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Elasticsearch subproject :libs:elasticsearch-x-content
/*
* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
* or more contributor license agreements. Licensed under the Elastic License
* 2.0 and the Server Side Public License, v 1; you may not use this file except
* in compliance with, at your election, the Elastic License 2.0 or the Server
* Side Public License, v 1.
*/
package org.elasticsearch.xcontent;
import org.elasticsearch.xcontent.cbor.CborXContent;
import org.elasticsearch.xcontent.json.JsonXContent;
import org.elasticsearch.xcontent.smile.SmileXContent;
import org.elasticsearch.xcontent.yaml.YamlXContent;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
/**
* A one stop to use {@link org.elasticsearch.xcontent.XContent} and {@link XContentBuilder}.
*/
public class XContentFactory {
public static final int GUESS_HEADER_LENGTH = 20;
private XContentFactory() {}
/**
* Returns a content builder using JSON format ({@link org.elasticsearch.xcontent.XContentType#JSON}.
*/
public static XContentBuilder jsonBuilder() throws IOException {
return contentBuilder(XContentType.JSON);
}
/**
* Constructs a new json builder that will output the result into the provided output stream.
*/
public static XContentBuilder jsonBuilder(OutputStream os) throws IOException {
return new XContentBuilder(JsonXContent.jsonXContent, os);
}
/**
* Returns a content builder using SMILE format ({@link org.elasticsearch.xcontent.XContentType#SMILE}.
*/
public static XContentBuilder smileBuilder() throws IOException {
return contentBuilder(XContentType.SMILE);
}
/**
* Constructs a new json builder that will output the result into the provided output stream.
*/
public static XContentBuilder smileBuilder(OutputStream os) throws IOException {
return new XContentBuilder(SmileXContent.smileXContent, os);
}
/**
* Returns a content builder using YAML format ({@link org.elasticsearch.xcontent.XContentType#YAML}.
*/
public static XContentBuilder yamlBuilder() throws IOException {
return contentBuilder(XContentType.YAML);
}
/**
* Constructs a new yaml builder that will output the result into the provided output stream.
*/
public static XContentBuilder yamlBuilder(OutputStream os) throws IOException {
return new XContentBuilder(YamlXContent.yamlXContent, os);
}
/**
* Returns a content builder using CBOR format ({@link org.elasticsearch.xcontent.XContentType#CBOR}.
*/
public static XContentBuilder cborBuilder() throws IOException {
return contentBuilder(XContentType.CBOR);
}
/**
* Constructs a new cbor builder that will output the result into the provided output stream.
*/
public static XContentBuilder cborBuilder(OutputStream os) throws IOException {
return new XContentBuilder(CborXContent.cborXContent, os);
}
/**
* Constructs a xcontent builder that will output the result into the provided output stream.
*/
public static XContentBuilder contentBuilder(XContentType type, OutputStream outputStream) throws IOException {
XContentType canonical = type.canonical();
if (canonical == XContentType.JSON) {
return jsonBuilder(outputStream);
} else if (canonical == XContentType.SMILE) {
return smileBuilder(outputStream);
} else if (canonical == XContentType.YAML) {
return yamlBuilder(outputStream);
} else if (canonical == XContentType.CBOR) {
return cborBuilder(outputStream);
}
throw new IllegalArgumentException("No matching content type for " + type);
}
/**
* Returns a binary content builder for the provided content type.
*/
public static XContentBuilder contentBuilder(XContentType type) throws IOException {
XContentType canonical = type.canonical();
if (canonical == XContentType.JSON) {
return JsonXContent.contentBuilder();
} else if (canonical == XContentType.SMILE) {
return SmileXContent.contentBuilder();
} else if (canonical == XContentType.YAML) {
return YamlXContent.contentBuilder();
} else if (canonical == XContentType.CBOR) {
return CborXContent.contentBuilder();
}
throw new IllegalArgumentException("No matching content type for " + type);
}
/**
* Returns the {@link org.elasticsearch.xcontent.XContent} for the provided content type.
*/
public static XContent xContent(XContentType type) {
if (type == null) {
throw new IllegalArgumentException("Cannot get xcontent for unknown type");
}
return type.xContent();
}
/**
* Guesses the content type based on the provided char sequence.
*
* @deprecated the content type should not be guessed except for few cases where we effectively don't know the content type.
* The REST layer should move to reading the Content-Type header instead. There are other places where auto-detection may be needed.
* This method is deprecated to prevent usages of it from spreading further without specific reasons.
*/
@Deprecated
public static XContentType xContentType(CharSequence content) {
int length = content.length() < GUESS_HEADER_LENGTH ? content.length() : GUESS_HEADER_LENGTH;
if (length == 0) {
return null;
}
char first = content.charAt(0);
if (JsonXContent.jsonXContent.detectContent(content)) {
return XContentType.JSON;
}
// Should we throw a failure here? Smile idea is to use it in bytes....
if (SmileXContent.smileXContent.detectContent(content)) {
return XContentType.SMILE;
}
if (YamlXContent.yamlXContent.detectContent(content)) {
return XContentType.YAML;
}
// CBOR is not supported
// fallback for JSON
for (int i = 0; i < length; i++) {
char c = content.charAt(i);
if (c == '{') {
return XContentType.JSON;
}
if (Character.isWhitespace(c) == false) {
break;
}
}
return null;
}
/**
* Guesses the content (type) based on the provided char sequence and returns the corresponding {@link XContent}
*
* @deprecated the content type should not be guessed except for few cases where we effectively don't know the content type.
* The REST layer should move to reading the Content-Type header instead. There are other places where auto-detection may be needed.
* This method is deprecated to prevent usages of it from spreading further without specific reasons.
*/
@Deprecated
public static XContent xContent(CharSequence content) {
XContentType type = xContentType(content);
if (type == null) {
throw new XContentParseException("Failed to derive xcontent");
}
return xContent(type);
}
/**
* Guesses the content type based on the provided bytes and returns the corresponding {@link XContent}
*
* @deprecated the content type should not be guessed except for few cases where we effectively don't know the content type.
* The REST layer should move to reading the Content-Type header instead. There are other places where auto-detection may be needed.
* This method is deprecated to prevent usages of it from spreading further without specific reasons.
*/
@Deprecated
public static XContent xContent(byte[] data) {
return xContent(data, 0, data.length);
}
/**
* Guesses the content type based on the provided bytes and returns the corresponding {@link XContent}
*
* @deprecated guessing the content type should not be needed ideally. We should rather know the content type upfront or read it
* from headers. Till we fixed the REST layer to read the Content-Type header, that should be the only place where guessing is needed.
*/
@Deprecated
public static XContent xContent(byte[] data, int offset, int length) {
XContentType type = xContentType(data, offset, length);
if (type == null) {
throw new XContentParseException("Failed to derive xcontent");
}
return xContent(type);
}
/**
* Guesses the content type based on the provided input stream without consuming it.
*
* @deprecated the content type should not be guessed except for few cases where we effectively don't know the content type.
* The REST layer should move to reading the Content-Type header instead. There are other places where auto-detection may be needed.
* This method is deprecated to prevent usages of it from spreading further without specific reasons.
*/
@Deprecated
public static XContentType xContentType(InputStream si) throws IOException {
/*
* We need to guess the content type. To do this, we look for the first non-whitespace character and then try to guess the content
* type on the GUESS_HEADER_LENGTH bytes that follow. We do this in a way that does not modify the initial read position in the
* underlying input stream. This is why the input stream must support mark/reset and why we repeatedly mark the read position and
* reset.
*/
if (si.markSupported() == false) {
throw new IllegalArgumentException("Cannot guess the xcontent type without mark/reset support on " + si.getClass());
}
si.mark(Integer.MAX_VALUE);
try {
// scan until we find the first non-whitespace character or the end of the stream
int current;
do {
current = si.read();
if (current == -1) {
return null;
}
} while (Character.isWhitespace((char) current));
// now guess the content type off the next GUESS_HEADER_LENGTH bytes including the current byte
final byte[] firstBytes = new byte[GUESS_HEADER_LENGTH];
firstBytes[0] = (byte) current;
int read = 1;
while (read < GUESS_HEADER_LENGTH) {
final int r = si.read(firstBytes, read, GUESS_HEADER_LENGTH - read);
if (r == -1) {
break;
}
read += r;
}
return xContentType(firstBytes, 0, read);
} finally {
si.reset();
}
}
/**
* Guesses the content type based on the provided bytes.
*
* @deprecated the content type should not be guessed except for few cases where we effectively don't know the content type.
* The REST layer should move to reading the Content-Type header instead. There are other places where auto-detection may be needed.
* This method is deprecated to prevent usages of it from spreading further without specific reasons.
*/
@Deprecated
public static XContentType xContentType(byte[] bytes) {
return xContentType(bytes, 0, bytes.length);
}
/**
* Guesses the content type based on the provided bytes.
*
* @deprecated the content type should not be guessed except for few cases where we effectively don't know the content type.
* The REST layer should move to reading the Content-Type header instead. There are other places where auto-detection may be needed.
* This method is deprecated to prevent usages of it from spreading further without specific reasons.
*/
@Deprecated
public static XContentType xContentType(byte[] bytes, int offset, int length) {
int totalLength = bytes.length;
if (totalLength == 0 || length == 0) {
return null;
} else if ((offset + length) > totalLength) {
return null;
}
byte first = bytes[offset];
if (JsonXContent.jsonXContent.detectContent(bytes, offset, length)) {
return XContentType.JSON;
}
if (SmileXContent.smileXContent.detectContent(bytes, offset, length)) {
return XContentType.SMILE;
}
if (YamlXContent.yamlXContent.detectContent(bytes, offset, length)) {
return XContentType.YAML;
}
if (CborXContent.cborXContent.detectContent(bytes, offset, length)) {
return XContentType.CBOR;
}
// fallback for JSON
int jsonStart = 0;
// JSON may be preceded by UTF-8 BOM
if (length > 3 && first == (byte) 0xEF && bytes[offset + 1] == (byte) 0xBB && bytes[offset + 2] == (byte) 0xBF) {
jsonStart = 3;
}
// a last chance for JSON
for (int i = jsonStart; i < length; i++) {
byte b = bytes[offset + i];
if (b == '{') {
return XContentType.JSON;
}
if (Character.isWhitespace(b) == false) {
break;
}
}
return null;
}
}