ResourceReader.java
// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
*******************************************************************************
* Copyright (C) 2001-2015, International Business Machines Corporation and
* others. All Rights Reserved.
*******************************************************************************
*/
package com.ibm.icu.impl.data;
import com.ibm.icu.impl.ICUData;
import com.ibm.icu.impl.PatternProps;
import java.io.BufferedReader;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
/**
* 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 <code>ResourceReader</code> object the encoding is specified.
*
* <p>2015-sep-03 TODO: Only used in com.ibm.icu.dev.test.format, move there.
*
* @author Alan Liu
*/
public class ResourceReader implements Closeable {
private BufferedReader reader = null;
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 <code>encoding</code> 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 <code>encoding</code> 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 <code>null</code> 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 != null && (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 <code>readLine()</code> returns the first line of
* the file again. This is a somewhat expensive call, however, calling <code>reset()</code>
* after calling it the first time does nothing if <code>readLine()</code> 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 {
try {
close();
} catch (IOException e) {
}
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;
}
/**
* Closes the underlying reader and releases any system resources associated with it. If the
* stream is already closed then invoking this method has no effect.
*/
@Override
public void close() throws IOException {
if (reader != null) {
reader.close();
reader = null;
}
}
}