Add 'asset' URLConnection; IOUtil uses URLConnection / incr. effeciency; Android ClassLoaderUtil cleanup;

- Add 'asset' URLConnection
  - Please read API doc 'PiggybackURLConnection' and 'AssetURLConnection'

  - Solves generic resource handling where platform locations may differ,
    ie ClassLoader lookup on Android in the 'assets/' subfolder.

  - New Android 'AssetDexClassLoader' uses 'assets/' folder for findResource(..)

  - aapt.signed (our APK ant task)
    - uses 'assets/' folder

    - adds the 'assetsdir' attribute allowing to copy other assets into the APK

- IOUtil uses URLConnection / incr. effeciency
  - using URLConnection on all getResource(..) since URL
    is connected anyways for validation and URLConnection can be used by caller right away

  - String getRelativeOf(URL, String) -> URL getRelativeOf(URL, String)
    - preserves scheme, authority, etc
    - simple parentOf handling, more efficient

  - reusing new 'asset' protocol impl.

- Android ClassLoaderUtil cleanup;
  - Use createClassLoader(..) impl for build-in static jogamp and user APKs,
    which removes code redundancy

Tests: New code path, especially 'assets' are covered by new unit tests, no regressions on Linux.

1 files changed, 84 insertions, 0 deletions

diff --git a/src/java/com/jogamp/common/net/PiggybackURLConnection.java b/src/java/com/jogamp/common/net/PiggybackURLConnection.java
new file mode 100644
index 0000000..39f1637
--- /dev/null
+++ b/src/java/com/jogamp/common/net/PiggybackURLConnection.java
@@ -0,0 +1,84 @@
+package com.jogamp.common.net;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URL;
+import java.net.URLConnection;
+
+/**
+ * Generic resource location protocol connection, 
+ * using another sub-protocol as the vehicle for a piggyback protocol.
+ * <p>
+ * The details of the sub-protocol can be queried using {@link #getSubProtocol()}. 
+ * </p>
+ * <p>
+ * See example in {@link AssetURLConnection}.
+ * </p>
+ */
+public abstract class PiggybackURLConnection<I extends PiggybackURLContext> extends URLConnection {
+    protected URL subUrl;
+    protected URLConnection subConn;
+    protected I context;
+    
+    /**
+     * @param url the specific URL for this instance
+     * @param context the piggyback context, defining state independent code and constants
+     */
+    protected PiggybackURLConnection(URL url, I context) {
+        super(url);
+        this.context = context;
+    }
+
+    /**
+     * <p>
+     * Resolves the URL via {@link PiggybackURLContext#resolve(String)},
+     * see {@link AssetURLContext#resolve(String)} for an example.
+     * </p>
+     * 
+     * {@inheritDoc}
+     */
+    @Override
+    public synchronized void connect() throws IOException {
+        if(!connected) {
+            subConn = context.resolve(url.getPath());                        
+            subUrl = subConn.getURL(); 
+            connected = true;
+        }
+    }
+    
+    @Override
+    public InputStream getInputStream() throws IOException {
+        if(!connected) {
+            throw new IOException("not connected");
+        }
+        return subConn.getInputStream();
+    }
+    
+    /** 
+     * Returns the <i>entry name</i> of the asset.
+     * <pre>
+     * Plain     asset:test/lala.txt
+     * Resolved  asset:jar:file:/data/app/jogamp.test.apk!/assets/test/lala.txt
+     * Result          test/lala.txt
+     * </pre> 
+     * @throws IOException is not connected
+     **/
+    public abstract String getEntryName() throws IOException;
+    
+    /** 
+     * Returns the resolved <i>sub protocol</i> of the asset or null, ie:
+     * <pre>
+     * Plain     asset:test/lala.txt
+     * Resolved  asset:jar:file:/data/app/jogamp.test.apk!/assets/test/lala.txt
+     * Result          jar:file:/data/app/jogamp.test.apk!/assets/test/lala.txt
+     * </pre>
+     * 
+     * @throws IOException is not connected
+     */
+    public URL getSubProtocol() throws IOException {
+        if(!connected) {
+            throw new IOException("not connected");
+        }
+        return subUrl;
+    }
+}