EssentialsUpdate WIP

EssentialsUpdate/src/com/earth2me/essentials/update/GetFile.java

@@ -0,0 +1,112 @@
+package com.earth2me.essentials.update;
+
+import java.io.BufferedInputStream;
+import java.io.BufferedOutputStream;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.math.BigInteger;
+import java.net.HttpURLConnection;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLConnection;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.logging.Logger;
+
+
+public class GetFile
+{
+	private transient URLConnection connection;
+	private transient MessageDigest digest;
+
+	public GetFile(final String urlString) throws MalformedURLException, IOException
+	{
+		final URL url = new URL(urlString);
+		this.connection = url.openConnection();
+		this.connection.setConnectTimeout(1000);
+		this.connection.setReadTimeout(5000);
+		this.connection.setUseCaches(false);
+		this.connection.connect();
+		final int respCode = ((HttpURLConnection)this.connection).getResponseCode();
+		if (respCode >= 300 && respCode < 400 && this.connection.getHeaderField("Location") != null)
+		{
+			connection.getInputStream().close();
+			final URL redirect = new URL(this.connection.getHeaderField("Location"));
+			this.connection = redirect.openConnection();
+			this.connection.setConnectTimeout(1000);
+			this.connection.setReadTimeout(5000);
+			this.connection.setUseCaches(false);
+			this.connection.connect();
+		}
+	}
+
+	public void saveTo(final File file) throws IOException
+	{
+		try
+		{
+			saveTo(file, null);
+		}
+		catch (NoSuchAlgorithmException ex)
+		{
+			// Ignore because the code is never called
+		}
+	}
+
+	public void saveTo(final File file, final String key) throws IOException, NoSuchAlgorithmException
+	{
+		if (key != null)
+		{
+			digest = MessageDigest.getInstance("SHA256");
+		}
+		final byte[] buffer = new byte[1024 * 8];
+		boolean brokenFile = false;
+		final BufferedInputStream input = new BufferedInputStream(connection.getInputStream());
+		try
+		{
+			final BufferedOutputStream output = new BufferedOutputStream(new FileOutputStream(file));
+			try
+			{
+				int length;
+				do
+				{
+					length = input.read(buffer);
+					if (length >= 0)
+					{
+						if (key != null)
+						{
+							digest.update(buffer, 0, length);
+						}
+						output.write(buffer, 0, length);
+					}
+				}
+				while (length >= 0);
+				if (key != null)
+				{
+					final byte[] checksum = digest.digest();
+					final String checksumString = new BigInteger(checksum).toString(36);
+					if (!checksumString.equals(key))
+					{
+						brokenFile = true;
+					}
+				}
+			}
+			finally
+			{
+				output.close();
+			}
+			if (brokenFile && !file.delete())
+			{
+				Logger.getLogger("Minecraft").severe("Could not delete file " + file.getPath());
+			}
+		}
+		finally
+		{
+			input.close();
+		}
+		if (brokenFile)
+		{
+			throw new IOException("Checksum check failed.");
+		}
+	}
+}