使用 JdbcBatchItemWriter 编写项目列表 [英] Writing List of Items using JdbcBatchItemWriter

问题描述

目前我正在使用 JpaItemWriter 编写对象列表，如下所示，工作正常.现在由于性能问题，我想将 JpaItemWriter 更改为 JdbcBatchItemWriter.

Currently i am using JpaItemWriter to write the list of objects as below which is working fine. Now i want to change the JpaItemWriter to JdbcBatchItemWriter due to performance issue.

    public class MyItemWriter implements ItemWriter<List<MyDomainObject>> {

    @Override  
    public void write(List<? extends Lists<MyDomainObject>> items) {
    JpaItemWriter<MyDomainObject> writer = new JpaItemWriter<>();    
    for(List<MyDomainObject> o : items)
        {
          writer.write(o);
        }
      }
    }

建议使用 JdbcBatchItemWriter 编写对象列表的示例片段将有所帮助.尝试使用 ItemSqlParameterSourceProvider 它并没有帮助结束 org.springframework.dao.InvalidDataAccessApiUsageException: No value provided for the SQL parameter 异常

Suggest a sample snippets which uses the JdbcBatchItemWriter to write the List of objects will helps. Tried using the ItemSqlParameterSourceProvider it did't help ending up in org.springframework.dao.InvalidDataAccessApiUsageException: No value supplied for the SQL parameter exception

推荐答案

你的例子不正确.您正在 write 方法中创建一个 JpaItemWriter，因此每次调用 write 时都会创建一个新实例.这可能是导致您出现性能问题的原因.

You example is not correct. You are creating a JpaItemWriter in the write method, so a new instance is created on each call to write. This is probably the cause of your performance issue.

更重要的是，委托编写者的生命周期方法(打开/更新/关闭)将不会被尊重(对于没有实现 ItemStream 的 JpaItemWriter 则不是这种情况但如果委托是项目流，这将是一个问题).你的 MyItemWriter 实现应该是这样的:

More importantly, lifecycle methods of the delegate writer (open/update/close) will not be honored (it is not the case for JpaItemWriter which does not implement ItemStream but this would be a problem if the delegate is an item stream). Your MyItemWriter implementation should be something like:

public class MyItemWriter implements ItemWriter<List<MyDomainObject>> {

   private JpaItemWriter jpaItemWriter;

   public MyItemWriter(JpaItemWriter jpaItemWriter) {
      this. jpaItemWriter = jpaItemWriter;
   }

   @Override  
   public void write(List<? extends Lists<MyDomainObject>> items) {  
     for(List<MyDomainObject> o : items) {
       this. jpaItemWriter.write(o);
     }
   }
}

现在，如果您想使用 JdbcBatchItemWriter 编写列表列表，请参阅 Spring Batch - 使用带有列表列表的 ItemWriter.

Now if you want to use the JdbcBatchItemWriter to write a list of lists, see Spring Batch - Using an ItemWriter with List of Lists.

添加了如何根据评论中的要求设置委托的示例代码:

Added a sample code of how to set the delegate as requested in comments:

@Bean
public ListUnpackingItemWriter<T> itemWriter() {
    JdbcBatchItemWriter<T> jdbcBatchItemWriter = null; // configure your jdbcBatchItemWriter
    ListUnpackingItemWriter<T> listUnpackingItemWriter = new ListUnpackingItemWriter<>();
    listUnpackingItemWriter.setDelegate(jdbcBatchItemWriter);
    return listUnpackingItemWriter;
}

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