using Spring batch I want to read the data from PostgreSQL DB, for the same I am using Spring-boot. I want to autowired the service inside the custom-reader which implementing the ItemReader but every time I am getting null value.
custom-reader as below-
public class PostgresDatabaseReader implements ItemReader<Employee> {
private int count = 0;
@Autowired
private EmployeeService employeeService;
@Override
public Employee read() throws Exception, UnexpectedInputException, ParseException, NonTransientResourceException {
System.out.println("Postgres Reader is reading the data");
List<Employee> employees = new ArrayList<Employee>();//this.employeeService.findAll();
employees = this.employeeService.findAll();
if (CollectionUtils.isNotEmpty(employees)) {
if (count < employees.size()) {
return employees.get(count++);
} else {
count = 0;
}
} else {
count = 0;
}
return null;
}
}
Configuration as -
@Configuration
@EnableBatchProcessing
@EnableAutoConfiguration
public class BatchConfig {
@Autowired
public JobBuilderFactory jobBuilderFactory;
@Autowired
public StepBuilderFactory stepBuilderFactory;
@Bean
public EmployeeService employeeService() {
return new EmployeeServiceImpl();
}
@Bean
public ItemReader<Employee> postgresDatabaseReader() {
return new PostgresDatabaseReader();
}
....
Service which I need to inject/autowired -
@Service
public class EmployeeServiceImpl implements EmployeeService {
@Autowired
private EmployeeRepository employeeRepository;
@Override
public List<Employee> findAll() {
return this.employeeRepository.findAll();
}
@Override
public Employee save(Employee employee) {
return this.employeeRepository.save(employee);
}
}
Exception as -
2022-03-27 13:12:53.564 ERROR 8740 --- [nio-8080-exec-2] o.s.batch.core.step.AbstractStep : Encountered an error executing step orderStep1 in job processJob
java.lang.NullPointerException: null
at com.javainuse.step.PostgresDatabaseReader.read(PostgresDatabaseReader.java:35) ~[classes/:na]
at com.javainuse.step.PostgresDatabaseReader.read(PostgresDatabaseReader.java:1) ~[classes/:na]
at org.springframework.batch.core.step.item.SimpleChunkProvider.doRead(SimpleChunkProvider.java:91) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.core.step.item.SimpleChunkProvider.read(SimpleChunkProvider.java:157) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.core.step.item.SimpleChunkProvider$1.doInIteration(SimpleChunkProvider.java:116) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.repeat.support.RepeatTemplate.getNextResult(RepeatTemplate.java:374) ~[spring-batch-infrastructure-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.repeat.support.RepeatTemplate.executeInternal(RepeatTemplate.java:215) ~[spring-batch-infrastructure-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.repeat.support.RepeatTemplate.iterate(RepeatTemplate.java:144) ~[spring-batch-infrastructure-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.core.step.item.SimpleChunkProvider.provide(SimpleChunkProvider.java:110) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.core.step.item.ChunkOrientedTasklet.execute(ChunkOrientedTasklet.java:69) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.core.step.tasklet.TaskletStep$ChunkTransactionCallback.doInTransaction(TaskletStep.java:406) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.core.step.tasklet.TaskletStep$ChunkTransactionCallback.doInTransaction(TaskletStep.java:330) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:133) ~[spring-tx-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.batch.core.step.tasklet.TaskletStep$2.doInChunkContext(TaskletStep.java:271) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.core.scope.context.StepContextRepeatCallback.doInIteration(StepContextRepeatCallback.java:81) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.repeat.support.RepeatTemplate.getNextResult(RepeatTemplate.java:374) ~[spring-batch-infrastructure-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.repeat.support.RepeatTemplate.executeInternal(RepeatTemplate.java:215) ~[spring-batch-infrastructure-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.repeat.support.RepeatTemplate.iterate(RepeatTemplate.java:144) ~[spring-batch-infrastructure-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.core.step.tasklet.TaskletStep.doExecute(TaskletStep.java:257) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.core.step.AbstractStep.execute(AbstractStep.java:200) ~[spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.core.job.SimpleStepHandler.handleStep(SimpleStepHandler.java:148) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.core.job.flow.JobFlowExecutor.executeStep(JobFlowExecutor.java:64) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.core.job.flow.support.state.StepState.handle(StepState.java:67) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.core.job.flow.support.SimpleFlow.resume(SimpleFlow.java:169) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.core.job.flow.support.SimpleFlow.start(SimpleFlow.java:144) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.core.job.flow.FlowJob.doExecute(FlowJob.java:134) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.core.job.AbstractJob.execute(AbstractJob.java:306) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.batch.core.launch.support.SimpleJobLauncher$1.run(SimpleJobLauncher.java:135) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.core.task.SyncTaskExecutor.execute(SyncTaskExecutor.java:50) [spring-core-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.batch.core.launch.support.SimpleJobLauncher.run(SimpleJobLauncher.java:128) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_202]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_202]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_202]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_202]
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:333) [spring-aop-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190) [spring-aop-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) [spring-aop-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.batch.core.configuration.annotation.SimpleBatchConfiguration$PassthruAdvice.invoke(SimpleBatchConfiguration.java:127) [spring-batch-core-3.0.7.RELEASE.jar:3.0.7.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) [spring-aop-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213) [spring-aop-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at com.sun.proxy.$Proxy92.run(Unknown Source) [na:na]
at com.javainuse.controller.JobInvokerController.handle(JobInvokerController.java:33) [classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_202]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_202]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_202]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_202]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:220) [spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:134) [spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:116) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:622) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) [spring-webmvc-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) [tomcat-embed-websocket-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) [spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:89) [spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) [spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) [spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:108) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:784) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:802) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1410) [tomcat-embed-core-8.5.6.jar:8.5.6]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.6.jar:8.5.6]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_202]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_202]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.6.jar:8.5.6]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_202]
I tried various scenarios but not worked for me. The below problem is similar to mine, I tried that one but still, it was not useful for me. Link- Spring Boot + Batch : Injected/Autowired beans are null in ItemReader
You need to pass from class constructure
public class PostgresDatabaseReader implements ItemReader<Employee> {
private int count = 0;
private EmployeeService employeeService;
public PostgresDatabaseReader(EmployeeService employeeService) {
this.employeeService = employeeService;
...
}
then, on Step
creation will look like this.
@Autowired
private EmployeeService employeeService;
public Step step(String groupName) {
return stepBuilderFactory.get("Step #1:")
.<String> chunk(1)
.reader(new PostgresDatabaseReader(employeeService))
...
and now you can remove @Bean PostgresDatabaseReader
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