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Common utilities I find useful in many of my projects.
package org.dstadler.commons.net;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.nio.charset.StandardCharsets;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLSocketFactory;
import org.apache.commons.io.IOUtils;
import org.dstadler.commons.logging.jdk.LoggerFactory;
/**
* Collection of simple utility-methods for accessing network resources.
*
* For more sophisticated access use {@link org.dstadler.commons.http.HttpClientWrapper}.
*/
public class UrlUtils {
private static final Logger LOGGER = LoggerFactory.make();
/*
* The first n bytes of data to print to FINE in retrieveRawData()
*/
private static final int REPORT_PEEK_COUNT = 200;
/**
* Download data from an URL.
*
* @param sUrl The full URL used to download the content.
* @param timeout The timeout in milliseconds that is used for both
* connection timeout and read timeout.
*
* @return The resulting data, e.g. a HTML string.
*
* @throws IOException If accessing the resource fails.
*/
public static String retrieveData(String sUrl, int timeout) throws IOException {
return retrieveData(sUrl, null, timeout);
}
/**
* Download data from an URL, if necessary converting from a character encoding.
*
* @param sUrl The full URL used to download the content.
* @param encoding An encoding, e.g. UTF-8, ISO-8859-15. Can be null.
* @param timeout The timeout in milliseconds that is used for both
* connection timeout and read timeout.
*
* @return The resulting data, e.g. a HTML string.
*
* @throws IOException If accessing the resource fails.
*/
public static String retrieveData(String sUrl, String encoding, int timeout) throws IOException {
return retrieveData(sUrl, encoding, timeout, null);
}
/**
* Download data from an URL, if necessary converting from a character encoding.
*
* @param sUrl The full URL used to download the content.
* @param encoding An encoding, e.g. UTF-8, ISO-8859-15. Can be null.
* @param timeout The timeout in milliseconds that is used for both
* connection timeout and read timeout.
* @param sslFactory The SSLFactory to use for the connection, this allows to support custom SSL certificates
*
* @return The resulting data, e.g. a HTML string.
*
* @throws IOException If accessing the resource fails.
*/
public static String retrieveData(String sUrl, String encoding, int timeout, SSLSocketFactory sslFactory) throws IOException {
byte[] rawData = retrieveRawData(sUrl, timeout, sslFactory);
if(encoding == null) {
return new String(rawData); // NOSONAR
}
return new String(rawData, encoding);
}
/**
* Download data from an URL and return the raw bytes.
*
* @param sUrl The full URL used to download the content.
* @param timeout The timeout in milliseconds that is used for both
* connection timeout and read timeout.
*
* @return The resulting data, e.g. a HTML string as byte array.
*
* @throws IOException If accessing the resource fails.
*/
public static byte[] retrieveRawData(String sUrl, int timeout) throws IOException {
return retrieveRawData(sUrl, timeout, null);
}
/**
* Download data from an URL and return the raw bytes.
*
* @param sUrl The full URL used to download the content.
* @param timeout The timeout in milliseconds that is used for both
* connection timeout and read timeout.
* @param sslFactory The SSLFactory to use for the connection, this allows to support custom SSL certificates
*
* @return The resulting data, e.g. a HTML string as byte array.
*
* @throws IOException If accessing the resource fails.
*/
public static byte[] retrieveRawData(String sUrl, int timeout, SSLSocketFactory sslFactory) throws IOException {
URL url = new URL(sUrl);
LOGGER.fine("Using the following URL for retrieving the data: " + url);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
// set specified timeout if non-zero
if(timeout != 0) {
conn.setConnectTimeout(timeout);
conn.setReadTimeout(timeout);
}
try {
conn.setDoOutput(false);
conn.setDoInput(true);
if(conn instanceof HttpsURLConnection && sslFactory != null) {
((HttpsURLConnection)conn).setSSLSocketFactory(sslFactory);
}
conn.connect();
int code = conn.getResponseCode();
if (code != HttpURLConnection.HTTP_OK &&
code != HttpURLConnection.HTTP_CREATED &&
code != HttpURLConnection.HTTP_ACCEPTED) {
String msg = "Error " + code + " returned while retrieving response for url '" + url
+ "' message from client: " + conn.getResponseMessage();
LOGGER.warning(msg);
throw new IOException(msg);
}
try (InputStream strm = conn.getInputStream()) {
return IOUtils.toByteArray(strm);
}
// actually read the contents, even if we are not using it to simulate a full download of the data
/*ByteArrayOutputStream memStream = new ByteArrayOutputStream(conn.getContentLength() == -1 ? 40000 : conn.getContentLength());
try {
byte b[] = new byte[4096];
int len;
while ((len = strm.read(b)) > 0) {
memStream.write(b, 0, len);
}
} finally {
memStream.close();
}
if(LOGGER.isLoggable(Level.FINE)) {
LOGGER.fine("Received data, size: " + memStream.size() + "(" + conn.getContentLength() + ") first bytes: "
+ replaceInvalidChar(memStream.toString().substring(0, Math.min(memStream.size(), REPORT_PEEK_COUNT))));
}
return memStream.toByteArray();*/
} finally {
conn.disconnect();
}
}
/**
* Download data from an URL with a POST request, if necessary converting from a character encoding.
*
* @param sUrl The full URL used to download the content.
* @param encoding An encoding, e.g. UTF-8, ISO-8859-15. Can be null.
* @param postRequestBody the body of the POST request, e.g. request parameters; must not be null
* @param contentType the content-type of the POST request; may be null
* @param timeout The timeout in milliseconds that is used for both connection timeout and read timeout.
* @return The response from the HTTP POST call.
* @throws IOException If accessing the resource fails.
*/
public static String retrieveDataPost(String sUrl, String encoding, String postRequestBody, String contentType, int timeout) throws IOException {
return retrieveStringInternalPost(sUrl, encoding, postRequestBody, contentType, timeout, null);
}
/**
* Download data from an URL with a POST request, if necessary converting from a character encoding.
*
* @param sUrl The full URL used to download the content.
* @param encoding An encoding, e.g. UTF-8, ISO-8859-15. Can be null.
* @param postRequestBody the body of the POST request, e.g. request parameters; must not be null
* @param contentType the content-type of the POST request; may be null
* @param timeout The timeout in milliseconds that is used for both connection timeout and read timeout.
* @param sslFactory The SSLFactory to use for the connection, this allows to support custom SSL certificates
* @return The response from the HTTP POST call.
* @throws IOException If accessing the resource fails.
*/
public static String retrieveDataPost(String sUrl, String encoding, String postRequestBody, String contentType, int timeout, SSLSocketFactory sslFactory) throws IOException {
return retrieveStringInternalPost(sUrl, encoding, postRequestBody, contentType, timeout, sslFactory);
}
private static String retrieveStringInternalPost(String sUrl, String encoding, String postRequestBody, String contentType, int timeout, SSLSocketFactory sslFactory) throws IOException {
byte[] rawData = retrieveRawInternalPost(sUrl, postRequestBody, contentType, timeout, sslFactory);
return encoding != null ? new String(rawData, encoding) : new String(rawData); // NOSONAR
}
private static byte[] retrieveRawInternalPost(String sUrl, String postRequestBody, String contentType, int timeout, SSLSocketFactory sslFactory) throws IOException {
if (postRequestBody == null) {
throw new IllegalArgumentException("POST request body must not be null");
}
URL url = new URL(sUrl);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
try {
prepareConnection(connection, timeout, sslFactory);
writePostRequest(connection, postRequestBody, contentType);
connection.connect();
int responseCode = connection.getResponseCode();
if (!responseCodeValid(responseCode)) {
String message = "Error " + responseCode + " returned while retrieving response for url " + url + ", response message: " + connection.getResponseMessage();
LOGGER.warning(message);
throw new IOException(message);
}
// actually read the contents, even if we are not using it to simulate a full download of the data
try (ByteArrayOutputStream memStream = new ByteArrayOutputStream(connection.getContentLength() == -1 ?
40000 : connection.getContentLength())) {
try (InputStream in = connection.getInputStream()) {
IOUtils.copy(in, memStream);
}
if (LOGGER.isLoggable(Level.FINE)) {
LOGGER.log(Level.FINE, "Received data, size: " + memStream.size() +
" (" + connection.getContentLength() + ") first bytes: " +
replaceInvalidChars(new String(memStream.toByteArray(), 0,
Math.min(memStream.size(), REPORT_PEEK_COUNT), StandardCharsets.US_ASCII)));
}
return memStream.toByteArray();
}
} finally {
if (LOGGER.isLoggable(Level.FINE)) {
LOGGER.log(Level.FINE, "Retrieved URL: " + url + ", header fields: " + connection.getHeaderFields());
}
connection.disconnect();
}
}
/*
* helper for logging binary content
*/
private static String replaceInvalidChars(String substring) {
StringBuilder builder = new StringBuilder();
for(char c : substring.toCharArray()) {
if(c < 32) {
builder.append('.');
} else {
builder.append(c);
}
}
return builder.toString();
}
/*
* helper to decide if response is is considered valid for retrieveData.
*/
private static boolean responseCodeValid(int responseCode) {
return responseCode / 100 == HttpURLConnection.HTTP_OK / 100;
}
/*
* Prepare connection by setting connectTimeout and readTimeout to timeout,
* doOutput to false and doInput to true.
*
* Throws IllegalArgumentException on zero (infinite) timeout.
*/
private static void prepareConnection(URLConnection connection, int timeout, SSLSocketFactory sslFactory) {
if (timeout == 0) {
throw new IllegalArgumentException("Zero (infinite) timeouts not permitted");
}
connection.setConnectTimeout(timeout);
connection.setReadTimeout(timeout);
connection.setDoInput(true); // whether we want to read from the connection
connection.setDoOutput(false); // whether we want to write to the connection
if(connection instanceof HttpsURLConnection && sslFactory != null) {
((HttpsURLConnection)connection).setSSLSocketFactory(sslFactory);
}
}
/*
* Write POST request header and body
*/
private static void writePostRequest(URLConnection connection, String postRequestBody, String contentType) throws IOException {
connection.setDoOutput(true); // whether we want to write to the connection
if (contentType != null) {
connection.setRequestProperty("Content-Type", contentType);
}
// Note: Content-Length is set implicitly by URLConnection
try (DataOutputStream out = new DataOutputStream(connection.getOutputStream())) {
out.writeBytes(postRequestBody);
}
}
/**
* Check if the HTTP resource specified by the destination URL is available.
*
* @param destinationUrl the destination URL to check for availability
* @param fireRequest if true a request will be sent to the given URL in addition to opening the
* connection
* @param timeout Timeout in milliseconds after which the call fails because of timeout.
* @return true if a connection could be set up and the response was received
* @throws IllegalArgumentException if the destination URL is invalid
*/
public static boolean isAvailable(String destinationUrl, boolean fireRequest, int timeout) throws IllegalArgumentException {
return isAvailable(destinationUrl, fireRequest, false, timeout);
}
/**
* Check if the HTTP resource specified by the destination URL is available.
*
* @param destinationUrl the destination URL to check for availability
* @param fireRequest if true a request will be sent to the given URL in addition to opening the
* connection
* @param ignoreHTTPSHostCheck if specified true, a HostnameVerifier is registered which accepts all host-names
* during SSL handshake
* @param timeout Timeout in milliseconds after which the call fails because of timeout.
* @return true if a connection could be set up and the response was received
* @throws IllegalArgumentException if the destination URL is invalid
*/
public static boolean isAvailable(String destinationUrl, boolean fireRequest, boolean ignoreHTTPSHostCheck,
int timeout) throws IllegalArgumentException {
return getAccessError(destinationUrl, fireRequest, ignoreHTTPSHostCheck, timeout, null) == null;
}
/**
* Check if the HTTP resource specified by the destination URL is available.
*
* @param destinationUrl the destination URL to check for availability
* @param fireRequest if true a request will be sent to the given URL in addition to opening the
* connection
* @param ignoreHTTPSHostCheck if specified true, a HostnameVerifier is registered which accepts all host-names
* during SSL handshake
* @param timeout Timeout in milliseconds after which the call fails because of timeout.
* @param sslFactory The SSLFactory to use for the connection, this allows to support custom SSL certificates
* @return true if a connection could be set up and the response was received
* @throws IllegalArgumentException if the destination URL is invalid
*/
public static boolean isAvailable(String destinationUrl, boolean fireRequest, boolean ignoreHTTPSHostCheck,
int timeout, SSLSocketFactory sslFactory) throws IllegalArgumentException {
return getAccessError(destinationUrl, fireRequest, ignoreHTTPSHostCheck, timeout, sslFactory) == null;
}
/**
*
* @param destinationUrl the destination URL to check for availability
* @param fireRequest if true a request will be sent to the given URL in addition to opening the
* connection
* @param ignoreHTTPSHostCheck if specified true, a HostnameVerifier is registered which accepts all host-names
* during SSL handshake
* @param timeout Timeout in milliseconds after which the call fails because of timeout.
* @return null if connection works, an error message if some problem happens.
* @throws IllegalArgumentException if the destination URL is invalid
*/
public static String getAccessError(String destinationUrl, boolean fireRequest, boolean ignoreHTTPSHostCheck, int timeout) throws IllegalArgumentException {
return getAccessError(destinationUrl, fireRequest, ignoreHTTPSHostCheck, timeout, null);
}
/**
*
* @param destinationUrl the destination URL to check for availability
* @param fireRequest if true a request will be sent to the given URL in addition to opening the
* connection
* @param ignoreHTTPSHostCheck if specified true, a HostnameVerifier is registered which accepts all host-names
* during SSL handshake
* @param timeout Timeout in milliseconds after which the call fails because of timeout.
* @param sslFactory The SSLFactory to use for the connection, this allows to support custom SSL certificates
* @return null if connection works, an error message if some problem happens.
* @throws IllegalArgumentException if the destination URL is invalid
*/
public static String getAccessError(String destinationUrl, boolean fireRequest, boolean ignoreHTTPSHostCheck, int timeout, SSLSocketFactory sslFactory) throws IllegalArgumentException {
URL url;
try {
url = new URL(destinationUrl);
} catch (MalformedURLException e) {
throw new IllegalArgumentException("Invalid destination URL", e);
}
HttpURLConnection conn = null;
try {
conn = (HttpURLConnection) url.openConnection();
// set specified timeout if non-zero
if(timeout != 0) {
conn.setConnectTimeout(timeout);
conn.setReadTimeout(timeout);
}
if(ignoreHTTPSHostCheck && conn instanceof HttpsURLConnection) {
((HttpsURLConnection)conn).setHostnameVerifier(new AllowingHostnameVerifier());
}
if(conn instanceof HttpsURLConnection && sslFactory != null) {
((HttpsURLConnection)conn).setSSLSocketFactory(sslFactory);
}
conn.setDoOutput(false);
conn.setDoInput(true);
/* if connecting is not possible this will throw a connection refused exception */
conn.connect();
/* dotNet processes require a first request to be sent to initialize the application */
if (fireRequest) {
conn.getInputStream().close();
}
/* if connecting is possible we return true here */
return null;
} catch (IOException e) {
if(LOGGER.isLoggable(Level.FINE)){
LOGGER.fine("Connection attempt to '" + destinationUrl + "' failed. Connection refused.");
}
/* exception is thrown -> server not available */
return e.getClass().getName() + ": " + e.getMessage();
} finally {
if (conn != null) {
conn.disconnect();
}
}
}
}
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