I/O error occurred */ public void startNested() throws IOException { startNested(randomBoundary()); } /** * Begins a nested section with the specified boundary. * @param boundary the boundary that should be used for this section * @throws IOException in case an I/O error occurred */ public void startNested(String boundary) throws IOException { startPart(MimeUtils.mpMixedContentType(boundary)); parts.add(boundary); } /** * Begins a nested section with the specified boundary and headers. * @param boundary the boundary that should be used for this section * @param headers headers that should be appended to the start of this section * @throws IOException in case an I/O error occurred */ public void startNested(String boundary, String[] headers) throws IOException { startPart(MimeUtils.mpMixedContentType(boundary), headers); parts.add(boundary); } /** * Ends the current nested section. * @throws IOException in case an I/O error occurred */ public void endNested() throws IOException { String currentBoundary = parts.pop(); if (currentBoundary != null) { out.write(CRLF); out.write(DASHDASH); writeString(currentBoundary); out.write(DASHDASH); out.write(CRLF); } } /** * Starts new MIME part. Use write() method to write content of the part. * @param contentType content type of this MIME part * @throws IOException in case an I/O error occurred */ public void startPart(String contentType) throws IOException { startPart(contentType, null); } /** * Starts new MIME part. Use write() method to write content of the part. * @param contentType content type of this MIME part * @param headers headers that should be appended to the start of this MIME part * @throws IOException in case an I/O error occurred */ public void startPart(String contentType, String[] headers) throws IOException { writeCurrentBoundary(); if (contentType != null) { writeString(MimeUtils.HEADER_CONTENT_TYPE + ": " + contentType); out.write(CRLF); } for (int i = 0; headers != null && i < headers.length; i++) { writeString(headers[i]); out.write(CRLF); } out.write(CRLF); } /** * Assumes that content contains already encoded MIME part * (header + body). It then writes the whole part in one operation. * @param content input stream containing raw MIME part content * @throws IOException in case an I/O error occurred */ public void writeRawPart(InputStream content) throws IOException { writeCurrentBoundary(); write(content); } /** * Writes the given bytes into the encoder's output stream. * @param content byte content to write * @throws IOException in case an I/O error occurred */ public void write(byte[] content) throws IOException { out.write(content); } /** * Writes the content of the given input stream into the encoder's output stream. * @param content input stream containing the content to write * @throws IOException in case an I/O error occurred */ public void write(InputStream content) throws IOException { IOUtils.copy(content, out); } @Override public void close() throws IOException { while (!parts.isEmpty()) { endNested(); } try { out.flush(); } catch (IOException ignored) { //ignore log.error("Error flushing multipart encoder stream", ignored); } out.close(); } private void writeCurrentBoundary() throws IOException { if (inPart) { // Write CRLF to ensure that the boundary starts on new line. out.write(CRLF); } inPart = true; String boundary = parts.peek(); out.write(DASHDASH); writeString(boundary); out.write(CRLF); } private void writeString(String string) throws IOException { out.write(string.getBytes(StandardCharsets.ISO_8859_1)); } }