[英]Spring: Step Scope & Bean Autowiring
我目前正處於一個我似乎無法弄清楚的問題的真正痛苦之中。 我希望這里有人可以提供一些指導。 這一切都圍繞着 StepScope、bean 自動裝配和 bean 創建。
(為簡單起見,我減少了配置 class。)
@Configuration
@EnableBatchProcessing
public class Config {
@Bean
@StepScope
public StepScopeBeanOne stepScopeBeanOne() {
return new StepScopeBeanOne();
}
@Bean
@StepScope
public StepScopeBeanTwo stepScopeBeanTwo () {
return new StepScopeBeanTwo();
}
@Bean
@StepScope
public Processor processor() {
return new Processor();
}
}
public class Processor implements ItemProcessor<Incoming, Outgoing> {
//The two injected step scope beans...
@Autowired
private StepScopeBeanOne stepScopeBeanOne;
@Autowired
private StepScopeBeanTwo stepScopeBeanTwo;
@Override
public Outgoing process(Incoming incoming) {
//do process...
}
public void setStepScopeBeanTwo(StepScopeBeanTwo stepScopeBeanTwo) {
this.stepScopeBeanTwo = stepScopeBeanTwo;
}
public void setStepScopeBeanOne(StepScopeBeanOne stepScopeBeanOne) {
this.stepScopeBeanOne = stepScopeBeanOne;
}
//rest of class...
}
org.springframework.beans.factory.UnsatisfiedDependencyException:創建名稱為“scopedTarget.scopedTarget.Processor”的bean時出錯:通過字段“stepScopeBeanOne”表示不滿足的依賴關系; 嵌套異常是 org.springframework.beans.factory.NoSuchBeanDefinitionException:沒有“StepScopeBeanOne”類型的合格 bean 可用:預計至少有 1 個有資格作為自動裝配候選者的 bean。 依賴注解:{@org.springframework.beans.factory.annotation.Autowired(required=true)}
我相信這與解析處理器 bean 時 bean StepScopeBeanOne 不在 ApplicationContext 中有關。
@Configuration
@EnableBatchProcessing
public class Config {
@Bean
@StepScope
public StepScopeBeanOne stepScopeBeanOne() {
return new StepScopeBeanOne();
}
@Bean
@StepScope
public StepScopeBeanTwo stepScopeBeanTwo () {
return new StepScopeBeanTwo();
}
@Bean
@StepScope
public Processor processor() {
Processor processor = new Processor();
processor.setStepScopeBeanOne(stepScopeBeanOne());
processor.setStepScopeBeanTwo(stepScopeBeanTwo());
return processor;
}
}
org.springframework.beans.factory.BeanCreationException:在 class 路徑資源 [Config.class] 中定義名稱為“scopedTarget.scopedTarget.Processor”的 bean 創建錯誤:通過工廠方法進行 Bean 實例化失敗; 嵌套異常是 org.springframework.beans.BeanInstantiationException:無法實例化 [Processor]:工廠方法“處理器”拋出異常; 嵌套異常是 java.lang.IllegalStateException:@Bean 方法 Config.stepScopeBeanOne 被稱為類型 [StepScopeBeanOne] 的 bean 引用,但被類型 [com.sun.proxy.$Proxy149] 的不兼容 bean 實例覆蓋。 在 class 路徑資源 [Config.class] 中定義的 BeanDefinition 中聲明的同名覆蓋 bean
我之前遇到過這個問題,我的解決方法是為我注入的類創建一個接口。
public interface StepScopeBeanOne {
//methods
}
public class StepScopeBeanOneImpl implements StepScopeBeanOne {
//methods
}
我不想再次使用 go 這條路線,因為我相信它會增加代碼的復雜性。 如果有人有不同的解決方案,請分享。
從這些 bean 中刪除步驟 Scope 會導致精細而漂亮的自動裝配。
@Configuration
@EnableBatchProcessing
public class Config {
@Bean
public StepScopeBeanOne stepScopeBeanOne() {
return new StepScopeBeanOne();
}
@Bean
public StepScopeBeanTwo stepScopeBeanTwo () {
return new StepScopeBeanTwo();
}
@Bean
public Processor processor() {
Processor processor = new Processor();
return processor;
}
}
Beans 是通過 @Autowireing 注解注入的。
您可能會問自己,為什么不直接刪除 @StepScope? 好吧,我不能。 我需要在每個這些 bean 上執行 scope 步驟,以允許正確注入 JobParameters。 我們在作業參數中使用步驟名稱來提供微調的步驟配置。
我的目標是讓配置一工作。 在該目標之外,將不勝感激更好地理解 Spring 中的 bean 創建。
我的目標是讓配置一工作。
下面是一個基於“配置一”的完整示例:
import java.util.Arrays;
import org.springframework.batch.core.Job;
import org.springframework.batch.core.JobParameters;
import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepScope;
import org.springframework.batch.core.launch.JobLauncher;
import org.springframework.batch.item.ItemProcessor;
import org.springframework.batch.item.support.ListItemReader;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
@EnableBatchProcessing
public class MyJobConfiguration {
@Bean
@StepScope
public StepScopeBeanOne stepScopeBeanOne() {
return new StepScopeBeanOne();
}
@Bean
@StepScope
public StepScopeBeanTwo stepScopeBeanTwo () {
return new StepScopeBeanTwo();
}
@Bean
@StepScope
public Processor processor() {
return new Processor();
}
@Bean
public Job job(JobBuilderFactory jobs, StepBuilderFactory steps) {
return jobs.get("job")
.start(steps.get("step")
.<Integer, Integer>chunk(5)
.reader(new ListItemReader<>(Arrays.asList(0, 1, 2, 3, 4, 5, 6, 7, 8, 9)))
.processor(processor())
.writer(items -> items.forEach(System.out::println))
.build())
.build();
}
public static void main(String[] args) throws Exception {
ApplicationContext context = new AnnotationConfigApplicationContext(MyJobConfiguration.class);
JobLauncher jobLauncher = context.getBean(JobLauncher.class);
Job job = context.getBean(Job.class);
jobLauncher.run(job, new JobParameters());
}
static class StepScopeBeanOne {
}
static class StepScopeBeanTwo {
}
static class Processor implements ItemProcessor<Integer, Integer> {
@Autowired
private StepScopeBeanOne stepScopeBeanOne;
@Autowired
private StepScopeBeanTwo stepScopeBeanTwo;
@Override
public Integer process(Integer item) throws Exception {
return item + 1;
}
public void setStepScopeBeanOne(StepScopeBeanOne stepScopeBeanOne) {
this.stepScopeBeanOne = stepScopeBeanOne;
}
public void setStepScopeBeanTwo(StepScopeBeanTwo stepScopeBeanTwo) {
this.stepScopeBeanTwo = stepScopeBeanTwo;
}
}
}
這將打印以下 output ,而不會出現關於步進范圍 bean 或依賴注入的任何問題:
[main] WARN org.springframework.batch.core.configuration.annotation.DefaultBatchConfigurer - No datasource was provided...using a Map based JobRepository
[main] WARN org.springframework.batch.core.configuration.annotation.DefaultBatchConfigurer - No transaction manager was provided, using a ResourcelessTransactionManager
[main] INFO org.springframework.batch.core.launch.support.SimpleJobLauncher - No TaskExecutor has been set, defaulting to synchronous executor.
[main] INFO org.springframework.batch.core.launch.support.SimpleJobLauncher - Job: [SimpleJob: [name=job]] launched with the following parameters: [{}]
[main] INFO org.springframework.batch.core.job.SimpleStepHandler - Executing step: [step]
1
2
3
4
5
6
7
8
9
10
[main] INFO org.springframework.batch.core.step.AbstractStep - Step: [step] executed in 73ms
[main] INFO org.springframework.batch.core.launch.support.SimpleJobLauncher - Job: [SimpleJob: [name=job]] completed with the following parameters: [{}] and the following status: [COMPLETED] in 119ms
@StepScope
等價於@Scope(value = "step", proxyMode = ScopedProxyMode.TARGET_CLASS)
(參見javadoc ),因此默認情況下,step-scoped beans 是基於類的代理(使用 cglib)並且不需要實現接口.
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