IN PROGRESS - issue BATCH-1246: Add support for a JSON Reader from text files which are JSON formatted

Added line mapper and record separator using Jackson to parse the line up to a map.

spring-batch-infrastructure/pom.xml

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
 	<modelVersion>4.0.0</modelVersion>
 	<artifactId>spring-batch-infrastructure</artifactId>
 	<version>2.1.0.CI-SNAPSHOT </version>
@@ -100,6 +101,12 @@
 			<artifactId>commons-io</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.codehaus.jackson</groupId>
+			<artifactId>jackson-mapper-asl</artifactId>
+			<version>1.0.1</version>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>hsqldb</groupId>
 			<artifactId>hsqldb</artifactId>

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/file/separator/DefaultRecordSeparatorPolicy.java

@@ -119,8 +119,8 @@ public class DefaultRecordSeparatorPolicy extends SimpleRecordSeparatorPolicy {
 	}
 
 	/**
-	 * Determine if the current line (or buffered concatenation of lines)
-	 * contains an unterminated quote, indicating that the record is continuing
+	 * Determine if the current line (or buffered concatenation of lines) ends
+	 * with the continuation marker, indicating that the record is continuing
 	 * onto the next line.
 	 * 
 	 * @param result

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/file/separator/JsonRecordSeparatorPolicy.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2006-2007 the original author or authors.
+ *
+ * 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.springframework.batch.item.file.separator;
+
+import org.springframework.util.StringUtils;
+
+/**
+ * JSON-based record separator. Waits for a valid JSON object before returning a
+ * complete line. A valid object has balanced braces ({}), possibly nested, and
+ * ends with a closing brace. This separator can be used to split a stream into
+ * JSON objects, even if those objects are spread over multiple lines, e.g.
+ * 
+ * <pre>
+ * {"foo": "bar",
+ *  "value": { "spam": 2 }}
+ *  {"foo": "rab",
+ *  "value": { "spam": 3, "foo": "bar" }}
+ * </pre>
+ * 
+ * @author Dave Syer
+ * 
+ */
+public class JsonRecordSeparatorPolicy extends SimpleRecordSeparatorPolicy {
+
+	/**
+	 * True if the line can be parsed to a JSON object.
+	 * 
+	 * @see RecordSeparatorPolicy#isEndOfRecord(String)
+	 */
+	public boolean isEndOfRecord(String line) {
+		return StringUtils.countOccurrencesOf(line, "{") == StringUtils.countOccurrencesOf(line, "}")
+				&& line.trim().endsWith("}");
+	}
+
+}

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/file/transform/JsonLineMapper.java

@@ -0,0 +1,52 @@
+package org.springframework.batch.item.file.transform;
+
+import java.util.Map;
+
+import org.codehaus.jackson.JsonParser;
+import org.codehaus.jackson.map.MappingJsonFactory;
+import org.springframework.batch.item.file.FlatFileParseException;
+import org.springframework.batch.item.file.LineMapper;
+
+/**
+ * Interpret a line as a Json object and parse it up to a Map. The line should
+ * be a standard Json object, starting with "{" and ending with "}" and composed
+ * of <code>name:value</code> pairs separated by commas. Whitespace is ignored,
+ * e.g.
+ * 
+ * <pre>
+ * { "foo" : "bar", "value" : 123 }
+ * </pre>
+ * 
+ * The values can also be Json objects (which are converted to maps):
+ * 
+ * <pre>
+ * { "foo": "bar", "map": { "one": 1, "two": 2}}
+ * </pre>
+ * 
+ * @author Dave Syer
+ * 
+ */
+public class JsonLineMapper implements LineMapper<Map<String, Object>> {
+
+	private MappingJsonFactory factory = new MappingJsonFactory();
+
+	/**
+	 * Interpret the line as a Json object and create a Map from it.  
+	 * 
+	 * @see LineMapper#mapLine(String, int)
+	 */
+	public Map<String, Object> mapLine(String line, int lineNumber) throws Exception {
+		Map<String, Object> result;
+		try {
+			JsonParser parser = factory.createJsonParser(line);
+			@SuppressWarnings("unchecked")
+			Map<String, Object> token = parser.readValueAs(Map.class);
+			result = token;
+		}
+		catch (Exception e) {
+			throw new FlatFileParseException("Cannot parse line to JSON", e, line, lineNumber);
+		}
+		return result;
+	}
+
+}

spring-batch-infrastructure/src/test/java/org/springframework/batch/item/file/separator/JsonRecordSeparatorPolicyTests.java

@@ -0,0 +1,23 @@
+package org.springframework.batch.item.file.separator;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+public class JsonRecordSeparatorPolicyTests {
+	
+	private JsonRecordSeparatorPolicy policy = new JsonRecordSeparatorPolicy();
+
+	@Test
+	public void testIsEndOfRecord() {
+		assertFalse(policy.isEndOfRecord("{\"a\":\"b\""));
+		assertTrue(policy.isEndOfRecord("{\"a\":\"b\"} "));
+	}
+
+	@Test
+	public void testNestedObject() {
+		assertFalse(policy.isEndOfRecord("{\"a\": {\"b\": 2}"));
+		assertTrue(policy.isEndOfRecord("{\"a\": {\"b\": 2}} "));
+	}
+
+}

spring-batch-infrastructure/src/test/java/org/springframework/batch/item/file/transform/JsonLineMapperTests.java

@@ -0,0 +1,34 @@
+package org.springframework.batch.item.file.transform;
+
+import static org.junit.Assert.*;
+
+import java.util.Map;
+
+import org.junit.Test;
+import org.springframework.batch.item.file.FlatFileParseException;
+
+public class JsonLineMapperTests {
+	
+	private JsonLineMapper mapper = new JsonLineMapper();
+
+	@Test
+	public void testMapLine() throws Exception {
+		Map<String, Object> map = mapper.mapLine("{\"foo\": 1}", 1);
+		assertEquals(1, map.get("foo"));
+	}
+
+	@SuppressWarnings("unchecked")
+	@Test
+	public void testMapNested() throws Exception {
+		Map<String, Object> map = mapper.mapLine("{\"foo\": 1, \"bar\" : {\"foo\": 2}}", 1);
+		assertEquals(1, map.get("foo"));
+		assertEquals(2, ((Map<String, Object>) map.get("bar")).get("foo"));
+	}
+
+	@Test(expected=FlatFileParseException.class)
+	public void testMappingError() throws Exception {
+		Map<String, Object> map = mapper.mapLine("{\"foo\": 1", 1);
+		assertEquals(1, map.get("foo"));
+	}
+
+}