LatinIME/java/src/com/android/inputmethod/dictionarypack/AssetFileAddress.java

67 lines
2.4 KiB
Java

/*
* Copyright (C) 2011 The Android Open Source Project
*
* 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
*
* 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.android.inputmethod.dictionarypack;
import java.io.File;
/**
* Immutable class to hold the address of an asset.
* As opposed to a normal file, an asset is usually represented as a contiguous byte array in
* the package file. Open it correctly thus requires the name of the package it is in, but
* also the offset in the file and the length of this data. This class encapsulates these three.
*/
final class AssetFileAddress {
public final String mFilename;
public final long mOffset;
public final long mLength;
public AssetFileAddress(final String filename, final long offset, final long length) {
mFilename = filename;
mOffset = offset;
mLength = length;
}
/**
* Makes an AssetFileAddress. This may return null.
*
* @param filename the filename.
* @return the address, or null if the file does not exist or the parameters are not valid.
*/
public static AssetFileAddress makeFromFileName(final String filename) {
if (null == filename) return null;
final File f = new File(filename);
if (!f.isFile()) return null;
return new AssetFileAddress(filename, 0l, f.length());
}
/**
* Makes an AssetFileAddress. This may return null.
*
* @param filename the filename.
* @param offset the offset.
* @param length the length.
* @return the address, or null if the file does not exist or the parameters are not valid.
*/
public static AssetFileAddress makeFromFileNameAndOffset(final String filename,
final long offset, final long length) {
if (null == filename) return null;
final File f = new File(filename);
if (!f.isFile()) return null;
return new AssetFileAddress(filename, offset, length);
}
}