Java URL Query getQueryParams(String url)

Description

Retrieve the query parameters from given url

License

Open Source License

Parameter

Parameter	Description
url	Url containing query parameters

Exception

Parameter	Description
IOException	an exception

Return

params Map with query parameters

Declaration

static public Map<String, String> getQueryParams(String url) throws IOException 

Method Source Code

//package com.java2s;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLDecoder;

import java.util.HashMap;
import java.util.Map;

public class Main {
    /**/*from  ww  w . jav  a2s.c o m*/
     * Retrieve the query parameters from given url
     *
     * @param url Url containing query parameters
     * @return params     Map with query parameters
     * @throws IOException
     */
    static public Map<String, String> getQueryParams(String url) throws IOException {
        Map<String, String> params = new HashMap<String, String>();

        int start = url.indexOf('?');
        while (start != -1) {
            // read parameter name
            int equals = url.indexOf('=', start);
            String param = "";
            if (equals != -1) {
                param = url.substring(start + 1, equals);
            } else {
                param = url.substring(start + 1);
            }

            // read parameter value
            String value = "";
            if (equals != -1) {
                start = url.indexOf('&', equals);
                if (start != -1) {
                    value = url.substring(equals + 1, start);
                } else {
                    value = url.substring(equals + 1);
                }
            }

            params.put(URLDecoder.decode(param, "UTF-8"), URLDecoder.decode(value, "UTF-8"));
        }

        return params;
    }

    /**
     * Send a put request
     *
     * @param url     Url as string
     * @param body    Request body as string
     * @param headers Optional map with headers
     * @return response   Response as string
     * @throws IOException
     */
    static public String put(String url, String body, Map<String, String> headers) throws IOException {
        return fetch("PUT", url, body, headers);
    }

    /**
     * Send a put request
     *
     * @param url Url as string
     * @return response   Response as string
     * @throws IOException
     */
    static public String put(String url, String body) throws IOException {
        return put(url, body, null);
    }

    /**
     * Send a request
     *
     * @param method  HTTP method, for example "GET" or "POST"
     * @param url     Url as string
     * @param body    Request body as string
     * @param headers Optional map with headers
     * @return response   Response as string
     * @throws IOException
     */
    static public String fetch(String method, String url, String body, Map<String, String> headers)
            throws IOException {
        // connection
        URL u = new URL(url);
        HttpURLConnection conn = (HttpURLConnection) u.openConnection();
        conn.setConnectTimeout(10000);
        conn.setReadTimeout(10000);

        // method
        if (method != null) {
            conn.setRequestMethod(method);
        }

        // headers
        if (headers != null) {
            for (String key : headers.keySet()) {
                conn.addRequestProperty(key, headers.get(key));
            }
        }

        // body
        if (body != null) {
            conn.setDoOutput(true);
            OutputStream os = conn.getOutputStream();
            os.write(body.getBytes());
            os.flush();
            os.close();
        }

        // response
        InputStream is = conn.getInputStream();
        String response = streamToString(is);
        is.close();

        // handle redirects
        if (conn.getResponseCode() == 301) {
            String location = conn.getHeaderField("Location");
            return fetch(method, location, body, headers);
        }

        return response;
    }

    /**
     * Send a get request
     *
     * @param url
     * @return response
     * @throws IOException
     */
    static public String get(String url) throws IOException {
        return get(url, null);
    }

    /**
     * Send a get request
     *
     * @param url     Url as string
     * @param headers Optional map with headers
     * @return response   Response as string
     * @throws IOException
     */
    static public String get(String url, Map<String, String> headers) throws IOException {
        return fetch("GET", url, null, headers);
    }

    /**
     * Read an input stream into a string
     *
     * @param in
     * @return
     * @throws IOException
     */
    static public String streamToString(InputStream in) throws IOException {
        StringBuffer out = new StringBuffer();
        byte[] b = new byte[4096];
        for (int n; (n = in.read(b)) != -1;) {
            out.append(new String(b, 0, n));
        }
        return out.toString();
    }
}

Related

1. query(URL host, String endpoint, String customer, String name, OutputStream out)
2. queryEndpoint(String url)
3. appendQueryParams(String url, Map params)
4. getHTTPQuery(String urlToRead)
5. queryHtml(String url)
6. search(String query, int numberOfUrls)