AI 147994: First cut of CharsetUtils, a utility class that aims to (b4c218ea) · Commits · e / os / android_frameworks_base

core/java/android/util/CharsetUtils.java

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		/*
		* 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 java.nio.charset.Charset;
		import java.nio.charset.IllegalCharsetNameException;
		import java.nio.charset.UnsupportedCharsetException;

		/**
		* 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 encoding names.
		*
		* <p>As of this writing, the only vendor that is recognized by this
		* class is Docomo (identified case-insensitively as {@code "docomo"}).</p>
		*
		* <b>Note:</b> This class is hidden in Cupcake, with a plan to
		* un-hide in Donut. This was done because the first deployment to use
		* this code is based on Cupcake, but the API had to be introduced
		* after the public API freeze for that release. The upshot is that
		* only system applications can safely use this class until Donut is
		* available.
		*
		* @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";

		/**
		* 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. The vendor name is matched case-insensitively.
		*
		* @param charsetName the base character set name
		* @param vendor the vendor to specialize for
		* @return the specialized character set name, or {@code charsetName} if
		* there is no specialized name
		*/
		public static String nameForVendor(String charsetName, String vendor) {
		// TODO: Eventually, this may want to be table-driven.

		if (vendor.equalsIgnoreCase(VENDOR_DOCOMO)
		&& isShiftJis(charsetName)) {
		return "docomo-shift_jis-2007";
		}

		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.
		*
		* @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) {
		if (charsetName.length() != 9) {
		// Bail quickly if the length doesn't match.
		return false;
		}

		return charsetName.equalsIgnoreCase("shift_jis")
		\|\| charsetName.equalsIgnoreCase("shift-jis");
		}

		/**
		* Gets the default vendor for this build.
		*
		* @return the default vendor name
		*/
		private static String getDefaultVendor() {
		return Build.BRAND;
		}
		}