没有可立即使用的组件可以执行您的要求;唯一的解决方案是编写一个ItemReader<>
委托给JdbcCursorItemReader
(或委托给或委托HibernateCursorItemReader
给任何通用ItemReader
实现)的自定义。 您需要准备所有必要的东西(数据源,会话,实际数据库读取器),并将所有委派的读取器绑定到您的自定义读取器。
编辑:您需要使用recussion来模拟一个循环,ItemReader.read()
并在整个作业重新启动期间保留阅读器和委托状态。
class MyItemReader<T> implements ItemReader<T>, ItemStream {
private ItemReader[] delegates;
private int delegateIndex;
private ItemReader<T> currentDelegate;
private ExecutionContext stepExecutionContext;
public void setDelegates(ItemReader[] delegates) {
this.delegates = delegates;
}
@BeforeStep
private void beforeStep(StepExecution stepExecution) {
this.stepExecutionContext = stepExecution.getExecutionContext();
}
public T read() {
T item = null;
if(null != currentDelegate) {
item = currentDelegate.read();
if(null == item) {
((ItemStream)this.currentDelegate).close();
this.currentDelegate = null;
}
}
// Move to next delegate if prevIoUs was exhausted!
if(null == item && this.delegateIndex< this.delegates.length) {
this.currentDelegate = this.delegates[this.currentIndex++];
((ItemStream)this.currentDelegate).open(this.stepExecutionContext);
update(this.stepExecutionContext);
// Recurse to read() to simulate loop through delegates
item = read();
}
return item;
}
public void open(ExecutionContext ctx) {
// During open restore last active reader and restore its state
if(ctx.containsKey("index")) {
this.delegateIndex = ctx.getInt("index");
this.currentDelegate = this.delegates[this.delegateIndex];
((ItemStream)this.currentDelegate ).open(ctx);
}
}
public void update(ExecutionContext ctx) {
// Update current delegate index and state
ctx.putInt("index", this.delegateIndex);
if(null != this.currentDelegate) {
((ItemStream)this.currentDelegate).update(ctx);
}
}
public void close(ExecutionContext ctx) {
if(null != this.currentDelegate) {
((ItemStream)this.currentDelegate).close();
}
}
<bean id="myItemReader" class=path.to.MyItemReader>
<property name="delegates">
<array>
<ref bean="itemReader1"/>
<ref bean="itemReader2"/>
<ref bean="itemReader3"/>
</array>
</property>
</bean>
EDIT2:记住设置属性 ;这是让MyItemReader.read()正常工作所必需的
<bean id="itemReader1" class="JdbcCursorItemReader">
<property name="name" value="itemReader1" />
<!-- Set other properties -->
</bean>