PropertiesReader.java
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.struts2.util;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import java.io.IOException;
import java.io.LineNumberReader;
import java.io.Reader;
import java.io.StringWriter;
import java.io.Writer;
import java.util.ArrayList;
import java.util.List;
/**
* <p>
* This class is used to read properties lines. These lines do
* not terminate with new-line chars but rather when there is no
* backslash sign a the end of the line. This is used to
* concatenate multiple lines for readability.
* </p>
*
* <p>
* This class was pulled out of Jakarta Commons Configuration and
* Jakarta Commons Lang trunk revision 476093
* </p>
*/
public class PropertiesReader extends LineNumberReader {
private static final Logger LOG = LogManager.getLogger(PropertiesReader.class);
/**
* Stores the comment lines for the currently processed property.
*/
private final List<String> commentLines;
/**
* Stores the name of the last read property.
*/
private String propertyName;
/**
* Stores the value of the last read property.
*/
private String propertyValue;
/**
* Stores the list delimiter character.
*/
private final char delimiter;
/**
* Constant for the supported comment characters.
*/
static final String COMMENT_CHARS = "#!";
/**
* Constant for the radix of hex numbers.
*/
private static final int HEX_RADIX = 16;
/**
* Constant for the length of a unicode literal.
*/
private static final int UNICODE_LEN = 4;
/**
* The list of possible key/value separators
*/
private static final char[] SEPARATORS = new char[]{'=', ':'};
/**
* The white space characters used as key/value separators.
*/
private static final char[] WHITE_SPACE = new char[]{' ', '\t', '\f'};
/**
* Constructor.
*
* @param reader A Reader.
*/
public PropertiesReader(Reader reader) {
this(reader, ',');
}
/**
* Creates a new instance of <code>PropertiesReader</code> and sets
* the underlaying reader and the list delimiter.
*
* @param reader the reader
* @param listDelimiter the list delimiter character
* @since 1.3
*/
public PropertiesReader(Reader reader, char listDelimiter) {
super(reader);
commentLines = new ArrayList<>();
delimiter = listDelimiter;
}
/**
* Tests whether a line is a comment, i.e. whether it starts with a comment
* character.
*
* @param line the line
* @return a flag if this is a comment line
* @since 1.3
*/
boolean isCommentLine(String line) {
String s = line.trim();
// blanc lines are also treated as comment lines
return s.isEmpty() || COMMENT_CHARS.indexOf(s.charAt(0)) >= 0;
}
/**
* Reads a property line. Returns null if Stream is
* at EOF. Concatenates lines ending with "\".
* Skips lines beginning with "#" or "!" and empty lines.
* The return value is a property definition (<code><name></code>
* = <code><value></code>)
*
* @return A string containing a property value or null
* @throws IOException in case of an I/O error
*/
public String readProperty() throws IOException {
commentLines.clear();
StringBuilder buffer = new StringBuilder();
while (true) {
String line = readLine();
if (line == null) {
// EOF
return null;
}
if (isCommentLine(line)) {
commentLines.add(line);
continue;
}
line = line.trim();
if (checkCombineLines(line)) {
line = line.substring(0, line.length() - 1);
buffer.append(line);
} else {
buffer.append(line);
break;
}
}
return buffer.toString();
}
/**
* Parses the next property from the input stream and stores the found
* name and value in internal fields. These fields can be obtained using
* the provided getter methods. The return value indicates whether EOF
* was reached (<b>false</b>) or whether further properties are
* available (<b>true</b>).
*
* @return a flag if further properties are available
* @throws IOException if an error occurs
* @since 1.3
*/
public boolean nextProperty() throws IOException {
String line = readProperty();
if (line == null) {
return false; // EOF
}
// parse the line
String[] property = parseProperty(line);
propertyName = unescapeJava(property[0]);
propertyValue = unescapeJava(property[1], delimiter);
return true;
}
/**
* Returns the comment lines that have been read for the last property.
*
* @return the comment lines for the last property returned by
* <code>readProperty()</code>
* @since 1.3
*/
public List<String> getCommentLines() {
return commentLines;
}
/**
* Returns the name of the last read property. This method can be called
* after <code>{@link #nextProperty()}</code> was invoked and its
* return value was <b>true</b>.
*
* @return the name of the last read property
* @since 1.3
*/
public String getPropertyName() {
return propertyName;
}
/**
* Returns the value of the last read property. This method can be
* called after <code>{@link #nextProperty()}</code> was invoked and
* its return value was <b>true</b>.
*
* @return the value of the last read property
* @since 1.3
*/
public String getPropertyValue() {
return propertyValue;
}
/**
* Checks if the passed in line should be combined with the following.
* This is true, if the line ends with an odd number of backslashes.
*
* @param line the line
* @return a flag if the lines should be combined
*/
private boolean checkCombineLines(String line) {
int bsCount = 0;
for (int idx = line.length() - 1; idx >= 0 && line.charAt(idx) == '\\'; idx--) {
bsCount++;
}
return bsCount % 2 == 1;
}
/**
* Parse a property line and return the key and the value in an array.
*
* @param line the line to parse
* @return an array with the property's key and value
* @since 1.2
*/
private String[] parseProperty(String line) {
// sorry for this spaghetti code, please replace it as soon as
// possible with a regexp when the Java 1.3 requirement is dropped
String[] result = new String[2];
StringBuilder key = new StringBuilder();
StringBuilder value = new StringBuilder();
// state of the automaton:
// 0: key parsing
// 1: antislash found while parsing the key
// 2: separator crossing
// 3: value parsing
int state = 0;
for (int pos = 0; pos < line.length(); pos++) {
char c = line.charAt(pos);
switch (state) {
case 0:
if (c == '\\') {
state = 1;
} else if (contains(WHITE_SPACE, c)) {
// switch to the separator crossing state
state = 2;
} else if (contains(SEPARATORS, c)) {
// switch to the value parsing state
state = 3;
} else {
key.append(c);
}
break;
case 1:
if (contains(SEPARATORS, c) || contains(WHITE_SPACE, c)) {
// this is an escaped separator or white space
key.append(c);
} else {
// another escaped character, the '\' is preserved
key.append('\\');
key.append(c);
}
// return to the key parsing state
state = 0;
break;
case 2:
if (contains(WHITE_SPACE, c)) {
// do nothing, eat all white spaces
state = 2;
} else if (contains(SEPARATORS, c)) {
// switch to the value parsing state
state = 3;
} else {
// any other character indicates we encoutered the beginning of the value
value.append(c);
// switch to the value parsing state
state = 3;
}
break;
case 3:
value.append(c);
break;
}
}
result[0] = key.toString().trim();
result[1] = value.toString().trim();
return result;
}
/**
* <p>Unescapes any Java literals found in the <code>String</code> to a
* <code>Writer</code>.</p> This is a slightly modified version of the
* StringEscapeUtils.unescapeJava() function in commons-lang that doesn't
* drop escaped separators (i.e '\,').
*
* @param str the <code>String</code> to unescape, may be null
* @param delimiter the delimiter for multi-valued properties
* @return the processed string
* @throws IllegalArgumentException if the Writer is <code>null</code>
*/
protected static String unescapeJava(String str, char delimiter) {
if (str == null) {
return null;
}
int sz = str.length();
StringBuilder out = new StringBuilder(sz);
StringBuilder unicode = new StringBuilder(UNICODE_LEN);
boolean hadSlash = false;
boolean inUnicode = false;
for (int i = 0; i < sz; i++) {
char ch = str.charAt(i);
if (inUnicode) {
// if in unicode, then we're reading unicode
// values in somehow
unicode.append(ch);
if (unicode.length() == UNICODE_LEN) {
// unicode now contains the four hex digits
// which represents our unicode character
try {
int value = Integer.parseInt(unicode.toString(), HEX_RADIX);
out.append((char) value);
unicode.setLength(0);
inUnicode = false;
hadSlash = false;
} catch (NumberFormatException nfe) {
throw new RuntimeException("Unable to parse unicode value: " + unicode, nfe);
}
}
continue;
}
if (hadSlash) {
// handle an escaped value
hadSlash = false;
if (ch == '\\') {
out.append('\\');
} else if (ch == '\'') {
out.append('\'');
} else if (ch == '\"') {
out.append('"');
} else if (ch == 'r') {
out.append('\r');
} else if (ch == 'f') {
out.append('\f');
} else if (ch == 't') {
out.append('\t');
} else if (ch == 'n') {
out.append('\n');
} else if (ch == 'b') {
out.append('\b');
} else if (ch == delimiter) {
out.append('\\');
out.append(delimiter);
} else if (ch == 'u') {
// uh-oh, we're in unicode country....
inUnicode = true;
} else {
out.append(ch);
}
continue;
} else if (ch == '\\') {
hadSlash = true;
continue;
}
out.append(ch);
}
if (hadSlash) {
// then we're in the weird case of a \ at the end of the
// string, let's output it anyway.
out.append('\\');
}
return out.toString();
}
/**
* <p>Checks if the object is in the given array.</p>
*
* <p>The method returns <code>false</code> if a <code>null</code> array is passed in.</p>
*
* @param array the array to search through
* @param objectToFind the object to find
* @return <code>true</code> if the array contains the object
*/
public boolean contains(char[] array, char objectToFind) {
if (array == null) {
return false;
}
for (char anArray : array) {
if (objectToFind == anArray) {
return true;
}
}
return false;
}
/**
* <p>Unescapes any Java literals found in the <code>String</code>.
* For example, it will turn a sequence of <code>'\'</code> and
* <code>'n'</code> into a newline character, unless the <code>'\'</code>
* is preceded by another <code>'\'</code>.</p>
*
* @param str the <code>String</code> to unescape, may be null
* @return a new unescaped <code>String</code>, <code>null</code> if null string input
*/
public static String unescapeJava(String str) {
if (str == null) {
return null;
}
try {
StringWriter writer = new StringWriter(str.length());
unescapeJava(writer, str);
return writer.toString();
} catch (IOException ioe) {
// this should never ever happen while writing to a StringWriter
LOG.warn("Call to unescape java string failed!", ioe);
return null;
}
}
/**
* <p>Unescapes any Java literals found in the <code>String</code> to a
* <code>Writer</code>.</p>
*
* <p>For example, it will turn a sequence of <code>'\'</code> and
* <code>'n'</code> into a newline character, unless the <code>'\'</code>
* is preceded by another <code>'\'</code>.</p>
*
* <p>A <code>null</code> string input has no effect.</p>
*
* @param out the <code>Writer</code> used to output unescaped characters
* @param str the <code>String</code> to unescape, may be null
* @throws IllegalArgumentException if the Writer is <code>null</code>
* @throws IOException if error occurs on underlying Writer
*/
public static void unescapeJava(Writer out, String str) throws IOException {
if (out == null) {
throw new IllegalArgumentException("The Writer must not be null");
}
if (str == null) {
return;
}
int sz = str.length();
StringBuilder unicode = new StringBuilder(4);
boolean hadSlash = false;
boolean inUnicode = false;
for (int i = 0; i < sz; i++) {
char ch = str.charAt(i);
if (inUnicode) {
// if in unicode, then we're reading unicode
// values in somehow
unicode.append(ch);
if (unicode.length() == 4) {
// unicode now contains the four hex digits
// which represents our unicode character
try {
int value = Integer.parseInt(unicode.toString(), 16);
out.write((char) value);
unicode.setLength(0);
inUnicode = false;
hadSlash = false;
} catch (NumberFormatException nfe) {
throw new RuntimeException("Unable to parse unicode value: " + unicode, nfe);
}
}
continue;
}
if (hadSlash) {
// handle an escaped value
hadSlash = false;
switch (ch) {
case '\\':
out.write('\\');
break;
case '\'':
out.write('\'');
break;
case '\"':
out.write('"');
break;
case 'r':
out.write('\r');
break;
case 'f':
out.write('\f');
break;
case 't':
out.write('\t');
break;
case 'n':
out.write('\n');
break;
case 'b':
out.write('\b');
break;
case 'u': {
// uh-oh, we're in unicode country....
inUnicode = true;
break;
}
default:
out.write(ch);
break;
}
continue;
} else if (ch == '\\') {
hadSlash = true;
continue;
}
out.write(ch);
}
if (hadSlash) {
// then we're in the weird case of a \ at the end of the
// string, let's output it anyway.
out.write('\\');
}
}
}