Java URL Download get(String url, Map headers)

Description

Send a get request

License

Open Source License

Parameter

Parameter	Description
url	Url as string
headers	Optional map with headers

Exception

Parameter	Description
IOException	an exception

Return

response Response as string

Declaration

static public String get(String url, Map<String, String> headers) 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.util.Map;

public class Main {
    /**//from   w  ww . j a va 2s . c  o m
     * 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);
    }

    /**
     * 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;
    }

    /**
     * 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();
    }
}

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