[英]Spring Batch JdbcPagingItemReader seems not EXECUTING ALL THE ITEMS
[英]Spring Batch - My Batch seems executing two steps at the same time?
我真的不明白發生了什么。 我正在研究 Spring Batch,由於某些原因,我想一個接一個地執行兩個步驟。
現在請不要介意這些步驟當前在做什么,只要記住我想按順序執行兩個步驟。
這是代碼:
@Configuration
@EnableBatchProcessing
public class JobConfiguration {
@Autowired
private JobBuilderFactory jobBuilderFactory;
@Autowired
private StepBuilderFactory stepBuilderFactory;
private List<Employee> employeesToSave = new ArrayList<Employee>();
public JsonItemReader<Employee> jsonReader() {
System.out.println("Try to read JSON");
final ObjectMapper mapper = new ObjectMapper();
final JacksonJsonObjectReader<Employee> jsonObjectReader = new JacksonJsonObjectReader<>(
Employee.class);
jsonObjectReader.setMapper(mapper);
return new JsonItemReaderBuilder<Employee>().jsonObjectReader(jsonObjectReader)
.resource(new ClassPathResource("input.json"))
.name("myReader")
.build();
}
public ListItemReader<Employee> listReader() {
System.out.println("Read from list");
return new ListItemReader<Employee>(employeesToSave);
*/
}
public ItemProcessor<Employee,Employee> filterProcessor() {
return employee -> {
System.out.println("Processing JSON");
return employee;
};
}
public ItemWriter<Employee> filterWriter() {
return listEmployee -> {
employeesToSave.addAll(listEmployee);
System.out.println("Save on list " + listEmployee.toString());
};
}
public ItemWriter<Employee> insertToDBWriter() {
System.out.println("Try to save on DB");
return listEmployee -> {
System.out.println("Save on DB " + listEmployee.toString());
};
}
public Step filterStep() {
StepBuilder stepBuilder = stepBuilderFactory.get("filterStep");
SimpleStepBuilder<Employee, Employee> simpleStepBuilder = stepBuilder.chunk(5);
return simpleStepBuilder.reader(jsonReader()).processor(filterProcessor()).writer(filterWriter()).build();
}
public Step insertToDBStep() {
StepBuilder stepBuilder = stepBuilderFactory.get("insertToDBStep");
SimpleStepBuilder<Employee, Employee> simpleStepBuilder = stepBuilder.chunk(5);
return simpleStepBuilder.reader(listReader()).writer(insertToDBWriter()).build();
}
@Bean
public Job myJob(JobRepository jobRepository, PlatformTransactionManager platformTransactionManager) {
return jobBuilderFactory.get("myJob").incrementer(new RunIdIncrementer())
.start(filterStep())
.next(insertToDBStep())
.build();
}
}
為什么 insertToDBStep 不在 filterStep 的末尾開始,實際上看起來過濾器正在同時運行? 為什么它看起來像在初始化 Root WebApplicationContext 之后開始工作?
這是輸出。
2022-05-23 15:40:49.418 INFO 14008 --- [ restartedMain] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1024 ms
Try to read JSON
Read from list
Try to save on DB
2022-05-23 15:40:49.882 INFO 14008 --- [ restartedMain] o.s.b.d.a.OptionalLiveReloadServer : LiveReload server is running on port 35729
2022-05-23 15:40:49.917 INFO 14008 --- [ restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''
2022-05-23 15:40:49.926 INFO 14008 --- [ restartedMain] c.marco.firstbatch.TestBatchApplication : Started TestBatchApplication in 1.985 seconds (JVM running for 2.789)
2022-05-23 15:40:49.927 INFO 14008 --- [ restartedMain] o.s.b.a.b.JobLauncherApplicationRunner : Running default command line with: []
2022-05-23 15:40:49.928 WARN 14008 --- [ restartedMain] o.s.b.c.c.a.DefaultBatchConfigurer : No datasource was provided...using a Map based JobRepository
2022-05-23 15:40:49.928 WARN 14008 --- [ restartedMain] o.s.b.c.c.a.DefaultBatchConfigurer : No transaction manager was provided, using a ResourcelessTransactionManager
2022-05-23 15:40:49.943 INFO 14008 --- [ restartedMain] o.s.b.c.l.support.SimpleJobLauncher : No TaskExecutor has been set, defaulting to synchronous executor.
2022-05-23 15:40:49.972 INFO 14008 --- [ restartedMain] o.s.b.c.l.support.SimpleJobLauncher : Job: [SimpleJob: [name=myJob]] launched with the following parameters: [{run.id=1}]
2022-05-23 15:40:50.003 INFO 14008 --- [ restartedMain] o.s.batch.core.job.SimpleStepHandler : Executing step: [filterStep]
Processing JSON
Processing JSON
Processing JSON
Processing JSON
Processing JSON
Save on list [com.marco.firstbatch.Employee@958d6e7, com.marco.firstbatch.Employee@464d17f8, com.marco.firstbatch.Employee@705520ac, com.marco.firstbatch.Employee@1a9f8e93, com.marco.firstbatch.Employee@55bf8cc9]
Processing JSON
Processing JSON
Save on list [com.marco.firstbatch.Employee@55d706c0, com.marco.firstbatch.Employee@1bc46dd4]
2022-05-23 15:40:50.074 INFO 14008 --- [ restartedMain] o.s.batch.core.step.AbstractStep : Step: [filterStep] executed in 70ms
2022-05-23 15:40:50.081 INFO 14008 --- [ restartedMain] o.s.batch.core.job.SimpleStepHandler : Executing step: [insertToDBStep]
2022-05-23 15:40:50.084 INFO 14008 --- [ restartedMain] o.s.batch.core.step.AbstractStep : Step: [insertToDBStep] executed in 3ms
2022-05-23 15:40:50.088 INFO 14008 --- [ restartedMain] o.s.b.c.l.support.SimpleJobLauncher : Job: [SimpleJob: [name=myJob]] completed with the following parameters: [{run.id=1}] and the following status: [COMPLETED] in 96ms
提前致謝。
這些步驟按順序正確執行。 您將System.out.println
語句放在兩個“種類”的地方:
在您的情況下,Spring Framework 將調用以下 bean 定義方法來定義第一步filterStep()
:
jsonReader()
:打印Try to read JSON
。 此時不讀取文件,只定義了json reader bean。 更准確的日志消息是: json reader bean created
。listReader()
:打印Read from list
。 同樣在這里,文件讀取還沒有開始。 更准確的日志消息是: list reader bean created
。filterProcessor()
:什么都不打印。 日志語句位於ItemProcessor#process
方法中。 這將在運行時由 Spring Batch 調用,而不是在配置時間的這個時間點filterWriter()
:這里一樣,打印語句在運行時調用的 write 方法中,而不是在配置時調用這導致filterStep()
的以下輸出:
Try to read JSON
Read from list
現在 Spring Framework 開始定義下一步, insertToDBStep()
。 為此,它將根據您的步驟定義按順序調用以下方法:
listReader()
:這個 bean 已經定義了 bean,Spring 將重用相同的實例(默認情況下,Spring bean 是單例)。 因此,此方法沒有輸出。insertToDBWriter()
:打印Try to save on DB
。 同樣在這里,這里沒有實際保存到數據庫。 更准確的日志消息將是insertToDBWriter bean created
(或者更准確地說, attempting to create insertToDBWriter bean
,以防后面的代碼拋出異常)。您現在有以下累積輸出:
Try to read JSON
Read from list
Try to save on DB
至此,Spring Framework 已經完成了配置應用上下文的工作,Spring Batch 接管並啟動了這項工作。 filterStep()
的實際處理開始:
ListItemReader
) 在read
方法中沒有任何輸出。Processing JSON
Save on list ...
您似乎有兩個塊(第一個有 5 個項目,第二個有 2 個項目),這導致以下輸出:
2022-05-23 15:40:50.003 INFO 14008 --- [ restartedMain] o.s.batch.core.job.SimpleStepHandler : Executing step: [filterStep]
Processing JSON
Processing JSON
Processing JSON
Processing JSON
Processing JSON
Save on list [com.marco.firstbatch.Employee@958d6e7, com.marco.firstbatch.Employee@464d17f8, com.marco.firstbatch.Employee@705520ac, com.marco.firstbatch.Employee@1a9f8e93, com.marco.firstbatch.Employee@55bf8cc9]
Processing JSON
Processing JSON
Save on list [com.marco.firstbatch.Employee@55d706c0, com.marco.firstbatch.Employee@1bc46dd4]
2022-05-23 15:40:50.074 INFO 14008 --- [ restartedMain] o.s.batch.core.step.AbstractStep : Step: [filterStep] executed in 70ms
然后,下一步開始執行,您將獲得以下輸出:
2022-05-23 15:40:50.081 INFO 14008 --- [ restartedMain] o.s.batch.core.job.SimpleStepHandler : Executing step: [insertToDBStep]
2022-05-23 15:40:50.084 INFO 14008 --- [ restartedMain] o.s.batch.core.step.AbstractStep : Step: [insertToDBStep] executed in 3ms
在這里,您可能會問為什么insertToDBWriter()
沒有寫入任何項目(即為什么沒有Save on DB ..
日志)。 這是因為listReader()
是一個單例 bean,並且您在兩個步驟中都在使用它,所以當第二步調用它的read
方法時,它仍然會返回null
,因為使用了相同的實例並且已經用盡了步驟 1 中的項目。因此,此步驟立即結束,因為沒有要處理的項目。 如果要在第二步中重新讀取列表中的項目,可以使用@StepScope
注釋 reader 方法。 這將為每個步驟創建一個不同的閱讀器實例。
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