Logging character reader that acts like a T.

src/altk/common/engine/util/LoggingInputStreamReader.java

@@ -0,0 +1,94 @@
+package altk.common.engine.util;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.CharBuffer;
+import java.nio.charset.CharsetDecoder;
+
+import org.apache.log4j.Logger;
+
+/**
+ * Wrapper of InputStreamReader to add logging capability.
+ * @author Yuk-Ming
+ *
+ */
+public class LoggingInputStreamReader extends InputStreamReader
+{
+    private static final int CharBuffer_SIZE = 200;
+    
+    private CharBuffer buf = CharBuffer.allocate(CharBuffer_SIZE);
+    
+    private static Logger myLogger = Logger.getLogger(LoggingInputStreamReader.class);
+    
+    private Logger isLogger;
+    
+    public LoggingInputStreamReader(InputStream in, CharsetDecoder decoder, Logger isLogger)
+    {
+        super(in, decoder);
+        this.isLogger = isLogger;
+    }
+
+    
+    @Override
+    public int read() throws IOException
+    {
+        int c = super.read();
+        if (c != -1)
+        {
+            append((char)c);
+        }
+        return c;
+    }
+    
+    @Override
+    public int read(char[] cbuf, int offset, int length) throws IOException
+    {
+        int n = super.read(cbuf, offset, length);
+        for (int i = offset; i < offset + n; i++)
+        {
+            append(cbuf[i]);
+        }
+        return n;
+    }
+
+
+    private void append(char c)
+    {
+        if ((char)c == '\n')
+        {
+            logPartial();
+        }
+        else
+        {
+            buf.put((char)c);
+            if (!buf.hasRemaining()) logPartial();  
+        }
+    }
+
+
+    private void logPartial()
+    {
+        if (buf.position() == 0) return;
+        String logContent = new String(buf.array(), 0, buf.position());
+        isLogger.info(logContent);
+        buf.clear();
+    }
+    
+    @Override
+    public void close()
+    {
+        // Read any remaining characters for logging purpose.
+        try
+        {
+            while (read() != -1);
+            super.close();
+            logPartial();
+        }
+        catch (IOException e)
+        {
+            logPartial();
+            myLogger.warn("Caught exception while reaading unwanted trailing chars in stream");
+        }
+    }
+}