svn commit: r631348 - /incubator/abdera/java/trunk/extensions/json/src/main/java/org/apache/abdera/ext/json/JSONFilter.java

[jm...@apache.org]

Author: jmsnell
Date: Tue Feb 26 11:32:02 2008
New Revision: 631348

URL: http://svn.apache.org/viewvc?rev=631348&view=rev
Log:
filter implementation that optionally converts an Atom document to json

Added:
    incubator/abdera/java/trunk/extensions/json/src/main/java/org/apache/abdera/ext/json/JSONFilter.java

Added: incubator/abdera/java/trunk/extensions/json/src/main/java/org/apache/abdera/ext/json/JSONFilter.java
URL: http://svn.apache.org/viewvc/incubator/abdera/java/trunk/extensions/json/src/main/java/org/apache/abdera/ext/json/JSONFilter.java?rev=631348&view=auto
==============================================================================
--- incubator/abdera/java/trunk/extensions/json/src/main/java/org/apache/abdera/ext/json/JSONFilter.java (added)
+++ incubator/abdera/java/trunk/extensions/json/src/main/java/org/apache/abdera/ext/json/JSONFilter.java Tue Feb 26 11:32:02 2008
@@ -0,0 +1,120 @@
+/*
+* Licensed to the Apache Software Foundation (ASF) under one or more
+* contributor license agreements.  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.  For additional information regarding
+* copyright in this work, please see the NOTICE file in the top level
+* directory of this distribution.
+*/
+package org.apache.abdera.ext.json;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+
+import org.apache.abdera.Abdera;
+import org.apache.abdera.model.Document;
+import org.apache.abdera.model.Element;
+import org.apache.abdera.protocol.server.Filter;
+import org.apache.abdera.protocol.server.FilterChain;
+import org.apache.abdera.protocol.server.ProviderHelper;
+import org.apache.abdera.protocol.server.RequestContext;
+import org.apache.abdera.protocol.server.ResponseContext;
+import org.apache.abdera.protocol.server.context.ResponseContextWrapper;
+import org.apache.abdera.writer.Writer;
+
+/**
+ * Filter implementation that will convert an Atom document returned by
+ * the server into a JSON document if the request specifies a higher
+ * preference value for JSON or explicitly requests JSON by including
+ * a format=json querystring parameter
+ */
+public class JSONFilter 
+  implements Filter {
+  
+  public ResponseContext filter(
+    RequestContext request, 
+    FilterChain chain) {
+      ResponseContext resp = chain.next(request);
+      String format = request.getParameter("format");
+      return jsonPreferred(request,resp.getContentType().toString()) ||
+        (format != null && format.equalsIgnoreCase("json")) ?
+        new JsonResponseContext(resp,request.getAbdera()) :
+        resp;
+  }
+  
+  private boolean jsonPreferred(RequestContext request, String type) {
+    return ProviderHelper.isPreferred(
+      request,
+      "application/json",
+      type);
+  }
+  
+  private class JsonResponseContext 
+    extends ResponseContextWrapper {
+
+    private final Abdera abdera;
+    
+    public JsonResponseContext(
+      ResponseContext response,
+      Abdera abdera) {
+        super(response);
+        setContentType("application/json");
+        this.abdera = abdera;
+    }
+    
+    public void writeTo(
+      OutputStream out, 
+      Writer writer)
+        throws IOException {
+      try {
+        toJson(out,writer);
+      } catch (Exception se) {
+        if (se instanceof RuntimeException)
+          throw (RuntimeException)se;
+        throw new RuntimeException(se);
+      }
+    }
+    
+    public void writeTo(
+      OutputStream out) 
+        throws IOException {
+      try {
+        toJson(out,null);
+      } catch (Exception se) {
+        if (se instanceof RuntimeException)
+          throw (RuntimeException)se;
+        throw new RuntimeException(se);
+      }
+    }
+    
+    private void toJson(OutputStream aout,Writer writer) throws Exception {
+      Document<Element> doc = null;
+      try {
+        ByteArrayOutputStream out = new ByteArrayOutputStream();
+        if (writer == null)
+          super.writeTo(out);
+        else 
+          super.writeTo(out,writer);
+        ByteArrayInputStream in = new ByteArrayInputStream(out.toByteArray());
+        doc = abdera.getParser().parse(in);
+      } catch (Exception e) {}
+      if (doc != null) {
+        doc.writeTo("json",aout);
+      } else {
+        throw new RuntimeException(
+          "There was an error serializing the entry to JSON");
+      }
+    }
+  }
+}