Struts example source code file (PropertiesReader.java)
The Struts PropertiesReader.java source code/*
* 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 com.opensymphony.xwork2.util;
import java.io.*;
import java.util.ArrayList;
import java.util.List;
/**
* 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.
*
* This class was pulled out of Jakarta Commons Configuration and
* Jakarta Commons Lang trunk revision 476093
*/
public class PropertiesReader extends LineNumberReader
{
/** Stores the comment lines for the currently processed property.*/
private 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 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 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<String>();
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.length() < 1 || 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><value>)
*
* @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) or whether further properties are
* available (<b>true).
*
* @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()
* @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()} was invoked and its
* return value was <b>true.
*
* @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()} was invoked and
* its return value was <b>true.
*
* @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
Other Struts examples (source code examples)Here is a short list of links related to this Struts PropertiesReader.java source code file: |
The search page
Other Struts source code examples at this package level
Click here to learn more about this project
