Adds pretty printing and configurable character escapes to the JsonEncoder.

(cherry picking from commit 0b882fe)

Author: cboehme

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

@@ -18,6 +18,7 @@
 import java.io.IOException;
 import java.io.StringWriter;
 
+import org.apache.commons.lang.StringEscapeUtils;
 import org.culturegraph.mf.exceptions.MetafactureException;
 import org.culturegraph.mf.framework.DefaultStreamPipe;
 import org.culturegraph.mf.framework.ObjectReceiver;
@@ -30,13 +31,17 @@
 import com.fasterxml.jackson.core.JsonGenerationException;
 import com.fasterxml.jackson.core.JsonGenerator;
 import com.fasterxml.jackson.core.JsonStreamContext;
+import com.fasterxml.jackson.core.SerializableString;
+import com.fasterxml.jackson.core.io.CharacterEscapes;
+import com.fasterxml.jackson.core.io.SerializedString;
 
 /**
  * Serialises an object as JSON. Records and entities are represented
  * as objects unless their name ends with []. If the name ends with [],
  * an array is created.
- * 
+ *
  * @author Christoph Böhme
+ * @author Michael Büchner
  *
  */
 @Description("Serialises an object as JSON")
@@ -49,7 +54,7 @@ public final class JsonEncoder extends
 
 	private final JsonGenerator jsonGenerator;
 	private final StringWriter writer = new StringWriter();
-	
+
 	public JsonEncoder() {
 		try {
 			jsonGenerator = new JsonFactory().createGenerator(writer);
@@ -58,14 +63,68 @@ public JsonEncoder() {
 			throw new MetafactureException(e);
 		}
 	}
-	
+
+	public void setPrettyPrinting(final boolean prettyPrinting) {
+		if (prettyPrinting) {
+			jsonGenerator.useDefaultPrettyPrinter();
+		} else {
+			jsonGenerator.setPrettyPrinter(null);
+		}
+	}
+
+	public boolean getPrettyPrinting() {
+		return jsonGenerator.getPrettyPrinter() != null;
+	}
+
+	/**
+	 * By default JSON output does only have escaping where it is strictly
+	 * necessary. This is recommended in the most cases. Nevertheless it can
+	 * be sometimes useful to have some more escaping. With this method it is
+	 * possible to use {@link StringEscapeUtils#escapeJavaScript(String)}.
+	 *
+	 * @param escapeCharacters an array which defines which characters should be
+	 *                         escaped and how it will be done. See
+	 *                         {@link CharacterEscapes}. In most cases this should
+	 *                         be null. Use like this:
+	 *                         <pre>{@code int[] esc = CharacterEscapes.standardAsciiEscapesForJSON();
+	 * 	                       // and force escaping of a few others:
+	 * 	                       esc['\''] = CharacterEscapes.ESCAPE_STANDARD;
+	 *                         JsonEncoder.useEscapeJavaScript(esc);
+	 *                         }</pre>
+	 */
+	public void setJavaScriptEscapeChars(final int[] escapeCharacters) {
+
+		final CharacterEscapes ce = new CharacterEscapes() {
+			private static final long serialVersionUID = 1L;
+
+			@Override
+			public int[] getEscapeCodesForAscii() {
+				if (escapeCharacters == null) {
+					return CharacterEscapes.standardAsciiEscapesForJSON();
+				}
+
+				return escapeCharacters;
+			}
+
+			@Override
+			public SerializableString getEscapeSequence(final int ch) {
+				final String chString = Character.toString((char) ch);
+				final String jsEscaped = StringEscapeUtils.escapeJavaScript(chString);
+				return new SerializedString(jsEscaped);
+			}
+
+		};
+
+		jsonGenerator.setCharacterEscapes(ce);
+	}
+
 	@Override
 	public void startRecord(final String id) {
 		final StringBuffer buffer = writer.getBuffer();
 		buffer.delete(0, buffer.length());
 		startGroup(id);
 	}
-	
+
 	@Override
 	public void endRecord() {
 		endGroup();
@@ -76,17 +135,17 @@ public void endRecord() {
 		}
 		getReceiver().process(writer.toString());
 	}
-	
+
 	@Override
 	public void startEntity(final String name) {
 		startGroup(name);
 	}
-	
+
 	@Override
 	public void endEntity() {
 		endGroup();
 	}
-	
+
 	@Override
 	public void literal(final String name, final String value) {
 		try {
@@ -106,7 +165,7 @@ public void literal(final String name, final String value) {
 			throw new MetafactureException(e);
 		}
 	}
-	
+
 	private void startGroup(final String name) {
 		try {
 			final JsonStreamContext ctx = jsonGenerator.getOutputContext();
@@ -128,7 +187,7 @@ private void startGroup(final String name) {
 			throw new MetafactureException(e);
 		}
 	}
-	
+
 	private void endGroup() {
 		try {
 			final JsonStreamContext ctx = jsonGenerator.getOutputContext();
@@ -144,5 +203,5 @@ private void endGroup() {
 			throw new MetafactureException(e);
 		}
 	}
-	
+
 }