Http Header Helper : HttpURLConnection « Network « Java Tutorial

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import java.nio.charset.Charset;
import java.nio.charset.IllegalCharsetNameException;
import java.nio.charset.UnsupportedCharsetException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

public final class HttpHeaderHelper {
    public static final String ACCEPT_ENCODING = "Accept-Encoding";
    public static final String CONTENT_TYPE = "Content-Type";
    public static final String CONTENT_ID = "Content-ID";
    public static final String CONTENT_ENCODING = "Content-Encoding";
    public static final String CONTENT_TRANSFER_ENCODING = "Content-Transfer-Encoding";
    public static final String COOKIE = "Cookie";
    public static final String TRANSFER_ENCODING = "Transfer-Encoding";
    public static final String CHUNKED = "chunked";
    public static final String CONNECTION = "Connection";
    public static final String CLOSE = "close";
    public static final String AUTHORIZATION = "Authorization";
    private static final Charset UTF8 = Charset.forName("utf-8"); 

    private static Map<String, String> internalHeaders = new HashMap<String, String>();
    private static Map<String, String> encodings = new ConcurrentHashMap<String, String>();
    static {
        internalHeaders.put("Accept-Encoding", "accept-encoding");
        internalHeaders.put("Content-Encoding", "content-encoding");
        internalHeaders.put("Content-Type", "content-type");
        internalHeaders.put("Content-ID", "content-id");
        internalHeaders.put("Content-Transfer-Encoding", "content-transfer-encoding"); 
        internalHeaders.put("Transfer-Encoding", "transfer-encoding");
        internalHeaders.put("Connection", "connection");
        internalHeaders.put("authorization", "Authorization");
        internalHeaders.put("soapaction", "SOAPAction");
        internalHeaders.put("accept", "Accept");
    private HttpHeaderHelper() {
    public static List getHeader(Map<String, List<String>> headerMap, String key) {
        return headerMap.get(getHeaderKey(key));
    public static String getHeaderKey(String key) {
        if (internalHeaders.containsKey(key)) {
            return internalHeaders.get(key);
        } else {
            return key;
    //helper to map the charsets that various things send in the http Content-Type header 
    //into something that is actually supported by Java and the Stax parsers and such.
    public static String mapCharset(String enc) {
        if (enc == null) {
        //older versions of tomcat don't properly parse ContentType headers with stuff
        //after charset="UTF-8"
        int idx = enc.indexOf(";");
        if (idx != -1) {
            enc = enc.substring(0, idx);
        // Charsets can be quoted. But it's quite certain that they can't have escaped quoted or
        // anything like that.
        enc = enc.replace("\"", "").trim();
        enc = enc.replace("'", "");
        if ("".equals(enc)) {
        String newenc = encodings.get(enc);
        if (newenc == null) {
            try {
                newenc = Charset.forName(enc).name();
            } catch (IllegalCharsetNameException icne) {
                return null;
            } catch (UnsupportedCharsetException uce) {
                return null;
            encodings.put(enc, newenc);
        return newenc;

19.6.1.Get the date of a url connection
19.6.2.Get the document expiration date
19.6.3.Get the document Last-modified date
19.6.4.Show the content type
19.6.5.Show the content length
19.6.6.Display request method
19.6.7.Get response code
19.6.8.Display response message
19.6.9.Display header information
19.6.10.Download and display the content
19.6.11.A Web Page Source Viewer
19.6.12.Reading from a URLConnection
19.6.13.Use BufferedReader to read content from a URL
19.6.14.Check if a page exists
19.6.15.Identify ourself to a proxy
19.6.16.Connect through a Proxy can be used to send the credentials when needed
19.6.18.Read data from a URL
19.6.19.Dump a page using the HTTPS protocol
19.6.20.Save URL contents to a file
19.6.21.Http connection Utilities
19.6.22.Parsing and formatting HTTP dates as used in cookies and other headers.
19.6.23.Last Modified
19.6.24.URL connection and proxy
19.6.25.Http Constants
19.6.26.Http Header Helper
19.6.27.A utility class for parsing HTTP dates as used in cookies and other headers