Http Multipart enables POSTing of several files in one go. I didn’t found any good supported way of doing this from Android so I created some helpers for achieving this.
The Multipart is quite strange (ugly) protocol. See reference for more details.
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public class MultiParts { private final static String CRLF = "\r\n"; private final static String DASHES = "--"; private final static String CONTENT_TYPE = "Content-Type: "; private final static String FORM_DATA = "Content-Disposition: form-data; "; private final static String NAME = "name="; private final static String FILENAME = "; filename="; private final static String QUOTE = "\""; public static final String FILES_START = "files["; public static final String FILES_END = "]"; private final List<MultiParts.Part> parts = new ArrayList<MultiParts.Part>(); private final String boundary = UUID.randomUUID().toString(); public byte[] encode() throws IOException { ByteArrayOutputStream out = new ByteArrayOutputStream(); DataOutputStream dout = new DataOutputStream(out); dout.writeBytes(DASHES); dout.writeBytes(getBoundary()); dout.writeBytes(CRLF); Iterator<MultiParts.Part> it = parts.iterator(); while (it.hasNext()) { MultiParts.Part part = it.next(); part.writeTo(dout); if (it.hasNext()) { dout.writeBytes(CRLF); } } dout.writeBytes(DASHES); dout.writeBytes(CRLF); return out.toByteArray(); } public static MultiParts.PartBuilder newMultiParts() { return new MultiParts.PartBuilder(); } public String getBoundary() { return boundary; } // ---------------------------------------- public static final class PartBuilder { private MultiParts multi = new MultiParts(); public MultiParts.PartBuilder addBinary(String key, byte [] data, String type) throws IOException { multi.parts.add(new MultiParts.FilePart(multi.getBoundary(), key, data, type)); return this; } public MultiParts.PartBuilder addFile(String key, File file, String type) throws IOException { ByteArrayOutputStream out = new ByteArrayOutputStream(); FileInputStream ins = new FileInputStream(file); pipe(ins, out); addBinary(key, out.toByteArray(), type); return this; } public MultiParts.PartBuilder add(String key, String str) throws UnsupportedEncodingException { multi.parts.add(new MultiParts.StringPart(multi.getBoundary(), key, str.getBytes("UTF-8"), "text/plain; charset=utf-8")); return this; } public MultiParts.PartBuilder addHtml(String key, String str) throws UnsupportedEncodingException { multi.parts.add(new MultiParts.StringPart(multi.getBoundary(), key, str.getBytes("UTF-8"), "text/html; charset=utf-8")); return this; } public MultiParts build() { return multi; } private void pipe(InputStream is, OutputStream os) throws IOException { int n; byte[] buffer = new byte[1024]; while ((n = is.read(buffer)) > -1) { os.write(buffer, 0, n); } is.close(); os.close(); } } public static final class FilePart extends MultiParts.Part { private FilePart(String boundary, String name, byte[] data, String type) { super(boundary, name, data, type); } @Override protected void writeContentType(DataOutputStream dout) throws IOException { dout.writeBytes(type); } @Override protected void writeContentDisposition(DataOutputStream dout) throws IOException { dout.writeBytes(NAME); dout.writeBytes(QUOTE); dout.writeBytes(FILES_START); dout.writeBytes(name); dout.writeBytes(FILES_END); dout.writeBytes(QUOTE); dout.writeBytes(FILENAME); dout.writeBytes(QUOTE); dout.writeBytes(name); dout.writeBytes(QUOTE); } } public static final class StringPart extends MultiParts.Part { private StringPart(String boundary, String name, byte[] data, String type) { super(boundary, name, data, type); } @Override protected void writeContentDisposition(DataOutputStream dout) throws IOException { dout.writeBytes(NAME); dout.writeBytes(QUOTE); dout.writeBytes(name); dout.writeBytes(QUOTE); } } public static abstract class Part { protected String name; protected byte[] data; protected String type; protected String boundary; private Part(String boundary, String name, byte[] data, String type) { super(); this.boundary = boundary; this.name = name; this.data = data; this.type = type; } protected void writeContentType(DataOutputStream dout) throws IOException { dout.writeBytes(type); } protected void writeContentDisposition(DataOutputStream dout) throws IOException { } public String getName() { return name; } public byte[] getData() { return data; } public String getType() { return type; } public void writeTo(DataOutputStream dout) throws IOException { dout.writeBytes(FORM_DATA); writeContentDisposition(dout); dout.writeBytes(CRLF); dout.writeBytes(CONTENT_TYPE); writeContentType(dout); dout.writeBytes(CRLF); dout.writeBytes(CRLF); dout.write(data); dout.writeBytes(CRLF); dout.writeBytes(DASHES); dout.writeBytes(boundary); } } } |
An Enum that keeps supported formats. Add which ever you need.
The Enum contains the Http Mime type and the file extension.
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public enum MimeType { PNG("image/png", ".png"), JPG("image/jpg", ".jpg"), JPEG("image/jpeg", ".jpeg"), GIF("image/gif", ".gif"), BINARY("application/octet-stream", "*"); private final String extension; private final String type; private MimeType(String type, String extension) { this.type = type; this.extension = extension; } public String getExtension() { return extension; } public String getType() { return type; } public static MimeType fromName(String name) { MimeType result = MimeType.BINARY; String str = name.toLowerCase(); for(MimeType mime : values()) { if(str.endsWith(mime.getExtension())) { result = mime; break; } } return result; } } |
The HttpUtil.java wraps things up and integrate with Internet 😉
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public class HttpUtil { public static final String USER_AGENT = "Mozilla/5.0"; public static String post(String url, MultiParts parts) throws IOException { HttpURLConnection conn = prepareConnection(url); conn.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + parts.getBoundary()); return postData(conn, parts.encode()); } public static String post(String url, String content, String encoding) throws IOException { HttpURLConnection conn = prepareConnection(url); return postData(conn, content.getBytes(encoding)); } public static String post(String url, byte[] data) throws IOException { HttpURLConnection conn = prepareConnection(url); return postData(conn, data); } private static String postData(HttpURLConnection con, byte[] bytes) throws IOException { writeBytes(con, bytes); int responseCode = con.getResponseCode(); if (responseCode != 200) { throw new IOException("Response code: " + responseCode); } String result = readString(con); return result; } private static HttpURLConnection prepareConnection(String url) throws IOException { HttpURLConnection conn; String lowerUrl = url.toLowerCase(); if (lowerUrl.startsWith("https")) { conn = prepareHttps(url); } else if (lowerUrl.startsWith("http")) { conn = prepareHttp(url); } else { throw new IllegalArgumentException("Only protocol HTTP or HTTPS is allowed"); } return conn; } private static HttpsURLConnection prepareHttps(String url) throws IOException { URL obj = new URL(url); HttpsURLConnection con = (HttpsURLConnection) obj.openConnection(); preparePost(con); return con; } private static HttpURLConnection prepareHttp(String url) throws IOException { URL obj = new URL(url); HttpURLConnection con = (HttpURLConnection) obj.openConnection(); preparePost(con); return con; } private static void writeBytes(HttpURLConnection con, byte[] bytes) throws IOException { DataOutputStream wr = null; try { wr = new DataOutputStream(con.getOutputStream()); wr.write(bytes); wr.flush(); } finally { if (wr != null) { wr.close(); } } } private static String readString(HttpURLConnection con) throws IOException { StringBuffer response = new StringBuffer(); BufferedReader in = null; try { in = new BufferedReader(new InputStreamReader(con.getInputStream())); String inputLine; while ((inputLine = in.readLine()) != null) { response.append(inputLine); } } finally { if (in != null) { in.close(); } } return response.toString(); } private static void preparePost(HttpURLConnection con) throws ProtocolException { con.setRequestMethod("POST"); con.setRequestProperty("User-Agent", USER_AGENT); con.setRequestProperty("Accept-Language", "en-US,en;q=0.5"); con.setDoOutput(true); } } |