In my previous posts under Spring Batch, I explained with example how to use built in out of the box skip policies.
In this post I will explain how to create our own custom skip policy and use it.
To create our own custom skip policy we need to implement the interface org.springframework.batch.core.step.skip.SkipPolicy as shown below
MySkipPolicy
package xml.package25;
import org.springframework.batch.core.step.skip.SkipLimitExceededException;
import org.springframework.batch.core.step.skip.SkipPolicy;
public class MySkipPolicy implements SkipPolicy {
@Override
public boolean shouldSkip(Throwable throwable, int skipCount) throws SkipLimitExceededException {
System.out.println("SkipCount: " + skipCount);
if(skipCount == 5) {
return false;
}
return true;
}
}
In the above code, we implement SkipPolicy interface and provide implementation for shouldSkip method.
The shouldSkip method takes two arguments
1) Throwable –> the exception thrown when processing a record
2) skipCount –> a number representing the number of exception (i.e., argument 1) thrown
The method returns a boolean, if true is returned, the processing continues otherwise the processing stops.
In our code, if the skipCount reaches 5 we are returning false and stopping the processing midway.
Next i will show you how to integrate this skip policy with the batch job.
Below is the xml configuration
<bean id="mySkipPolicy" class="xml.package25.MySkipPolicy"/>
<batch:job id="importEmployees">
<batch:step id="readWriteEmployees">
<batch:tasklet>
<batch:chunk reader="reader" writer="writer" commit-interval="50" skip-policy="mySkipPolicy"/>
</batch:tasklet>
</batch:step>
</batch:job>
In the above xml code, at line 1, I create a bean definition for MySkipPolicy class with id “mySkipPolicy”.
Next I refer this bean at line 6 and set it to attribute “skip-policy”.
In this way we can integrate the custom skip policy with the batch job.
Below is the complete xml configuration for your reference
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:batch="http://www.springframework.org/schema/batch"
xmlns:jdbc="http://www.springframework.org/schema/jdbc"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/batch http://www.springframework.org/schema/batch/spring-batch.xsd
http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.0.xsd">
<bean id="employee" class="xml.package25.Employee" scope="prototype"/>
<bean id="reader" class="org.springframework.batch.item.file.FlatFileItemReader">
<property name="resource" value="file:EmployeeRecordsWithFileParseException.txt"/>
<property name="lineMapper">
<bean class="org.springframework.batch.item.file.mapping.DefaultLineMapper">
<property name="lineTokenizer">
<bean class="org.springframework.batch.item.file.transform.DelimitedLineTokenizer">
<property name="names" value="id,name,status,salary"/>
</bean>
</property>
<property name="fieldSetMapper">
<bean class="org.springframework.batch.item.file.mapping.BeanWrapperFieldSetMapper">
<property name="prototypeBeanName" value="employee"/>
</bean>
</property>
</bean>
</property>
</bean>
<bean id="writer" class="org.springframework.batch.item.file.FlatFileItemWriter">
<property name="resource" value="file:FileOutput.txt"/>
<property name="lineAggregator">
<bean class="org.springframework.batch.item.file.transform.DelimitedLineAggregator">
<property name="fieldExtractor">
<bean class="org.springframework.batch.item.file.transform.BeanWrapperFieldExtractor">
<property name="names" value="id,name,status,salary"/>
</bean>
</property>
</bean>
</property>
</bean>
<bean id="mySkipPolicy" class="xml.package25.MySkipPolicy"/>
<batch:job id="importEmployees">
<batch:step id="readWriteEmployees">
<batch:tasklet>
<batch:chunk reader="reader" writer="writer" commit-interval="50" skip-policy="mySkipPolicy"/>
</batch:tasklet>
</batch:step>
</batch:job>
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"/>
</bean>
<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="org.h2.Driver" />
<property name="url" value="jdbc:h2:file:~/repository" />
<property name="username" value="" />
<property name="password" value="" />
</bean>
<!-- create job-meta tables automatically -->
<jdbc:initialize-database data-source="dataSource">
<jdbc:script
location="org/springframework/batch/core/schema-drop-h2.sql" />
<jdbc:script location="org/springframework/batch/core/schema-h2.sql" />
</jdbc:initialize-database>
<bean id="jobRepository"
class="org.springframework.batch.core.repository.support.JobRepositoryFactoryBean">
<property name="dataSource" ref="dataSource"/>
<property name="transactionManager" ref="transactionManager"/>
<property name="databaseType" value="h2"/>
</bean>
<bean id="jobLauncher" class="org.springframework.batch.core.launch.support.TaskExecutorJobLauncher">
<property name="jobRepository" ref="jobRepository"/>
</bean>
</beans>
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