Add sample app to show MongoDB support

spring-batch-samples/src/main/java/org/springframework/batch/sample/mongodb/JobConfiguration.java

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+/*
+ * Copyright 2020 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
+ *
+ *      https://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.sample.mongodb;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.springframework.batch.core.Job;
+import org.springframework.batch.core.Step;
+import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
+import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
+import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
+import org.springframework.batch.item.data.MongoItemReader;
+import org.springframework.batch.item.data.MongoItemWriter;
+import org.springframework.batch.item.data.builder.MongoItemReaderBuilder;
+import org.springframework.batch.item.data.builder.MongoItemWriterBuilder;
+import org.springframework.context.annotation.Bean;
+import org.springframework.data.domain.Sort;
+import org.springframework.data.mongodb.core.MongoTemplate;
+
+/**
+ *  This sample job will copy data from collection "person_in" into collection "person_out"
+ *  using {@link MongoItemReader} and {@link MongoItemWriter}.
+ *
+ *  @author Mahmoud Ben Hassine
+ */
+@EnableBatchProcessing
+public class JobConfiguration {
+
+	private JobBuilderFactory jobBuilderFactory;
+
+	private StepBuilderFactory stepBuilderFactory;
+
+	public JobConfiguration(JobBuilderFactory jobBuilderFactory, StepBuilderFactory stepBuilderFactory) {
+		this.jobBuilderFactory = jobBuilderFactory;
+		this.stepBuilderFactory = stepBuilderFactory;
+	}
+
+	@Bean
+	public MongoItemReader<Person> mongoItemReader(MongoTemplate mongoTemplate) {
+		Map<String, Sort.Direction> sortOptions = new HashMap<>();
+		sortOptions.put("name", Sort.Direction.DESC);
+		return new MongoItemReaderBuilder<Person>()
+				.name("personItemReader")
+				.collection("person_in")
+				.targetType(Person.class)
+				.template(mongoTemplate)
+				.jsonQuery("{}")
+				.sorts(sortOptions)
+				.build();
+	}
+
+	@Bean
+	public MongoItemWriter<Person> mongoItemWriter(MongoTemplate mongoTemplate) {
+		return new MongoItemWriterBuilder<Person>()
+				.template(mongoTemplate)
+				.collection("person_out")
+				.build();
+	}
+
+	@Bean
+	public Step step(MongoItemReader<Person> mongoItemReader, MongoItemWriter<Person> mongoItemWriter) {
+		return this.stepBuilderFactory.get("step")
+				.<Person, Person>chunk(2)
+				.reader(mongoItemReader)
+				.writer(mongoItemWriter)
+				.build();
+	}
+
+	@Bean
+	public Job job(Step step) {
+		return this.jobBuilderFactory.get("job")
+				.start(step)
+				.build();
+	}
+
+}

spring-batch-samples/src/main/java/org/springframework/batch/sample/mongodb/MongoDBConfiguration.java

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+/*
+ * Copyright 2020 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
+ *
+ *      https://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.sample.mongodb;
+
+import com.mongodb.client.MongoClient;
+import com.mongodb.client.MongoClients;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.PropertySource;
+import org.springframework.data.mongodb.core.MongoTemplate;
+
+@Configuration
+@PropertySource("classpath:/mongodb-sample.properties")
+public class MongoDBConfiguration {
+
+	@Value("${mongodb.host}")
+	private String mongodbHost;
+
+	@Value("${mongodb.port}")
+	private int mongodbPort;
+
+	@Value("${mongodb.database}")
+	private String mongodbDatabase;
+
+	@Bean
+	public MongoTemplate mongoTemplate() {
+		String connectionString = "mongodb://" +
+				this.mongodbHost + ":" + this.mongodbPort + "/" + this.mongodbDatabase;
+		MongoClient mongoClient = MongoClients.create(connectionString);
+		return new MongoTemplate(mongoClient, "test");
+	}
+
+}

spring-batch-samples/src/main/java/org/springframework/batch/sample/mongodb/MongoDBSampleApp.java

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+/*
+ * Copyright 2020 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
+ *
+ *      https://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.sample.mongodb;
+
+import java.util.Arrays;
+import java.util.List;
+
+import com.mongodb.client.MongoCollection;
+import org.bson.Document;
+
+import org.springframework.batch.core.Job;
+import org.springframework.batch.core.JobParameters;
+import org.springframework.batch.core.launch.JobLauncher;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.data.mongodb.core.MongoTemplate;
+
+/**
+ * Ensure a MongoDB instance is running on "localhost:27017",
+ * otherwise modify mongodb-sample.properties file as needed.
+ *
+ * If you use docker, you can run a mongo db server with:
+ * "docker run --name mongodb --rm -d -p 27017:27017 mongo"
+ *
+ * @author Mahmoud Ben Hassine
+ */
+public class MongoDBSampleApp {
+
+	public static void main(String[] args) throws Exception {
+		Class<?>[] configurationClasses = {JobConfiguration.class, MongoDBConfiguration.class};
+		ApplicationContext context = new AnnotationConfigApplicationContext(configurationClasses);
+		MongoTemplate mongoTemplate = context.getBean(MongoTemplate.class);
+
+		// clear collections and insert some documents in "person_in"
+		MongoCollection<Document> personsIn = mongoTemplate.getCollection("person_in");
+		MongoCollection<Document> personsOut = mongoTemplate.getCollection("person_out");
+		personsIn.deleteMany(new Document());
+		personsOut.deleteMany(new Document());
+		personsIn.insertMany(Arrays.asList(
+				new Document("name", "foo1"),
+				new Document("name", "foo2"),
+				new Document("name", "foo3"),
+				new Document("name", "foo4"))
+		);
+
+		// run the job
+		JobLauncher jobLauncher = context.getBean(JobLauncher.class);
+		Job job = context.getBean(Job.class);
+		jobLauncher.run(job, new JobParameters());
+
+		// check results
+		List<Person> persons = mongoTemplate.findAll(Person.class, "person_out");
+		System.out.println("Checking persons in person_out collection");
+		for (Person person : persons) {
+			System.out.println(person);
+		}
+	}
+}

spring-batch-samples/src/main/java/org/springframework/batch/sample/mongodb/Person.java

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+/*
+ * Copyright 2020 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
+ *
+ *      https://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.sample.mongodb;
+
+public class Person {
+    
+    private String name;
+
+    public Person() {
+    }
+
+    public Person(String name) {
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    @Override
+    public String toString() {
+        return "Person{" +
+                "name='" + name + '\'' +
+                '}';
+    }
+}

spring-batch-samples/src/main/resources/mongodb-sample.properties

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+mongodb.host=127.0.0.1
+mongodb.port=27017
+mongodb.database=test