cherry.foundation.download.Rfc5987Encoder.java Source code

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Here is the source code for cherry.foundation.download.Rfc5987Encoder.java

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/*
 * Copyright 2015 agwlvssainokuni
 *
 * 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 cherry.foundation.download;

import java.nio.charset.Charset;

import org.apache.commons.lang3.StringUtils;

import com.google.common.base.Function;

public class Rfc5987Encoder implements Function<String, String> {

    private Charset charset;

    private String languageTag;

    public void setCharset(Charset charset) {
        this.charset = charset;
    }

    public void setLanguageTag(String languageTag) {
        this.languageTag = languageTag;
    }

    @Override
    public String apply(String input) {

        byte[] b = input.getBytes(charset);
        StringBuilder builder = new StringBuilder(b.length * 3);

        builder.append(charset.name()).append("'");
        if (StringUtils.isNotBlank(languageTag)) {
            builder.append(languageTag);
        }
        builder.append("'");

        for (int i = 0; i < b.length; i++) {
            if (isAttrChar((char) b[i])) {
                builder.append((char) b[i]);
            } else {
                builder.append('%');
                int c = 0xff & b[i];
                if (c < 0x10) {
                    builder.append('0');
                }
                builder.append(Integer.toHexString(c));
            }
        }
        return builder.toString();
    }

    private boolean isAttrChar(char c) {
        // DIGIT
        if (c >= '0' && c <= '9') {
            return true;
        }
        // ALPHA
        if (c >= 'A' && c <= 'Z') {
            return true;
        }
        if (c >= 'a' && c <= 'z') {
            return true;
        }
        // token except ( "*" / "'" / "%" )
        switch (c) {
        case '!':
        case '#':
        case '$':
        case '&':
        case '+':
        case '-':
        case '.':
        case '^':
        case '_':
        case '`':
        case '|':
        case '~':
            return true;
        default:
            return false;
        }
    }

}