Add a streaming Json item reader

build.gradle

@@ -74,6 +74,7 @@ allprojects {
 		hibernateValidatorVersion = '6.0.4.Final'
 		hsqldbVersion = '2.4.0'
 		jackson2Version = '2.9.2'
+		gsonVersion = '2.8.5'
 		javaMailVersion = '1.6.0'
 		javaxBatchApiVersion = '1.0'
 		javaxInjectVersion = '1'
@@ -326,6 +327,7 @@ project('spring-batch-infrastructure') {
 
 		optional "javax.jms:javax.jms-api:$jmsVersion"
 		optional "com.fasterxml.jackson.core:jackson-databind:${jackson2Version}"
+		optional "com.google.code.gson:gson:${gsonVersion}"
 		compile("org.hibernate:hibernate-core:$hibernateVersion") { dep ->
 			optional dep
 			exclude group: 'org.jboss.spec.javax.transaction', module: 'jboss-transaction-api_1.1_spec'

spring-batch-infrastructure-tests/src/test/java/org/springframework/batch/item/json/GsonJsonItemReaderFunctionalTests.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2018 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.json;
+
+import com.google.gson.JsonSyntaxException;
+
+import org.springframework.batch.item.json.domain.Trade;
+
+/**
+ * @author Mahmoud Ben Hassine
+ */
+public class GsonJsonItemReaderFunctionalTests extends JsonItemReaderFunctionalTests {
+
+	@Override
+	protected JsonObjectReader<Trade> getJsonObjectReader() {
+		return new GsonJsonObjectReader<>(Trade.class);
+	}
+
+	@Override
+	protected Class<? extends Exception> getJsonParsingException() {
+		return JsonSyntaxException.class;
+	}
+
+}

spring-batch-infrastructure-tests/src/test/java/org/springframework/batch/item/json/JacksonJsonItemReaderFunctionalTests.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2018 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.json;
+
+import com.fasterxml.jackson.core.JsonParseException;
+
+import org.springframework.batch.item.json.domain.Trade;
+
+/**
+ * @author Mahmoud Ben Hassine
+ */
+public class JacksonJsonItemReaderFunctionalTests extends JsonItemReaderFunctionalTests {
+
+	@Override
+	protected JsonObjectReader<Trade> getJsonObjectReader() {
+		return new JacksonJsonObjectReader<>(Trade.class);
+	}
+
+	@Override
+	protected Class<? extends Exception> getJsonParsingException() {
+		return JsonParseException.class;
+	}
+
+}

spring-batch-infrastructure-tests/src/test/java/org/springframework/batch/item/json/JsonItemReaderFunctionalTests.java

@@ -0,0 +1,118 @@
+/*
+ * Copyright 2018 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.json;
+
+import java.math.BigDecimal;
+
+import org.hamcrest.Matchers;
+import org.junit.Assert;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+import org.springframework.batch.item.ExecutionContext;
+import org.springframework.batch.item.ItemStreamException;
+import org.springframework.batch.item.ParseException;
+import org.springframework.batch.item.json.builder.JsonItemReaderBuilder;
+import org.springframework.batch.item.json.domain.Trade;
+import org.springframework.core.io.ByteArrayResource;
+import org.springframework.core.io.ClassPathResource;
+
+import static org.hamcrest.Matchers.instanceOf;
+
+/**
+ * @author Mahmoud Ben Hassine
+ */
+public abstract class JsonItemReaderFunctionalTests {
+
+	@Rule
+	public ExpectedException expectedException = ExpectedException.none();
+
+	protected abstract JsonObjectReader<Trade> getJsonObjectReader();
+
+	protected abstract Class<? extends Exception> getJsonParsingException();
+
+	@Test
+	public void testJsonReading() throws Exception {
+		JsonItemReader<Trade> itemReader = new JsonItemReaderBuilder<Trade>()
+				.jsonObjectReader(getJsonObjectReader())
+				.resource(new ClassPathResource("org/springframework/batch/item/json/trades.json"))
+				.name("tradeJsonItemReader")
+				.build();
+
+		itemReader.open(new ExecutionContext());
+
+		Trade trade = itemReader.read();
+		Assert.assertNotNull(trade);
+		Assert.assertEquals("123", trade.getIsin());
+		Assert.assertEquals("foo", trade.getCustomer());
+		Assert.assertEquals(new BigDecimal("1.2"), trade.getPrice());
+		Assert.assertEquals(1, trade.getQuantity());
+
+		trade = itemReader.read();
+		Assert.assertNotNull(trade);
+		Assert.assertEquals("456", trade.getIsin());
+		Assert.assertEquals("bar", trade.getCustomer());
+		Assert.assertEquals(new BigDecimal("1.4"), trade.getPrice());
+		Assert.assertEquals(2, trade.getQuantity());
+
+		trade = itemReader.read();
+		Assert.assertNull(trade);
+	}
+
+	@Test
+	public void testEmptyResource() throws Exception {
+		JsonItemReader<Trade> itemReader = new JsonItemReaderBuilder<Trade>()
+				.jsonObjectReader(getJsonObjectReader())
+				.resource(new ByteArrayResource("[]".getBytes()))
+				.name("tradeJsonItemReader")
+				.build();
+
+		itemReader.open(new ExecutionContext());
+
+		Trade trade = itemReader.read();
+		Assert.assertNull(trade);
+	}
+
+	@Test
+	public void testInvalidResourceFormat() {
+		this.expectedException.expect(ItemStreamException.class);
+		this.expectedException.expectMessage("Failed to initialize the reader");
+		this.expectedException.expectCause(instanceOf(IllegalStateException.class));
+		JsonItemReader<Trade> itemReader = new JsonItemReaderBuilder<Trade>()
+				.jsonObjectReader(getJsonObjectReader())
+				.resource(new ByteArrayResource("{}, {}".getBytes()))
+				.name("tradeJsonItemReader")
+				.build();
+
+		itemReader.open(new ExecutionContext());
+	}
+
+	@Test
+	public void testInvalidResourceContent() throws Exception {
+		this.expectedException.expect(ParseException.class);
+		this.expectedException.expectCause(Matchers.instanceOf(getJsonParsingException()));
+		JsonItemReader<Trade> itemReader = new JsonItemReaderBuilder<Trade>()
+				.jsonObjectReader(getJsonObjectReader())
+				.resource(new ByteArrayResource("[{]".getBytes()))
+				.name("tradeJsonItemReader")
+				.build();
+		itemReader.open(new ExecutionContext());
+
+		itemReader.read();
+	}
+}

spring-batch-infrastructure-tests/src/test/java/org/springframework/batch/item/json/domain/Trade.java

@@ -0,0 +1,124 @@
+/*
+ * Copyright 2018 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.json.domain;
+
+import java.math.BigDecimal;
+
+/**
+ * @author Mahmoud Ben Hassine
+ */
+public class Trade {
+
+	private String isin = "";
+
+	private long quantity = 0;
+
+	private BigDecimal price = new BigDecimal(0);
+
+	private String customer = "";
+
+	public Trade() {
+	}
+
+	public Trade(String isin, long quantity, BigDecimal price, String customer) {
+		this.isin = isin;
+		this.quantity = quantity;
+		this.price = price;
+		this.customer = customer;
+	}
+
+	public void setCustomer(String customer) {
+		this.customer = customer;
+	}
+
+	public void setIsin(String isin) {
+		this.isin = isin;
+	}
+
+	public void setPrice(BigDecimal price) {
+		this.price = price;
+	}
+
+	public void setQuantity(long quantity) {
+		this.quantity = quantity;
+	}
+
+	public String getIsin() {
+		return isin;
+	}
+
+	public BigDecimal getPrice() {
+		return price;
+	}
+
+	public long getQuantity() {
+		return quantity;
+	}
+
+	public String getCustomer() {
+		return customer;
+	}
+
+	@Override
+	public String toString() {
+		return "Trade: [isin=" + this.isin + ",quantity=" + this.quantity + ",price=" + this.price + ",customer="
+				+ this.customer + "]";
+	}
+
+	@Override
+	public int hashCode() {
+		final int prime = 31;
+		int result = 1;
+		result = prime * result + ((customer == null) ? 0 : customer.hashCode());
+		result = prime * result + ((isin == null) ? 0 : isin.hashCode());
+		result = prime * result + ((price == null) ? 0 : price.hashCode());
+		result = prime * result + (int) (quantity ^ (quantity >>> 32));
+		return result;
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj)
+			return true;
+		if (obj == null)
+			return false;
+		if (getClass() != obj.getClass())
+			return false;
+		Trade other = (Trade) obj;
+		if (customer == null) {
+			if (other.customer != null)
+				return false;
+		}
+		else if (!customer.equals(other.customer))
+			return false;
+		if (isin == null) {
+			if (other.isin != null)
+				return false;
+		}
+		else if (!isin.equals(other.isin))
+			return false;
+		if (price == null) {
+			if (other.price != null)
+				return false;
+		}
+		else if (!price.equals(other.price))
+			return false;
+		if (quantity != other.quantity)
+			return false;
+		return true;
+	}
+
+}

spring-batch-infrastructure-tests/src/test/resources/org/springframework/batch/item/json/trades.json

@@ -0,0 +1,14 @@
+[
+  {
+    "isin": "123",
+    "quantity": 1,
+    "price": 1.2,
+    "customer": "foo"
+  },
+  {
+    "isin": "456",
+    "quantity": 2,
+    "price": 1.4,
+    "customer": "bar"
+  }
+]