一：执行上下文

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1.1 Job Context 作业上下文

JobContext 绑定 JobExecution 执行对象，为Job作业执行提供执行环境(上下文)。

1.2 Step Context 步骤上下文

StepContext 绑定 StepExecution 执行对象，为Step步骤执行提供执行环境(上下文)。

1.3 ExecutionContext 执行上下文

Job ExecutionContext：一次作业运行，所有Step步骤间数据共享。
Step ExecutionContext：一次步骤运行，单个Step步骤间(ItemReader/ItemProcessor/ItemWrite组件间)数据共享。

1.4 作业线

作业线： Job---JobInstance---JobContext---JobExecution--ExecutionContext
步骤线： Step--StepContext --StepExecution--ExecutionContext

1.5 作业上下文API JobSynchronizationManager

JobContext context = JobSynchronizationManager.getContext();
JobExecution jobExecution = context.getJobExecution();
Map<String, Object> jobExecutionContext = context.getJobExecutionContext();
Map<String, Object> jobParameters1 = context.getJobParameters();

1.6 步骤上下文API

StepContext stepContext = chunkContext.getStepContext();
StepExecution stepExecution = stepContext.getStepExecution();
Map<String, Object> stepExecutionContext = stepContext.getStepExecutionContext();
Map<String, Object> jobExecutionContext = stepContext.getJobExecutionContext();
ExecutionContext executionContext = stepExecution.getExecutionContext();
executionContext.put("key", "value");

JobExecution jobExecution = stepExecution.getJobExecution();
ExecutionContext executionContext1 = jobExecution.getExecutionContext();
executionContext1.put("key2", "value2");

1.7上下文案例

@Bean
@StepScope
public Tasklet hellWorldTasklet(@Value("#{jobParameters['timestamp']}") Long timestamp) {
    return new Tasklet() {
        @Override
        public RepeatStatus execute(StepContribution stepContribution, ChunkContext chunkContext) throws Exception {
            // 步骤上下文
            ExecutionContext stepExeCtx = chunkContext.getStepContext().getStepExecution().getExecutionContext();
            stepExeCtx.put("step-context-key1", "value1");

            // 作业上下文
            ExecutionContext jobExeCtx = chunkContext.getStepContext().getStepExecution().getJobExecution().getExecutionContext();
            jobExeCtx.put("job-context-key1", "value1");
            return RepeatStatus.FINISHED;
        }
    };
}

@Bean
public Tasklet hellWorldTasklet2() {
    return new Tasklet() {
        @Override
        public RepeatStatus execute(StepContribution stepContribution, ChunkContext chunkContext) throws Exception {
            // 步骤上下文（步骤上下文在步骤里面相当于是局部变量，在其它Step中获取不到）
            ExecutionContext stepExeCtx = chunkContext.getStepContext().getStepExecution().getExecutionContext();
            // null(作业上下文不是用来作业之间共享数据的，而是用来ItemReader、ItemProcessor、ItemWriter之间共享数据的，所以取不到)
            Object stepCtxValue = stepExeCtx.get("step-context-key1");

            // 作业上下文(用来步骤之间共享数据的，所以步骤2能获取到步骤1的数据)
            ExecutionContext jobExeCtx = chunkContext.getStepContext().getStepExecution().getJobExecution().getExecutionContext();
            // value1
            Object JobCtxValue = jobExeCtx.get("job-context-key1");
            return RepeatStatus.FINISHED;
        }
    };
}

BATCH_JOB_EXECUTION_CONTEXT
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BATCH_STEP_EXECUTION_CONTEXT

二：单步骤重启继续运行

该示例是模拟的当一个步骤发生错误时，当修复好错误时，会接上次错误处继续执行，而不是从第一个步骤完重新开始。

@Configuration
public class ErrorJobConfig {
    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;



    @Bean
    public Job errorJob() {
        return jobBuilderFactory.get("errorJob")
                .start(step1())
                .next(step2())
                .build();
    }

    @Bean
    public Step step1() {
        return stepBuilderFactory.get("step1")
                .tasklet(new Tasklet() {
                    @Override
                    public RepeatStatus execute(StepContribution contribution, ChunkContext chunkContext) throws Exception {
                        ExecutionContext executionContext = chunkContext.getStepContext().getStepExecution().getExecutionContext();
                        if (!executionContext.containsKey("mock")) {
                            executionContext.put("mock", "value");
                            System.err.println("step1模拟发生异常");
                            throw new RuntimeException("step1模拟发生异常");
                        }
                        System.err.println("step1 execute finish");
                        return RepeatStatus.FINISHED;
                    }
                })
                .build();
    }

    @Bean
    public Step step2() {
        return stepBuilderFactory.get("step2")
                .tasklet(new Tasklet() {
                    @Override
                    public RepeatStatus execute(StepContribution contribution, ChunkContext chunkContext) throws Exception {
                        ExecutionContext executionContext = chunkContext.getStepContext().getStepExecution().getExecutionContext();
                        if (!executionContext.containsKey("mock")) {
                            executionContext.put("mock", "value");
                            System.err.println("step2模拟发生异常");
                            throw new RuntimeException("step2模拟发生异常");
                        }
                        System.err.println("step2 execute finish");
                        return RepeatStatus.FINISHED;
                    }
                })
                .build();
    }
}

@RequestMapping("/start")
public ExitStatus start() throws Exception {
    JobExecution jobExecution = jobLauncher.run(errorJob, new JobParameters());
    return jobExecution.getExitStatus();
}