Java Utililty Methods URL Download

List of utility methods to do URL Download

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Description

The list of methods to do URL Download are organized into topic(s).

Method

StringdownloadAsString(String url)
download As String 
try (InputStream is = new URL(url).openStream();
        InputStreamReader isr = new InputStreamReader(is);
        BufferedReader br = new BufferedReader(isr)) {
    StringBuilder sb = new StringBuilder();
    String line;
    while ((line = br.readLine()) != null) {
        sb.append(line).append('\n');
    return sb.toString();
voiddownloadBinary(URL BaseURL, String Name, File TargetDirectory)
download Binary 
URL TheURL = new URL(BaseURL, Name);
File TestFile = new File(TargetDirectory, Name);
downloadBinary(TheURL, TestFile);
byte[]downloadData(String url, String params)
download Data 
HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection();
connection.setRequestMethod("POST");
connection.setDoOutput(true);
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
OutputStream output = connection.getOutputStream();
output.write(params.getBytes());
output.close();
int code = connection.getResponseCode();
...
voiddownloadDirectory(URL dirUrl, File destDir)
Downloads url directory to target directory (url directory will be subdirectory of target directory); example: dowloadDirectory(new URL("http://dir0/dir1/dir2"), new File("/home/junk")) behaves like cp -r dir2 /home/junk/dir2 such that the directory /home/junk/dir2 exists with all its sub dirs and files. 
if (!destDir.exists())
    throw new IOException(destDir + " does not exist.");
if (!destDir.isDirectory())
    throw new IOException(destDir + " is not a directory.");
Vector<String> dirListing = getFileContents(dirUrl);
String urlDirName = (new File(dirUrl.getFile()).getName());
File destDir2 = new File(destDir, urlDirName);
for (String line : dirListing) {
...
FiledownloadFile(File parent, String prefix, String suffix, URL url)
Download file. 
File file = File.createTempFile(prefix, suffix, parent);
URLConnection conn = null;
final String protocol = url.getProtocol().toLowerCase();
try {
    conn = url.openConnection();
    if ("http".equals(protocol) || "https".equals(protocol)) {
        HttpURLConnection http = (HttpURLConnection) conn;
        http.setInstanceFollowRedirects(false);
...
booleandownloadFile(File target, String urlStr)
download File 
InputStream in = openStream(urlStr);
if (in != null) {
    System.out.println("downloading " + urlStr + "...");
    writeStreamToFile(target, in);
    System.out.println("   ...done");
} else {
    System.out.println("no file found at " + urlStr);
return in != null;
byte[]downloadFile(final String url)
download File 
final URL fileUrl = new URL(url);
final InputStream in = fileUrl.openStream();
final ByteArrayOutputStream buf = new ByteArrayOutputStream();
final byte[] readBuf = new byte[1024];
int read = in.read(readBuf);
while (read > 0) {
    buf.write(readBuf, 0, read);
    read = in.read(readBuf);
...
voiddownloadFile(String fileURL, String localFileName, String destinationDir)
download File 
OutputStream outStream = null;
InputStream is = null;
try {
    URL Url = new URL(fileURL);
    outStream = new BufferedOutputStream(new FileOutputStream(destinationDir + '/' + localFileName));
    URLConnection uCon = Url.openConnection();
    is = uCon.getInputStream();
    int byteRead = 0;
...
voiddownloadFile(String fileURL, String saveDir)
Downloads a file from a URL 
URL url = new URL(fileURL);
HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
int responseCode = httpConn.getResponseCode();
if (responseCode == HttpURLConnection.HTTP_OK) {
    String fileName = "";
    String disposition = httpConn.getHeaderField("Content-Disposition");
    String contentType = httpConn.getContentType();
    int contentLength = httpConn.getContentLength();
...
StringdownloadFile(String fileURL, String savePath)
Downloads a file from a URL 
System.err.printf("Downloading %s to %s\n", fileURL, savePath);
URL url = new URL(fileURL);
HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
int responseCode = httpConn.getResponseCode();
if (responseCode == HttpURLConnection.HTTP_OK) {
    String fileName = "";
    String disposition = httpConn.getHeaderField("Content-Disposition");
    String contentType = httpConn.getContentType();
...