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International Component for Unicode for Java (ICU4J) is a mature, widely used Java library
providing Unicode and Globalization support
/**
*******************************************************************************
* Copyright (C) 2001-2011, International Business Machines Corporation and *
* others. All Rights Reserved. *
*******************************************************************************
*/
package com.ibm.icu.impl.data;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import com.ibm.icu.impl.ICUData;
import com.ibm.icu.impl.PatternProps;
/**
* A reader for text resource data in the current package or the package
* of a given class object. The
* resource data is loaded through the class loader, so it will
* typically be a file in the same directory as the *.class files, or
* a file within a JAR file in the corresponding subdirectory. The
* file must be a text file in one of the supported encodings; when the
* resource is opened by constructing a ResourceReader
* object the encoding is specified.
*
* @author Alan Liu
*/
public class ResourceReader {
private BufferedReader reader;
private String resourceName;
private String encoding; // null for default encoding
private Class root;
/**
* The one-based line number. Has the special value -1 before the
* object is initialized. Has the special value 0 after initialization
* but before the first line is read.
*/
private int lineNo;
/**
* Construct a reader object for the text file of the given name
* in this package, using the given encoding.
* @param resourceName the name of the text file located in this
* package's ".data" subpackage.
* @param encoding the encoding of the text file; if unsupported
* an exception is thrown
* @exception UnsupportedEncodingException if
* encoding is not supported by the JDK.
*/
public ResourceReader(String resourceName, String encoding)
throws UnsupportedEncodingException {
this(ICUData.class, "data/" + resourceName, encoding);
}
/**
* Construct a reader object for the text file of the given name
* in this package, using the default encoding.
* @param resourceName the name of the text file located in this
* package's ".data" subpackage.
*/
public ResourceReader(String resourceName) {
this(ICUData.class, "data/" + resourceName);
}
/**
* Construct a reader object for the text file of the given name
* in the given class's package, using the given encoding.
* @param resourceName the name of the text file located in the
* given class's package.
* @param encoding the encoding of the text file; if unsupported
* an exception is thrown
* @exception UnsupportedEncodingException if
* encoding is not supported by the JDK.
*/
public ResourceReader(Class rootClass, String resourceName, String encoding)
throws UnsupportedEncodingException {
this.root = rootClass;
this.resourceName = resourceName;
this.encoding = encoding;
lineNo = -1;
_reset();
}
/**
* Construct a reader object for the input stream associated with
* the given resource name.
* @param is the input stream of the resource
* @param resourceName the name of the resource
*/
public ResourceReader(InputStream is, String resourceName, String encoding) {
this.root = null;
this.resourceName = resourceName;
this.encoding = encoding;
this.lineNo = -1;
try {
InputStreamReader isr = (encoding == null)
? new InputStreamReader(is)
: new InputStreamReader(is, encoding);
this.reader = new BufferedReader(isr);
this.lineNo= 0;
}
catch (UnsupportedEncodingException e) {
}
}
/**
* Construct a reader object for the input stream associated with
* the given resource name.
* @param is the input stream of the resource
* @param resourceName the name of the resource
*/
public ResourceReader(InputStream is, String resourceName) {
this(is, resourceName, null);
}
/**
* Construct a reader object for the text file of the given name
* in the given class's package, using the default encoding.
* @param resourceName the name of the text file located in the
* given class's package.
*/
public ResourceReader(Class rootClass, String resourceName) {
this.root = rootClass;
this.resourceName = resourceName;
this.encoding = null;
lineNo = -1;
try {
_reset();
} catch (UnsupportedEncodingException e) {}
}
/**
* Read and return the next line of the file or null
* if the end of the file has been reached.
*/
public String readLine() throws IOException {
if (lineNo == 0) {
// Remove BOMs
++lineNo;
String line = reader.readLine();
if (line.charAt(0) == '\uFFEF' ||
line.charAt(0) == '\uFEFF') {
line = line.substring(1);
}
return line;
}
++lineNo;
return reader.readLine();
}
/**
* Read a line, ignoring blank lines and lines that start with
* '#'.
* @param trim if true then trim leading Pattern_White_Space.
*/
public String readLineSkippingComments(boolean trim) throws IOException {
for (;;) {
String line = readLine();
if (line == null) {
return line;
}
// Skip over white space
int pos = PatternProps.skipWhiteSpace(line, 0);
// Ignore blank lines and comment lines
if (pos == line.length() || line.charAt(pos) == '#') {
continue;
}
// Process line
if (trim) line = line.substring(pos);
return line;
}
}
/**
* Read a line, ignoring blank lines and lines that start with
* '#'. Do not trim leading Pattern_White_Space.
*/
public String readLineSkippingComments() throws IOException {
return readLineSkippingComments(false);
}
/**
* Return the one-based line number of the last line returned by
* readLine() or readLineSkippingComments(). Should only be called
* after a call to one of these methods; otherwise the return
* value is undefined.
*/
public int getLineNumber() {
return lineNo;
}
/**
* Return a string description of the position of the last line
* returned by readLine() or readLineSkippingComments().
*/
public String describePosition() {
return resourceName + ':' + lineNo;
}
/**
* Reset this reader so that the next call to
* readLine() returns the first line of the file
* again. This is a somewhat expensive call, however, calling
* reset() after calling it the first time does
* nothing if readLine() has not been called in
* between.
*/
public void reset() {
try {
_reset();
} catch (UnsupportedEncodingException e) {}
// We swallow this exception, if there is one. If the encoding is
// invalid, the constructor will have thrown this exception already and
// the caller shouldn't use the object afterwards.
}
/**
* Reset to the start by reconstructing the stream and readers.
* We could also use mark() and reset() on the stream or reader,
* but that would cause them to keep the stream data around in
* memory. We don't want that because some of the resource files
* are large, e.g., 400k.
*/
private void _reset() throws UnsupportedEncodingException {
if (lineNo == 0) {
return;
}
InputStream is = ICUData.getStream(root, resourceName);
if (is == null) {
throw new IllegalArgumentException("Can't open " + resourceName);
}
InputStreamReader isr =
(encoding == null) ? new InputStreamReader(is) :
new InputStreamReader(is, encoding);
reader = new BufferedReader(isr);
lineNo = 0;
}
}