JSR 352 API framework introduction and usage guide
JSR 352 API framework introduction and usage guide
JSR 352 is a specification in Java. It defines a set of API framework for development and management batch processing applications.This article will introduce the basic concepts of JSR 352, the main components, and how to use this framework to develop batch processing applications.
1. The basic concept of JSR 352
JSR 352 defines the programming model of batch applications and related APIs.Batch processing is a way to deal with a series of similar tasks as a whole.JSR 352 provides a standardized way to write and run such applications.
2. Main components
JSR 352 provides several main components for organizing and managing batch processing applications.These components include:
-JOB: A independent unit of batch processing applications, which consists of a series of tasks.
-STEP: a sub -task of job, it can be executed independently and can have its own input and output.
-CHUNK: a basic processing unit of STEP, it processs a certain amount of data to be processed.
-Tem: Each input and output unit of Chunk can be any Java object.
-JobContext: The context of the Job execution process.
-StepContext: The context of the STEP execution process.
3. Use Guide
The first step of the development batch application is to create a job.You can use the following code to create a simple job:
import javax.batch.runtime.JobExecution;
import javax.batch.runtime.JobInstance;
import javax.batch.runtime.BatchRuntime;
public class MyBatchApplication {
public static void main(String[] args) {
JobExecution jobExecution = BatchRuntime.getJobOperator().start("myJob", null);
long jobId = jobExecution.getJobId();
JobInstance jobInstance = jobExecution.getJobInstance();
System.out.println("Job ID: " + jobId);
System.out.println("Job Instance ID: " + jobInstance.getInstanceId());
}
}
In the above code, we use the Getjoboprator method of the BatchRuntime class to obtain the jobpoperator instance and call the start method to start a job.The start method accepts two parameters. The first parameter is the name of JOB, and the second parameter is a Properties object to pass the parameters of JOB.
To add Step and Chunk, you can use the following code:
import javax.batch.api.AbstractStep;
import javax.batch.api.chunk.AbstractItemReader;
import javax.batch.api.chunk.AbstractItemProcessor;
import javax.batch.api.chunk.AbstractItemWriter;
public class MyStep extends AbstractStep {
@Override
public void start() throws Exception {
setReader(new MyItemReader());
setProcessor(new MyItemProcessor());
setWriter(new MyItemWriter());
}
}
public class MyItemReader extends AbstractItemReader {
@Override
public Object readItem() throws Exception {
// Read a item from the data source
return null;
}
}
public class MyItemProcessor extends AbstractItemProcessor {
@Override
public Object processItem(Object item) throws Exception {
// Process item and return the result
return null;
}
}
public class MyItemWriter extends AbstractItemWriter {
@Override
public void writeItems(List<Object> items) throws Exception {
// Write the processing results into the target data source
}
}
In the above code, we created a custom STEP, inherited from the ABSTRCTSTEP class, and rewritten the Start method.In the Start method, we set up the Reader, Processor and Writer of Step.Similarly, we can also create custom ITEMREADER, ItemProcessor, and Itemwriter, and implement their Readitem, ProcessItems, and WriteItems methods, respectively.
4. Summary
This article introduces the basic concepts and main components of the JSR 352 API framework, and provides a simple guideline.Using JSR 352, developers can more conveniently write and manage batch processing applications and improve development efficiency.I hope this article will be helpful for you to understand JSR 352.
