aboutsummaryrefslogtreecommitdiffstats
path: root/src/eu/siacs/conversations/utils/zlib
diff options
context:
space:
mode:
authorRene Treffer <treffer@measite.de>2014-04-03 18:16:14 +0200
committerRene Treffer <treffer@measite.de>2014-04-03 18:37:25 +0200
commit9502ff25dd6c32c92d356baaaa1640fe26314595 (patch)
tree7767f2193bd2233b3275db2342c36d6e08eeac4f /src/eu/siacs/conversations/utils/zlib
parent2506ef82df6369fef71e00e891b2a2c69330ff94 (diff)
Add compression support
Diffstat (limited to 'src/eu/siacs/conversations/utils/zlib')
-rw-r--r--src/eu/siacs/conversations/utils/zlib/ZLibInputStream.java52
-rw-r--r--src/eu/siacs/conversations/utils/zlib/ZLibOutputStream.java89
2 files changed, 141 insertions, 0 deletions
diff --git a/src/eu/siacs/conversations/utils/zlib/ZLibInputStream.java b/src/eu/siacs/conversations/utils/zlib/ZLibInputStream.java
new file mode 100644
index 00000000..2eebf6f4
--- /dev/null
+++ b/src/eu/siacs/conversations/utils/zlib/ZLibInputStream.java
@@ -0,0 +1,52 @@
+package eu.siacs.conversations.utils.zlib;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.zip.Inflater;
+import java.util.zip.InflaterInputStream;
+
+/**
+ * ZLibInputStream is a zlib and input stream compatible version of an
+ * InflaterInputStream. This class solves the incompatibility between
+ * {@link InputStream#available()} and {@link InflaterInputStream#available()}.
+ */
+public class ZLibInputStream extends InflaterInputStream {
+
+ /**
+ * Construct a ZLibInputStream, reading data from the underlying stream.
+ *
+ * @param is The {@code InputStream} to read data from.
+ * @throws IOException If an {@code IOException} occurs.
+ */
+ public ZLibInputStream(InputStream is) throws IOException {
+ super(is, new Inflater(), 512);
+ }
+
+ /**
+ * Provide a more InputStream compatible version of available.
+ * A return value of 1 means that it is likly to read one byte without
+ * blocking, 0 means that the system is known to block for more input.
+ *
+ * @return 0 if no data is available, 1 otherwise
+ * @throws IOException
+ */
+ @Override
+ public int available() throws IOException {
+ /* This is one of the funny code blocks.
+ * InflaterInputStream.available violates the contract of
+ * InputStream.available, which breaks kXML2.
+ *
+ * I'm not sure who's to blame, oracle/sun for a broken api or the
+ * google guys for mixing a sun bug with a xml reader that can't handle
+ * it....
+ *
+ * Anyway, this simple if breaks suns distorted reality, but helps
+ * to use the api as intended.
+ */
+ if (inf.needsInput()) {
+ return 0;
+ }
+ return super.available();
+ }
+
+}
diff --git a/src/eu/siacs/conversations/utils/zlib/ZLibOutputStream.java b/src/eu/siacs/conversations/utils/zlib/ZLibOutputStream.java
new file mode 100644
index 00000000..f2bff9fd
--- /dev/null
+++ b/src/eu/siacs/conversations/utils/zlib/ZLibOutputStream.java
@@ -0,0 +1,89 @@
+package eu.siacs.conversations.utils.zlib;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.security.NoSuchAlgorithmException;
+import java.util.zip.Deflater;
+import java.util.zip.DeflaterOutputStream;
+
+/**
+ * <p>Android 2.2 includes Java7 FLUSH_SYNC option, which will be used by this
+ * Implementation, preferable via reflection. The @hide was remove in API level
+ * 19. This class might thus go away in the future.</p>
+ * <p>Please use {@link ZLibOutputStream#SUPPORTED} to check for flush
+ * compatibility.</p>
+ */
+public class ZLibOutputStream extends DeflaterOutputStream {
+
+ /**
+ * The reflection based flush method.
+ */
+
+ private final static Method method;
+ /**
+ * SUPPORTED is true if a flush compatible method exists.
+ */
+ public final static boolean SUPPORTED;
+
+ /**
+ * Static block to initialize {@link #SUPPORTED} and {@link #method}.
+ */
+ static {
+ Method m = null;
+ try {
+ m = Deflater.class.getMethod("deflate", byte[].class, int.class, int.class, int.class);
+ } catch (SecurityException e) {
+ } catch (NoSuchMethodException e) {
+ }
+ method = m;
+ SUPPORTED = (method != null);
+ }
+
+ /**
+ * Create a new ZLib compatible output stream wrapping the given low level
+ * stream. ZLib compatiblity means we will send a zlib header.
+ * @param os OutputStream The underlying stream.
+ * @throws IOException In case of a lowlevel transfer problem.
+ * @throws NoSuchAlgorithmException In case of a {@link Deflater} error.
+ */
+ public ZLibOutputStream(OutputStream os) throws IOException,
+ NoSuchAlgorithmException {
+ super(os, new Deflater(Deflater.BEST_COMPRESSION));
+ }
+
+ /**
+ * Flush the given stream, preferring Java7 FLUSH_SYNC if available.
+ * @throws IOException In case of a lowlevel exception.
+ */
+ @Override
+ public void flush() throws IOException {
+ if (!SUPPORTED) {
+ super.flush();
+ return;
+ }
+ int count = 0;
+ if (!def.needsInput()) {
+ do {
+ count = def.deflate(buf, 0, buf.length);
+ out.write(buf, 0, count);
+ } while (count > 0);
+ out.flush();
+ }
+ try {
+ do {
+ count = (Integer) method.invoke(def, buf, 0, buf.length, 2);
+ out.write(buf, 0, count);
+ } while (count > 0);
+ } catch (IllegalArgumentException e) {
+ throw new IOException("Can't flush");
+ } catch (IllegalAccessException e) {
+ throw new IOException("Can't flush");
+ } catch (InvocationTargetException e) {
+ throw new IOException("Can't flush");
+ }
+ super.flush();
+ }
+
+}