Configuring a JobLauncher

Java

当使用 @EnableBatchProcessing 时，会为您提供一个 JobRegistry。本节介绍如何配置您自己的注册器。

When you use @EnableBatchProcessing, a JobRegistry is provided for you. This section describes how to configure your own.

XML

最基本的 JobLauncher 接口的实现是 TaskExecutorJobLauncher。它唯一必需的依赖项是 JobRepository（用于获取执行）。

The most basic implementation of the JobLauncher interface is the TaskExecutorJobLauncher. Its only required dependency is a JobRepository (needed to obtain an execution).

Java

以下示例展示了 Java 中的 TaskExecutorJobLauncher：

The following example shows a TaskExecutorJobLauncher in Java:

Java Configuration
...
@Bean
public JobLauncher jobLauncher() throws Exception {
	TaskExecutorJobLauncher jobLauncher = new TaskExecutorJobLauncher();
	jobLauncher.setJobRepository(jobRepository);
	jobLauncher.afterPropertiesSet();
	return jobLauncher;
}
...
XML

以下示例展示了 XML 中的 TaskExecutorJobLauncher：

The following example shows a TaskExecutorJobLauncher in XML:

XML Configuration
<bean id="jobLauncher"
      class="org.springframework.batch.core.launch.support.TaskExecutorJobLauncher">
    <property name="jobRepository" ref="jobRepository" />
</bean>

获取 JobExecution 后，将其传递给 Job 的执行方法，最终将 JobExecution 返回给调用方，如下图所示：

Once a JobExecution is obtained, it is passed to the execute method of Job, ultimately returning the JobExecution to the caller, as the following image shows:

job launcher sequence sync
Figure 1. Job Launcher Sequence

此顺序比较简单，当从调度器启动时运行良好。但是，当尝试从 HTTP 请求启动时会出现问题。在此场景中，启动需要异步完成，以便 TaskExecutorJobLauncher 立即返回给其调用者。这是因为对于长时间运行的进程（例如批处理作业）所需的时长将 HTTP 请求保持为开启状态并非一项良好的操作。以下图片显示了一个示例顺序：

The sequence is straightforward and works well when launched from a scheduler. However, issues arise when trying to launch from an HTTP request. In this scenario, the launching needs to be done asynchronously so that the TaskExecutorJobLauncher returns immediately to its caller. This is because it is not good practice to keep an HTTP request open for the amount of time needed by long running processes (such as batch jobs). The following image shows an example sequence:

job launcher sequence async
Figure 2. Asynchronous Job Launcher Sequence

您可以通过配置一个 TaskExecutor 来配置 TaskExecutorJobLauncher 以允许这种情况发生。

You can configure the TaskExecutorJobLauncher to allow for this scenario by configuring a TaskExecutor.

Java

以下 Java 示例配置了一个 TaskExecutorJobLauncher 以立即返回：

The following Java example configures a TaskExecutorJobLauncher to return immediately:

Java Configuration
@Bean
public JobLauncher jobLauncher() {
	TaskExecutorJobLauncher jobLauncher = new TaskExecutorJobLauncher();
	jobLauncher.setJobRepository(jobRepository());
	jobLauncher.setTaskExecutor(new SimpleAsyncTaskExecutor());
	jobLauncher.afterPropertiesSet();
	return jobLauncher;
}
XML

以下 XML 示例配置了一个 TaskExecutorJobLauncher 以立即返回：

The following XML example configures a TaskExecutorJobLauncher to return immediately:

XML Configuration
<bean id="jobLauncher"
      class="org.springframework.batch.core.launch.support.TaskExecutorJobLauncher">
    <property name="jobRepository" ref="jobRepository" />
    <property name="taskExecutor">
        <bean class="org.springframework.core.task.SimpleAsyncTaskExecutor" />
    </property>
</bean>

您可以使用 Spring TaskExecutor 接口的任何实现来控制以异步方式对作业执行。

You can use any implementation of the spring TaskExecutor interface to control how jobs are asynchronously executed.