问题
I have a requirement where I am reading from the database in two different Query. Each Query has its own SQL. The SQLs are similar and are going after the same set of tables for the most part, with minor differences. I wanted to check if I can have two SQLs in an ItemReader or maybe using a jdbctemplate is possible?
Any ideas, sample code?
回答1:
in the event that you want to 're-use' an existing JdbcCursorItemReader (or one of the other Spring Batch Jdbc*ItemReaders), you can switch the SQL dynamically by leveraging the step scope. Below is an example of a configuration that switches the SQL based on the sqlKey property from the JobParameters. the source of the statements is a simple map.
<?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:util="http://www.springframework.org/schema/util"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd
http://www.springframework.org/schema/batch http://www.springframework.org/schema/batch/spring-batch.xsd">
<batch:job id="switchSQL">
<batch:step id="switchSQL.step1">
<batch:tasklet>
<batch:chunk reader="sqlItemReader" writer="outItemWriter" commit-interval="10"/>
</batch:tasklet>
</batch:step>
</batch:job>
<bean id="sqlItemReader"
class="org.springframework.batch.item.database.JdbcCursorItemReader" scope="step">
<property name="dataSource" ref="dataSource"/>
<property name="sql" value="#{@sqlStatements[jobParameters['sqlKey']]}"/>
<property name="rowMapper">
<bean class="de.incompleteco.spring.batch.data.ColumnRowMapper"/>
</property>
</bean>
<util:map id="sqlStatements">
<entry key="sql1" value="select * from table_one"/>
<entry key="sql2" value="select * from table_two"/>
</util:map>
<bean id="outItemWriter"
class="org.springframework.batch.item.adapter.ItemWriterAdapter">
<property name="targetObject" ref="outWriter"/>
<property name="targetMethod" value="write"/>
</bean>
<bean id="outWriter" class="de.incompleteco.spring.batch.item.SystemOutItemWriter"/>
</beans>
here are the supporting classes;
(a simple itemwriter)
package de.incompleteco.spring.batch.item;
public class SystemOutItemWriter {
public void write(Object object) {
System.out.println(object);
}
}
(and a simple rowmapper)
package de.incompleteco.spring.batch.data;
import java.sql.ResultSet;
import java.sql.SQLException;
import org.springframework.jdbc.core.RowMapper;
public class ColumnRowMapper implements RowMapper<String> {
public String mapRow(ResultSet rs, int rowNum) throws SQLException {
return rs.getString(1);
}
}
and here's the remaining config
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="jobRepository"
class="org.springframework.batch.core.repository.support.MapJobRepositoryFactoryBean"/>
<bean id="jobExplorer"
class="org.springframework.batch.core.explore.support.MapJobExplorerFactoryBean">
<property name="repositoryFactory" ref="&jobRepository"/>
</bean>
<bean id="jobLauncher"
class="org.springframework.batch.core.launch.support.SimpleJobLauncher">
<property name="jobRepository" ref="jobRepository"/>
</bean>
<bean id="transactionManager"
class="org.springframework.batch.support.transaction.ResourcelessTransactionManager">
</bean>
<bean class="org.springframework.batch.core.scope.StepScope"/>
</beans>
and
<?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: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/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc.xsd">
<jdbc:embedded-database id="dataSource" type="H2">
<jdbc:script location="classpath:/META-INF/sql/schema-h2.sql"/>
<jdbc:script location="classpath:/META-INF/sql/insert-h2.sql"/>
</jdbc:embedded-database>
<bean id="dataSourceTransactionManager"
class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"/>
</bean>
</beans>
and the sql stuff
create table table_one (
column_a varchar(50)
);
create table table_two (
column_a varchar(50)
);
--table one
insert into table_one (column_a) values ('hello');
insert into table_one (column_a) values ('world');
--table two
insert into table_two (column_a) values ('hey');
now finally a unit test
package de.incompleteco.spring;
import static org.junit.Assert.assertFalse;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.batch.core.Job;
import org.springframework.batch.core.JobExecution;
import org.springframework.batch.core.JobParameters;
import org.springframework.batch.core.JobParametersBuilder;
import org.springframework.batch.core.explore.JobExplorer;
import org.springframework.batch.core.launch.JobLauncher;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration({"classpath:/META-INF/spring/*-context.xml"})
public class SwitchSQLIntegrationTest {
@Autowired
private Job job;
@Autowired
private JobLauncher jobLauncher;
@Autowired
private JobExplorer jobExplorer;
@Test
public void test() throws Exception {
//setup the parameters
JobParameters parameters = new JobParametersBuilder().addLong("runtime",System.currentTimeMillis())
.addString("sqlKey", "sql1").toJobParameters();
//run
JobExecution execution = jobLauncher.run(job,parameters);
//test
while (jobExplorer.getJobExecution(execution.getId()).isRunning()) {
Thread.sleep(100);
}//end while
//load
execution = jobExplorer.getJobExecution(execution.getId());
//test
assertFalse(execution.getStatus().isUnsuccessful());
//run it again
parameters = new JobParametersBuilder().addLong("runtime",System.currentTimeMillis())
.addString("sqlKey", "sql2").toJobParameters();
//run
execution = jobLauncher.run(job,parameters);
//test
while (jobExplorer.getJobExecution(execution.getId()).isRunning()) {
Thread.sleep(100);
}//end while
//load
execution = jobExplorer.getJobExecution(execution.getId());
//test
assertFalse(execution.getStatus().isUnsuccessful());
}
}
来源：https://stackoverflow.com/questions/17277664/one-itemreader-2-sql-query-jdbctemplate