spring HtmlCharacterEntityDecoder 源码

spring HtmlCharacterEntityDecoder 代码

文件路径：/spring-web/src/main/java/org/springframework/web/util/HtmlCharacterEntityDecoder.java

/*
 * Copyright 2002-2021 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
 *
 *      https://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.web.util;

/**
 * Helper for decoding HTML Strings by replacing character
 * entity references with the referred character.
 *
 * @author Juergen Hoeller
 * @author Martin Kersten
 * @since 1.2.1
 */
class HtmlCharacterEntityDecoder {

	private static final int MAX_REFERENCE_SIZE = 10;


	private final HtmlCharacterEntityReferences characterEntityReferences;

	private final String originalMessage;

	private final StringBuilder decodedMessage;

	private int currentPosition = 0;

	private int nextPotentialReferencePosition = -1;

	private int nextSemicolonPosition = -2;


	public HtmlCharacterEntityDecoder(HtmlCharacterEntityReferences characterEntityReferences, String original) {
		this.characterEntityReferences = characterEntityReferences;
		this.originalMessage = original;
		this.decodedMessage = new StringBuilder(original.length());
	}


	public String decode() {
		while (this.currentPosition < this.originalMessage.length()) {
			findNextPotentialReference(this.currentPosition);
			copyCharactersTillPotentialReference();
			processPossibleReference();
		}
		return this.decodedMessage.toString();
	}

	private void findNextPotentialReference(int startPosition) {
		this.nextPotentialReferencePosition = Math.max(startPosition, this.nextSemicolonPosition - MAX_REFERENCE_SIZE);

		do {
			this.nextPotentialReferencePosition =
					this.originalMessage.indexOf('&', this.nextPotentialReferencePosition);

			if (this.nextSemicolonPosition != -1 &&
					this.nextSemicolonPosition < this.nextPotentialReferencePosition) {
				this.nextSemicolonPosition = this.originalMessage.indexOf(';', this.nextPotentialReferencePosition + 1);
			}

			if (this.nextPotentialReferencePosition == -1) {
				break;
			}
			if (this.nextSemicolonPosition == -1) {
				this.nextPotentialReferencePosition = -1;
				break;
			}
			if (this.nextSemicolonPosition - this.nextPotentialReferencePosition < MAX_REFERENCE_SIZE) {
				break;
			}

			this.nextPotentialReferencePosition = this.nextPotentialReferencePosition + 1;
		}
		while (this.nextPotentialReferencePosition != -1);
	}

	private void copyCharactersTillPotentialReference() {
		if (this.nextPotentialReferencePosition != this.currentPosition) {
			int skipUntilIndex = (this.nextPotentialReferencePosition != -1 ?
					this.nextPotentialReferencePosition : this.originalMessage.length());
			if (skipUntilIndex - this.currentPosition > 3) {
				this.decodedMessage.append(this.originalMessage, this.currentPosition, skipUntilIndex);
				this.currentPosition = skipUntilIndex;
			}
			else {
				while (this.currentPosition < skipUntilIndex) {
					this.decodedMessage.append(this.originalMessage.charAt(this.currentPosition++));
				}
			}
		}
	}

	private void processPossibleReference() {
		if (this.nextPotentialReferencePosition != -1) {
			boolean isNumberedReference = (this.originalMessage.charAt(this.currentPosition + 1) == '#');
			boolean wasProcessable = isNumberedReference ? processNumberedReference() : processNamedReference();
			if (wasProcessable) {
				this.currentPosition = this.nextSemicolonPosition + 1;
			}
			else {
				char currentChar = this.originalMessage.charAt(this.currentPosition);
				this.decodedMessage.append(currentChar);
				this.currentPosition++;
			}
		}
	}

	private boolean processNumberedReference() {
		char referenceChar = this.originalMessage.charAt(this.nextPotentialReferencePosition + 2);
		boolean isHexNumberedReference = (referenceChar == 'x' || referenceChar == 'X');
		try {
			int value = (!isHexNumberedReference ?
					Integer.parseInt(getReferenceSubstring(2)) :
					Integer.parseInt(getReferenceSubstring(3), 16));
			this.decodedMessage.append((char) value);
			return true;
		}
		catch (NumberFormatException ex) {
			return false;
		}
	}

	private boolean processNamedReference() {
		String referenceName = getReferenceSubstring(1);
		char mappedCharacter = this.characterEntityReferences.convertToCharacter(referenceName);
		if (mappedCharacter != HtmlCharacterEntityReferences.CHAR_NULL) {
			this.decodedMessage.append(mappedCharacter);
			return true;
		}
		return false;
	}

	private String getReferenceSubstring(int referenceOffset) {
		return this.originalMessage.substring(
				this.nextPotentialReferencePosition + referenceOffset, this.nextSemicolonPosition);
	}

}

相关信息

spring 源码目录

相关文章

spring ContentCachingRequestWrapper 源码

spring ContentCachingResponseWrapper 源码

spring CookieGenerator 源码

spring DefaultUriBuilderFactory 源码

spring HierarchicalUriComponents 源码

spring HtmlCharacterEntityReferences 源码

spring HtmlUtils 源码

spring HttpSessionMutexListener 源码

spring IntrospectorCleanupListener 源码

spring JavaScriptUtils 源码