Issue
I want to use a web scraping python script in my batch program but I cannot find any examples in the web for this. Hence, it's possible to use python scripts with the ScriptItemProcessor?
Here's my simple code to test this:
@Bean
public ScriptItemProcessor<Company,Company> scriptItemProcessor() {
return new ScriptItemProcessorBuilder<Company,Company>().language("python").scriptSource("print('hello')").build();
}
UPDATE 1
After adding the required jar the exception changed, so now is recognizing it but the new stack trace is not very descriptive at all.
java.lang.IllegalStateException: Script engine with name 'python' failed to initialize
at org.springframework.scripting.support.StandardScriptUtils.retrieveEngineByName(StandardScriptUtils.java:64) ~[spring-context-5.3.3.jar!/:5.3.3]
at org.springframework.scripting.support.StandardScriptEvaluator.getScriptEngine(StandardScriptEvaluator.java:174) ~[spring-context-5.3.3.jar!/:5.3.3]
at org.springframework.scripting.support.StandardScriptEvaluator.evaluate(StandardScriptEvaluator.java:143) ~[spring-context-5.3.3.jar!/:5.3.3]
at org.springframework.batch.item.support.ScriptItemProcessor.process(ScriptItemProcessor.java:64) ~[spring-batch-infrastructure-4.3.1.jar!/:4.3.1]
at org.springframework.batch.core.step.item.SimpleChunkProcessor.doProcess(SimpleChunkProcessor.java:134) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.batch.core.step.item.SimpleChunkProcessor.transform(SimpleChunkProcessor.java:319) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.batch.core.step.item.SimpleChunkProcessor.process(SimpleChunkProcessor.java:210) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.batch.core.step.item.ChunkOrientedTasklet.execute(ChunkOrientedTasklet.java:77) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.batch.core.step.tasklet.TaskletStep$ChunkTransactionCallback.doInTransaction(TaskletStep.java:407) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.batch.core.step.tasklet.TaskletStep$ChunkTransactionCallback.doInTransaction(TaskletStep.java:331) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:140) ~[spring-tx-5.3.3.jar!/:5.3.3]
at org.springframework.batch.core.step.tasklet.TaskletStep$2.doInChunkContext(TaskletStep.java:273) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.batch.core.scope.context.StepContextRepeatCallback.doInIteration(StepContextRepeatCallback.java:82) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.batch.repeat.support.RepeatTemplate.getNextResult(RepeatTemplate.java:375) ~[spring-batch-infrastructure-4.3.1.jar!/:4.3.1]
at org.springframework.batch.repeat.support.RepeatTemplate.executeInternal(RepeatTemplate.java:215) ~[spring-batch-infrastructure-4.3.1.jar!/:4.3.1]
at org.springframework.batch.repeat.support.RepeatTemplate.iterate(RepeatTemplate.java:145) ~[spring-batch-infrastructure-4.3.1.jar!/:4.3.1]
at org.springframework.batch.core.step.tasklet.TaskletStep.doExecute(TaskletStep.java:258) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.batch.core.step.AbstractStep.execute(AbstractStep.java:208) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.batch.core.job.SimpleStepHandler.handleStep(SimpleStepHandler.java:148) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.batch.core.job.flow.JobFlowExecutor.executeStep(JobFlowExecutor.java:68) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.batch.core.job.flow.support.state.StepState.handle(StepState.java:68) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.batch.core.job.flow.support.SimpleFlow.resume(SimpleFlow.java:169) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.batch.core.job.flow.support.SimpleFlow.start(SimpleFlow.java:144) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.batch.core.job.flow.FlowJob.doExecute(FlowJob.java:137) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.batch.core.job.AbstractJob.execute(AbstractJob.java:320) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.batch.core.launch.support.SimpleJobLauncher$1.run(SimpleJobLauncher.java:147) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.core.task.SyncTaskExecutor.execute(SyncTaskExecutor.java:50) ~[spring-core-5.3.3.jar!/:5.3.3]
at org.springframework.batch.core.launch.support.SimpleJobLauncher.run(SimpleJobLauncher.java:140) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:344) ~[spring-aop-5.3.3.jar!/:5.3.3]
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:198) ~[spring-aop-5.3.3.jar!/:5.3.3]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-5.3.3.jar!/:5.3.3]
at org.springframework.batch.core.configuration.annotation.SimpleBatchConfiguration$PassthruAdvice.invoke(SimpleBatchConfiguration.java:128) ~[spring-batch-core-4.3.1.jar!/:4.3.1]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.3.jar!/:5.3.3]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:215) ~[spring-aop-5.3.3.jar!/:5.3.3]
at com.sun.proxy.$Proxy73.run(Unknown Source) ~[na:na]
at org.springframework.boot.autoconfigure.batch.JobLauncherApplicationRunner.execute(JobLauncherApplicationRunner.java:199) ~[spring-boot-autoconfigure-2.4.2.jar!/:2.4.2]
at org.springframework.boot.autoconfigure.batch.JobLauncherApplicationRunner.executeLocalJobs(JobLauncherApplicationRunner.java:173) ~[spring-boot-autoconfigure-2.4.2.jar!/:2.4.2]
at org.springframework.boot.autoconfigure.batch.JobLauncherApplicationRunner.launchJobFromProperties(JobLauncherApplicationRunner.java:160) ~[spring-boot-autoconfigure-2.4.2.jar!/:2.4.2]
at org.springframework.boot.autoconfigure.batch.JobLauncherApplicationRunner.run(JobLauncherApplicationRunner.java:155) ~[spring-boot-autoconfigure-2.4.2.jar!/:2.4.2]
at org.springframework.boot.autoconfigure.batch.JobLauncherApplicationRunner.run(JobLauncherApplicationRunner.java:150) ~[spring-boot-autoconfigure-2.4.2.jar!/:2.4.2]
at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:795) ~[spring-boot-2.4.2.jar!/:2.4.2]
at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:785) ~[spring-boot-2.4.2.jar!/:2.4.2]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:333) ~[spring-boot-2.4.2.jar!/:2.4.2]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1311) ~[spring-boot-2.4.2.jar!/:2.4.2]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1300) ~[spring-boot-2.4.2.jar!/:2.4.2]
at com.stockanalyzer.stockanalyzer.StockAnalyzerApplication.main(StockAnalyzerApplication.java:136) ~[classes!/:0.0.1-SNAPSHOT]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:49) ~[stock-analyzer-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
at org.springframework.boot.loader.Launcher.launch(Launcher.java:107) ~[stock-analyzer-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
at org.springframework.boot.loader.Launcher.launch(Launcher.java:58) ~[stock-analyzer-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:88) ~[stock-analyzer-0.0.1-SNAPSHOT.jar:0.0.1-SNAPSHOT]
Caused by: java.lang.NullPointerException: null
at org.python.core.PySystemState.<init>(PySystemState.java:214) ~[jython-slim-2.7.2.jar!/:na]
at org.python.util.PythonInterpreter.threadLocalStateInterpreter(PythonInterpreter.java:80) ~[jython-slim-2.7.2.jar!/:na]
at org.python.jsr223.PyScriptEngine.<init>(PyScriptEngine.java:27) ~[jython-slim-2.7.2.jar!/:na]
at org.python.jsr223.PyScriptEngineFactory.getScriptEngine(PyScriptEngineFactory.java:85) ~[jython-slim-2.7.2.jar!/:na]
at org.springframework.scripting.support.StandardScriptUtils.retrieveEngineByName(StandardScriptUtils.java:60) ~[spring-context-5.3.3.jar!/:5.3.3]
... 57 common frames omitted
Final Update
I made it work by adding this dependency in the pom.xml...
<dependency>
<groupId>org.python</groupId>
<artifactId>jython-slim</artifactId>
<version>2.7.2</version>
</dependency>
... and added what's inside the requiresUnpack tag:
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<excludes>
<exclude>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</exclude>
</excludes>
<requiresUnpack>
<dependency>
<groupId>org.python</groupId>
<artifactId>jython-slim</artifactId>
</dependency>
</requiresUnpack>
</configuration>
</plugin>
</plugins>
</build>
PD: remember the item processor needs to be configured in the StepBuilder.
Solution
The ScriptItemProcessor delegates item processing to a org.springframework.scripting.ScriptEvaluator. As of v5.3, Spring Framework provides three implementations of the ScriptEvaluator interface: BshScriptEvaluator, GroovyScriptEvaluator and StandardScriptEvaluator.
By default, if you don't specify which ScriptEvaluator to use, the ScriptItemProcessor will use a StandardScriptEvaluator, see Javadoc of setScriptEvaluator. Now this StandardScriptEvaluator is based on JSR-223 javax.script, so you need to make sure the language you want to use is supported by the default ScriptEngine. In your case, python is not a supported language by default, and hence the error.
If you want to use python through JSR-223, you can use Jython (adding the jar of Jython to the classpath should be enough, see Calling Python from Java through scripting engine (jython)?)
Answered By - Mahmoud Ben Hassine
Answer Checked By - Mildred Charles (JavaFixing Admin)
