谁调用类AbstractItemCountingItemStreamItemReader的doopen函数

Question

我知道spring批处理框架何时调用JdbcCursorItemReader的read函数，但在此之前，它首先应该调用doopen函数，spring batch框架在哪里调用doopen函数？

@Bean
 public JdbcCursorItemReader<User> reader(){
  JdbcCursorItemReader<User> reader = new JdbcCursorItemReader<User>();
  reader.setDataSource(dataSource);
  reader.setSql("SELECT id,name FROM user");
  reader.setRowMapper(new UserRowMapper());

  return reader;
 }

 @Bean
 public Step step1() {
  return stepBuilderFactory.get("step1").<User, User> chunk(10)
.reader(reader())
.processor(processor())
.writer(writer())
.build();
 }