com.google.gerrit.extensions.restapi.BinaryResult Maven / Gradle / Ivy
// Copyright (C) 2012 The Android Open Source Project
//
// 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 com.google.gerrit.extensions.restapi;
import static java.nio.charset.StandardCharsets.UTF_8;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.io.ByteArrayOutputStream;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.nio.charset.CodingErrorAction;
import java.nio.charset.UnsupportedCharsetException;
/**
* Wrapper around a non-JSON result from a {@link RestView}.
*
* Views may return this type to signal they want the server glue to write raw data to the
* client, instead of attempting automatic conversion to JSON. The create form is overloaded to
* handle plain text from a String, or binary data from a {@code byte[]} or {@code InputSteam}.
*/
public abstract class BinaryResult implements Closeable {
/** Default MIME type for unknown binary data. */
static final String OCTET_STREAM = "application/octet-stream";
/** Produce a UTF-8 encoded result from a string. */
public static BinaryResult create(String data) {
return new StringResult(data);
}
/** Produce an {@code application/octet-stream} result from a byte array. */
public static BinaryResult create(byte[] data) {
return new Array(data);
}
/**
* Produce an {@code application/octet-stream} of unknown length by copying the InputStream until
* EOF. The server glue will automatically close this stream when copying is complete.
*/
public static BinaryResult create(InputStream data) {
return new Stream(data);
}
private String contentType = OCTET_STREAM;
private Charset characterEncoding;
private long contentLength = -1;
private boolean gzip = true;
private boolean base64;
private String attachmentName;
/** Returns the MIME type of the result, for HTTP clients. */
public String getContentType() {
Charset enc = getCharacterEncoding();
if (enc != null) {
return contentType + "; charset=" + enc.name();
}
return contentType;
}
/** Set the MIME type of the result, and return {@code this}. */
@CanIgnoreReturnValue
public BinaryResult setContentType(String contentType) {
this.contentType = contentType != null ? contentType : OCTET_STREAM;
return this;
}
/** Get the character encoding; null if not known. */
public Charset getCharacterEncoding() {
return characterEncoding;
}
/** Set the character set used to encode text data and return {@code this}. */
@CanIgnoreReturnValue
public BinaryResult setCharacterEncoding(Charset encoding) {
characterEncoding = encoding;
return this;
}
/** Get the attachment file name; null if not set. */
public String getAttachmentName() {
return attachmentName;
}
/** Set the attachment file name and return {@code this}. */
@CanIgnoreReturnValue
public BinaryResult setAttachmentName(String attachmentName) {
this.attachmentName = attachmentName;
return this;
}
/** Returns length in bytes of the result; -1 if not known. */
public long getContentLength() {
return contentLength;
}
/** Set the content length of the result; -1 if not known. */
@CanIgnoreReturnValue
public BinaryResult setContentLength(long len) {
this.contentLength = len;
return this;
}
/** Returns true if this result can be gzip compressed to clients. */
public boolean canGzip() {
return gzip;
}
/** Disable gzip compression for already compressed responses. */
@CanIgnoreReturnValue
public BinaryResult disableGzip() {
this.gzip = false;
return this;
}
/** Returns true if the result must be base64 encoded. */
public boolean isBase64() {
return base64;
}
/** Wrap the binary data in base64 encoding. */
@CanIgnoreReturnValue
public BinaryResult base64() {
base64 = true;
return this;
}
/**
* Write or copy the result onto the specified output stream.
*
* @param os stream to write result data onto. This stream will be closed by the caller after this
* method returns.
* @throws IOException if the data cannot be produced, or the OutputStream {@code os} throws any
* IOException during a write or flush call.
*/
public abstract void writeTo(OutputStream os) throws IOException;
/**
* Return a copy of the result as a String.
*
*
The default version of this method copies the result into a temporary byte array and then
* tries to decode it using the configured encoding.
*
* @return string version of the result.
* @throws IOException if the data cannot be produced or could not be decoded to a String.
*/
public String asString() throws IOException {
long len = getContentLength();
ByteArrayOutputStream buf;
if (0 < len) {
buf = new ByteArrayOutputStream((int) len);
} else {
buf = new ByteArrayOutputStream();
}
writeTo(buf);
return decode(buf.toByteArray(), getCharacterEncoding());
}
/** Close the result and release any resources it holds. */
@Override
public void close() throws IOException {}
@Override
public String toString() {
if (getContentLength() >= 0) {
return String.format(
"BinaryResult[Content-Type: %s, Content-Length: %d]",
getContentType(), getContentLength());
}
return String.format(
"BinaryResult[Content-Type: %s, Content-Length: unknown]", getContentType());
}
private static String decode(byte[] data, Charset enc) {
try {
Charset cs = enc != null ? enc : UTF_8;
return cs.newDecoder()
.onMalformedInput(CodingErrorAction.REPORT)
.onUnmappableCharacter(CodingErrorAction.REPORT)
.decode(ByteBuffer.wrap(data))
.toString();
} catch (UnsupportedCharsetException | CharacterCodingException e) {
// Fallback to ISO-8850-1 style encoding.
StringBuilder r = new StringBuilder(data.length);
for (byte b : data) {
r.append((char) (b & 0xff));
}
return r.toString();
}
}
private static class Array extends BinaryResult {
private final byte[] data;
Array(byte[] data) {
this.data = data;
setContentLength(data.length);
}
@Override
public void writeTo(OutputStream os) throws IOException {
os.write(data);
}
@Override
public String asString() {
return decode(data, getCharacterEncoding());
}
}
private static class StringResult extends Array {
private final String str;
StringResult(String str) {
super(str.getBytes(UTF_8));
setContentType("text/plain");
setCharacterEncoding(UTF_8);
this.str = str;
}
@Override
public String asString() {
return str;
}
}
private static class Stream extends BinaryResult {
private final InputStream src;
Stream(InputStream src) {
this.src = src;
}
@Override
public void writeTo(OutputStream dst) throws IOException {
byte[] tmp = new byte[4096];
int n;
while (0 < (n = src.read(tmp))) {
dst.write(tmp, 0, n);
}
}
@Override
public void close() throws IOException {
src.close();
}
}
}