/*
* Copyright (C) 2009 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 android.util;
import android.os.Build;
import android.text.TextUtils;
import java.nio.charset.Charset;
import java.nio.charset.IllegalCharsetNameException;
import java.nio.charset.UnsupportedCharsetException;
import java.util.HashMap;
import java.util.Map;
/**
* <p>
* A class containing utility methods related to character sets. This
* class is primarily useful for code that wishes to be vendor-aware
* in its interpretation of Japanese charset names (used in DoCoMo,
* KDDI, and SoftBank).
* </p>
*
* <p>
* <b>Note:</b> Developers will need to add an appropriate mapping for
* each vendor-specific charset. You may need to modify the C libraries
* like icu4c in order to let Android support an additional charset.
* </p>
*
* @hide
*/
public final class CharsetUtils {
/**
* name of the vendor "DoCoMo". <b>Note:</b> This isn't a public
* constant, in order to keep this class from becoming a de facto
* reference list of vendor names.
*/
private static final String VENDOR_DOCOMO = "docomo";
/**
* Name of the vendor "KDDI".
*/
private static final String VENDOR_KDDI = "kddi";
/**
* Name of the vendor "SoftBank".
*/
private static final String VENDOR_SOFTBANK = "softbank";
/**
* Represents one-to-one mapping from a vendor name to a charset specific to the vendor.
*/
private static final Map<String, String> sVendorShiftJisMap = new HashMap<String, String>();
static {
// These variants of Shift_JIS come from icu's mapping data (convrtrs.txt)
sVendorShiftJisMap.put(VENDOR_DOCOMO, "docomo-shift_jis-2007");
sVendorShiftJisMap.put(VENDOR_KDDI, "kddi-shift_jis-2007");
sVendorShiftJisMap.put(VENDOR_SOFTBANK, "softbank-shift_jis-2007");
}
/**
* This class is uninstantiable.
*/
private CharsetUtils() {
// This space intentionally left blank.
}
/**
* Returns the name of the vendor-specific character set
* corresponding to the given original character set name and
* vendor. If there is no vendor-specific character set for the
* given name/vendor pair, this returns the original character set name.
*
* @param charsetName the base character set name
* @param vendor the vendor to specialize for. All characters should be lower-cased.
* @return the specialized character set name, or {@code charsetName} if
* there is no specialized name
*/
public static String nameForVendor(String charsetName, String vendor) {
if (!TextUtils.isEmpty(charsetName) && !TextUtils.isEmpty(vendor)) {
// You can add your own mapping here.
if (isShiftJis(charsetName)) {
final String vendorShiftJis = sVendorShiftJisMap.get(vendor);
if (vendorShiftJis != null) {
return vendorShiftJis;
}
}
}
return charsetName;
}
/**
* Returns the name of the vendor-specific character set
* corresponding to the given original character set name and the
* default vendor (that is, the targeted vendor of the device this
* code is running on). This method merely calls through to
* {@link #nameForVendor(String,String)}, passing the default vendor
* as the second argument.
*
* @param charsetName the base character set name
* @return the specialized character set name, or {@code charsetName} if
* there is no specialized name
*/
public static String nameForDefaultVendor(String charsetName) {
return nameForVendor(charsetName, getDefaultVendor());
}
/**
* Returns the vendor-specific character set corresponding to the
* given original character set name and vendor. If there is no
* vendor-specific character set for the given name/vendor pair,
* this returns the character set corresponding to the original
* name. The vendor name is matched case-insensitively. This
* method merely calls {@code Charset.forName()} on a name
* transformed by a call to {@link #nameForVendor(String,String)}.
*
* @param charsetName the base character set name
* @param vendor the vendor to specialize for
* @return the specialized character set, or the one corresponding
* directly to {@code charsetName} if there is no specialized
* variant
* @throws UnsupportedCharsetException thrown if the named character
* set is not supported by the system
* @throws IllegalCharsetNameException thrown if {@code charsetName}
* has invalid syntax
*/
public static Charset charsetForVendor(String charsetName, String vendor)
throws UnsupportedCharsetException, IllegalCharsetNameException {
charsetName = nameForVendor(charsetName, vendor);
return Charset.forName(charsetName);
}
/**
* Returns the vendor-specific character set corresponding to the
* given original character set name and default vendor (that is,
* the targeted vendor of the device this code is running on).
* This method merely calls through to {@link
* #charsetForVendor(String,String)}, passing the default vendor
* as the second argument.
*
* @param charsetName the base character set name
* @return the specialized character set, or the one corresponding
* directly to {@code charsetName} if there is no specialized
* variant
* @throws UnsupportedCharsetException thrown if the named character
* set is not supported by the system
* @throws IllegalCharsetNameException thrown if {@code charsetName}
* has invalid syntax
*/
public static Charset charsetForVendor(String charsetName)
throws UnsupportedCharsetException, IllegalCharsetNameException {
return charsetForVendor(charsetName, getDefaultVendor());
}
/**
* Returns whether the given character set name indicates the Shift-JIS
* encoding. Returns false if the name is null.
*
* @param charsetName the character set name
* @return {@code true} if the name corresponds to Shift-JIS or
* {@code false} if not
*/
private static boolean isShiftJis(String charsetName) {
// Bail quickly if the length doesn't match.
if (charsetName == null) {
return false;
}
int length = charsetName.length();
if (length != 4 && length != 9) {
return false;
}
return charsetName.equalsIgnoreCase("shift_jis")
|| charsetName.equalsIgnoreCase("shift-jis")
|| charsetName.equalsIgnoreCase("sjis");
}
/**
* Gets the default vendor for this build.
*
* @return the default vendor name
*/
private static String getDefaultVendor() {
return Build.BRAND;
}
}