Solution for the issues described in #152

src/main/java/org/culturegraph/mf/stream/converter/JsonEncoder.java

@@ -53,7 +53,8 @@ public final class JsonEncoder extends
 	public JsonEncoder() {
 		try {
 			jsonGenerator = new JsonFactory().createGenerator(writer);
-		} catch (IOException e) {
+			jsonGenerator.setRootValueSeparator(null);
+		} catch (final IOException e) {
 			throw new MetafactureException(e);
 		}
 	}
@@ -70,8 +71,8 @@ public void endRecord() {
 		endGroup();
 		try {
 			jsonGenerator.flush();
-		} catch (IOException e) {
-			throw new MetafactureException(e); 
+		} catch (final IOException e) {
+			throw new MetafactureException(e);
 		}
 		getReceiver().process(writer.toString());
 	}
@@ -82,7 +83,7 @@ public void startEntity(final String name) {
 	}
 
 	@Override
-	public void endEntity() {	
+	public void endEntity() {
 		endGroup();
 	}
 
@@ -98,10 +99,10 @@ public void literal(final String name, final String value) {
 			} else {
 				jsonGenerator.writeString(value);
 			}
-		} catch (JsonGenerationException e) {
-			throw new MetafactureException(e); 
+		} catch (final JsonGenerationException e) {
+			throw new MetafactureException(e);
 		}
-		catch (IOException e) {
+		catch (final IOException e) {
 			throw new MetafactureException(e);
 		}
 	}
@@ -113,17 +114,17 @@ private void startGroup(final String name) {
 				if (ctx.inObject()) {
 					jsonGenerator.writeFieldName(name.substring(0, name.length() - ARRAY_MARKER.length()));
 				}
-				jsonGenerator.writeStartArray(); 				
-			} else {		
+				jsonGenerator.writeStartArray();
+			} else {
 				if (ctx.inObject()) {
 					jsonGenerator.writeFieldName(name);
 				}
 				jsonGenerator.writeStartObject();
 			}
-		} catch (JsonGenerationException e) {
-			throw new MetafactureException(e); 
+		} catch (final JsonGenerationException e) {
+			throw new MetafactureException(e);
 		}
-		catch (IOException e) {
+		catch (final IOException e) {
 			throw new MetafactureException(e);
 		}
 	}
@@ -136,10 +137,10 @@ private void endGroup() {
 			} else if (ctx.inArray()) {
 				jsonGenerator.writeEndArray();
 			}
-		} catch (JsonGenerationException e) {
-			throw new MetafactureException(e); 
+		} catch (final JsonGenerationException e) {
+			throw new MetafactureException(e);
 		}
-		catch (IOException e) {
+		catch (final IOException e) {
 			throw new MetafactureException(e);
 		}
 	}

src/main/java/org/culturegraph/mf/stream/sink/AbstractObjectWriter.java

@@ -0,0 +1,62 @@
+/*
+ *  Copyright 2013 Christoph Böhme
+ *
+ *  Licensed 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 org.culturegraph.mf.stream.sink;
+
+/**
+ * Common functions for object writers.
+ * 
+ * @author Christoph Böhme
+ *
+ * @param <T>
+ * 		object type
+ */
+public abstract class AbstractObjectWriter<T> implements ConfigurableObjectWriter<T> {
+
+	private String header = DEFAULT_HEADER;
+	private String footer = DEFAULT_FOOTER;
+	private String separator = DEFAULT_SEPARATOR;
+
+	@Override
+	public final String getHeader() {
+		return header;
+	}
+
+	@Override
+	public final void setHeader(final String header) {
+		this.header = header;
+	}
+
+	@Override
+	public final String getFooter() {
+		return footer;
+	}
+
+	@Override
+	public final void setFooter(final String footer) {
+		this.footer = footer;
+	}
+
+	@Override
+	public final String getSeparator() {
+		return separator;
+	}
+
+	@Override
+	public final void setSeparator(final String separator) {
+		this.separator = separator;
+	}
+
+}

src/main/java/org/culturegraph/mf/stream/sink/ConfigurableObjectWriter.java

@@ -0,0 +1,114 @@
+/*
+ *  Copyright 2013 Christoph Böhme
+ *
+ *  Licensed 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 org.culturegraph.mf.stream.sink;
+
+import org.culturegraph.mf.framework.ObjectReceiver;
+import org.culturegraph.mf.util.FileCompression;
+
+/**
+ * Back end implementations for {@link ObjectWriter} should offer
+ * a default set of configuration options. These are defined by
+ * this interface.
+ * 
+ * @author Christoph Böhme
+ *
+ * @param <T> object type
+ */
+public interface ConfigurableObjectWriter<T> extends ObjectReceiver<T> {
+
+	String DEFAULT_HEADER = "";
+	String DEFAULT_FOOTER = "\n";
+	String DEFAULT_SEPARATOR = "\n";
+
+	/**
+	 * Returns the encoding used by the underlying writer.
+	 * 
+	 * @return current encoding
+	 */
+	String getEncoding();
+
+	/**
+	 * Sets the encoding used by the underlying writer.
+	 * 
+	 * @param encoding
+	 *            name of the encoding
+	 */
+	void setEncoding(String encoding);
+
+	/**
+	 * Returns the compression mode.
+	 * 
+	 * @return current compression mode
+	 */
+	FileCompression getCompression();
+
+	/**
+	 * Sets the compression mode.
+	 * 
+	 * @param compression
+	 */
+	void setCompression(final FileCompression compression);
+
+	/**
+	 * Sets the compression mode.
+	 * 
+	 * @param compression
+	 */
+	void setCompression(final String compression);
+
+	/**
+	 * Returns the header which is output before the first object.
+	 * 
+	 * @return header string
+	 */
+	String getHeader();
+
+	/**
+	 * Sets the header which is output before the first object.
+	 * 
+	 * @param header new header string
+	 */
+	void setHeader(final String header);
+
+	/**
+	 * Returns the footer which is output after the last object.
+	 * 
+	 * @return footer string
+	 */
+	String getFooter();
+
+	/**
+	 * Sets the footer which is output after the last object.
+	 * 
+	 * @param footer new footer string
+	 */
+	void setFooter(final String footer);
+
+	/**
+	 * Returns the separator which is output between objects.
+	 * 
+	 * @return separator string
+	 */
+	String getSeparator();
+
+	/**
+	 * Sets the separator which is output between objects.
+	 * 
+	 * @param separator new separator string
+	 */
+	void setSeparator(final String separator);
+
+}