Java: introducing websocket support.

src/java/nginx/unit/websocket/pojo/PojoMessageHandlerBase.java

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package nginx.unit.websocket.pojo;
+
+import java.io.IOException;
+import java.lang.reflect.Method;
+import java.nio.ByteBuffer;
+
+import javax.websocket.EncodeException;
+import javax.websocket.MessageHandler;
+import javax.websocket.RemoteEndpoint;
+import javax.websocket.Session;
+
+import org.apache.tomcat.util.ExceptionUtils;
+import nginx.unit.websocket.WrappedMessageHandler;
+
+/**
+ * Common implementation code for the POJO message handlers.
+ *
+ * @param <T>   The type of message to handle
+ */
+public abstract class PojoMessageHandlerBase<T>
+        implements WrappedMessageHandler {
+
+    protected final Object pojo;
+    protected final Method method;
+    protected final Session session;
+    protected final Object[] params;
+    protected final int indexPayload;
+    protected final boolean convert;
+    protected final int indexSession;
+    protected final long maxMessageSize;
+
+    public PojoMessageHandlerBase(Object pojo, Method method,
+            Session session, Object[] params, int indexPayload, boolean convert,
+            int indexSession, long maxMessageSize) {
+        this.pojo = pojo;
+        this.method = method;
+        // TODO: The method should already be accessible here but the following
+        // code seems to be necessary in some as yet not fully understood cases.
+        try {
+            this.method.setAccessible(true);
+        } catch (Exception e) {
+            // It is better to make sure the method is accessible, but
+            // ignore exceptions and hope for the best
+        }
+        this.session = session;
+        this.params = params;
+        this.indexPayload = indexPayload;
+        this.convert = convert;
+        this.indexSession = indexSession;
+        this.maxMessageSize = maxMessageSize;
+    }
+
+
+    protected final void processResult(Object result) {
+        if (result == null) {
+            return;
+        }
+
+        RemoteEndpoint.Basic remoteEndpoint = session.getBasicRemote();
+        try {
+            if (result instanceof String) {
+                remoteEndpoint.sendText((String) result);
+            } else if (result instanceof ByteBuffer) {
+                remoteEndpoint.sendBinary((ByteBuffer) result);
+            } else if (result instanceof byte[]) {
+                remoteEndpoint.sendBinary(ByteBuffer.wrap((byte[]) result));
+            } else {
+                remoteEndpoint.sendObject(result);
+            }
+        } catch (IOException | EncodeException ioe) {
+            throw new IllegalStateException(ioe);
+        }
+    }
+
+
+    /**
+     * Expose the POJO if it is a message handler so the Session is able to
+     * match requests to remove handlers if the original handler has been
+     * wrapped.
+     */
+    @Override
+    public final MessageHandler getWrappedHandler() {
+        if (pojo instanceof MessageHandler) {
+            return (MessageHandler) pojo;
+        } else {
+            return null;
+        }
+    }
+
+
+    @Override
+    public final long getMaxMessageSize() {
+        return maxMessageSize;
+    }
+
+
+    protected final void handlePojoMethodException(Throwable t) {
+        t = ExceptionUtils.unwrapInvocationTargetException(t);
+        ExceptionUtils.handleThrowable(t);
+        if (t instanceof RuntimeException) {
+            throw (RuntimeException) t;
+        } else {
+            throw new RuntimeException(t.getMessage(), t);
+        }
+    }
+}