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spring_batch

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====== Spring Batch ====== ===== Execute with Test Resources ===== To execute a Spring Batch programm with test resource using Maven the ''exec.classpathScope'' needs to be set on the ''mvn'' command. mvn exec:java -Dexec.classpathScope="test" ===== Output ===== ==== No Output ==== Sometimes there is nothing to be written as there is no output. A NoopItemWriter can be created like this: <sxh java> public class NoopItemWriter<T> implements ItemWriter<T> { @Override public void write(List<? extends T> items) throws Exception { // nothing to do here } } </sxh> The item writer is added to the launch context file. <code><beans:bean id="itemWriter" class="one.time.util.NoopItemWriter" /></code> ===== Input ===== ==== Declare Comment Lines ==== Depending on the system and file comments may start with very different characters. These can be specified in the item writer (if it is supported by the implementation) like this: <sxh xml> <beans:property name="comments"> <beans:array value-type="java.lang.String"> <beans:value>#</beans:value> <beans:value>;</beans:value> <beans:value>!</beans:value> </beans:array> </beans:property> </sxh> ==== Skipping Empty Lines ==== The default reader implementation does not skip empty lines. There is a reader implementation from Robert Kasanicky where empty lines are treated as comments. The implementation can be found {{::extflatfileitemreader.java|here}}. ==== Skipping First Lines ==== CSV files often start with the column names. Generally these must be skipped when processing the file. If you are using the [[http://docs.spring.io/spring-batch/apidocs/org/springframework/batch/item/file/FlatFileItemReader.html | FlatFileItemReader]] you can just add a property to your itemReader bean like this: <beans:property name="linesToSkip" value="1" /> ==== CSV File Input ==== Reading a delimited file with Spring Batch is a combination of using a file item reader, line mapper and line tokenizer. <sxh xml;title: Example> <beans:bean id="itemReader" class="one.time.util.ExtFlatFileItemReader"> <beans:property name="linesToSkip" value="1" /> <beans:property name="resource" value="${data.location}" /> <beans:property name="lineMapper"> <beans:bean class="org.springframework.batch.item.file.mapping.DefaultLineMapper"> <beans:property name="lineTokenizer"> <beans:bean class="org.springframework.batch.item.file.transform.DelimitedLineTokenizer"> <!-- field delimiter of your csv file --> <beans:property name="delimiter" value="," /> <!-- property names of your bean , the order of the names is important --> <beans:property name="names" value="id,street,housenumber" /> </beans:bean> </beans:property> <beans:property name="fieldSetMapper"> <!-- the fields are mapped to properties of your bean --> <beans:bean class="org.springframework.batch.item.file.mapping.BeanWrapperFieldSetMapper"> <!-- the model your data is mapped to --> <beans:property name="targetType" value="my.model.Location" /> </beans:bean> </beans:property> </beans:bean> </beans:property> </beans:bean> </sxh> ===== Create Jar with Dependencies ===== To embed all dependencies and create an executable jar the pom.xml must be extended by the maven-assenbly-plugin. <sxh xml> <build> <plugins> <plugin> <artifactId>maven-assembly-plugin</artifactId> <configuration> <archive> <manifest> <mainClass> org.springframework.batch.core.launch.support.CommandLineJobRunner </mainClass> </manifest> </archive> <descriptorRefs> <descriptorRef>jar-with-dependencies</descriptorRef> </descriptorRefs> </configuration> </plugin> </plugins> </build> </sxh> Create the jar with executing the following line on the command line mvn clean compile assembly:single Execute the program with java -jar program-jar-with-dependencies.jar launch-context.xml jobid {{tag>devel java}}

spring_batch.1394014381.txt.gz · Last modified: 2014/03/05 10:13 by mihael