am e713f57a: am d82b1c3b: am 9d8721f8: Merge "Remove dead code."

/*

 * 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;

    }

}