Java Reference
In-Depth Information
Listing 4-50. Basic Retry Configuration
<job id="flowJob">
<step id="retryStep">
<chunk reader="itemReader" writer="itemWriter"
processor="itemProcessor" commit-interval="20"
In the flowJob 's retryStep , when a RemoteAccessException is thrown by any of the components in
the step ( itemReader , itemWriter , or itemProcessor ) the item is retried up to three times before the step
Another way to add retry logic to your batch job is to do it yourself via
org.springframework.batch.retry.RetryTemplate . Like most other templates provided in Spring, this
one simplifies the development of retry logic by providing a simple API to encapsulate the retryable logic
in a method that is then managed by Spring. In the case of RetryTemplate , you need to develop two
pieces: the org.springframework.batch.retry.RetryPolicy interface and the
org.springframework.batch.retry.RetryCallback interface. RetryPolicy allows you to define under
what conditions an item's processing is to be retried. Spring provides a number of implementations,
including ones for retrying based on an exception being thrown (which you used by default in Listing 4-
50), timeout, and others. The other piece of coding retry logic is the use of the RetryCallback interface.
This interface provides a single method, doWithRetry(RetryContext context) , that encapsulates the
logic to be retried. When you use RetryTemplate , if an item is to be retried, the doWithRetry method is
called as long as RetryPolicy specifies it to be. Let's look at an example.
Listing 4-51 shows the code to retry a call to a database with a timeout policy of 30 seconds. This
means it will continue to try executing the database call until it works or until 30 seconds has passed.
Listing 4-51. Using RetryTemplate and RetryCallback
package com.apress.springbatch.chapter4;
import java.util.List;
import org.springframework.batch.item.ItemWriter;
import org.springframework.batch.retry.RetryCallback;
import org.springframework.batch.retry.RetryContext;
public class RetryItemWriter implements ItemWriter<Customer> {
private CustomerDAO customerDao;
private RetryTemplate retryTemplate;
public void write(List<? extends Customer> customers) throws Exception {
Search WWH ::

Custom Search