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Java example source code file (QueryStringEncoder.java)

This example Java source code file (QueryStringEncoder.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arraylist, charset, net, network, nullpointerexception, override, param, querystringencoder, string, stringbuilder, unsupportedencodingexception, uri, urisyntaxexception, util

The QueryStringEncoder.java Java example source code

/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project licenses this file to you 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 io.netty.handler.codec.http;

import java.io.UnsupportedEncodingException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URLEncoder;
import java.nio.charset.Charset;
import java.nio.charset.UnsupportedCharsetException;
import java.util.ArrayList;
import java.util.List;

/**
 * Creates an URL-encoded URI from a path string and key-value parameter pairs.
 * This encoder is for one time use only.  Create a new instance for each URI.
 *
 * <pre>
 * {@link QueryStringEncoder} encoder = new {@link QueryStringEncoder}("/hello");
 * encoder.addParam("recipient", "world");
 * assert encoder.toString().equals("/hello?recipient=world");
 * </pre>
 * @see QueryStringDecoder
 */
public class QueryStringEncoder {

    private final Charset charset;
    private final String uri;
    private final List<Param> params = new ArrayList();

    /**
     * Creates a new encoder that encodes a URI that starts with the specified
     * path string.  The encoder will encode the URI in UTF-8.
     */
    public QueryStringEncoder(String uri) {
        this(uri, HttpConstants.DEFAULT_CHARSET);
    }

    /**
     * Creates a new encoder that encodes a URI that starts with the specified
     * path string in the specified charset.
     */
    public QueryStringEncoder(String uri, Charset charset) {
        if (uri == null) {
            throw new NullPointerException("getUri");
        }
        if (charset == null) {
            throw new NullPointerException("charset");
        }

        this.uri = uri;
        this.charset = charset;
    }

    /**
     * Adds a parameter with the specified name and value to this encoder.
     */
    public void addParam(String name, String value) {
        if (name == null) {
            throw new NullPointerException("name");
        }
        params.add(new Param(name, value));
    }

    /**
     * Returns the URL-encoded URI object which was created from the path string
     * specified in the constructor and the parameters added by
     * {@link #addParam(String, String)} getMethod.
     */
    public URI toUri() throws URISyntaxException {
        return new URI(toString());
    }

    /**
     * Returns the URL-encoded URI which was created from the path string
     * specified in the constructor and the parameters added by
     * {@link #addParam(String, String)} getMethod.
     */
    @Override
    public String toString() {
        if (params.isEmpty()) {
            return uri;
        } else {
            StringBuilder sb = new StringBuilder(uri).append('?');
            for (int i = 0; i < params.size(); i++) {
                Param param = params.get(i);
                sb.append(encodeComponent(param.name, charset));
                if (param.value != null) {
                    sb.append('=');
                    sb.append(encodeComponent(param.value, charset));
                }
                if (i != params.size() - 1) {
                    sb.append('&');
                }
            }
            return sb.toString();
        }
    }

    private static String encodeComponent(String s, Charset charset) {
        // TODO: Optimize me.
        try {
            return URLEncoder.encode(s, charset.name()).replace("+", "%20");
        } catch (UnsupportedEncodingException ignored) {
            throw new UnsupportedCharsetException(charset.name());
        }
    }

    private static final class Param {

        final String name;
        final String value;

        Param(String name, String value) {
            this.value = value;
            this.name = name;
        }
    }
}

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