使用XmlIo在Apache Beam中读取xml文件 [英] Reading an xml file in apache beam using XmlIo

问题描述

问题陈述：
i正在尝试使用直接运行器
在Beam中读取和打印xml文件的内容，这是代码段：

problem statement: i am trying to read and print contents of an xml file in beam using direct runner here is the code snippet:

 public  class  BookStore{

 public  static  void  main  (string  args[]){

 BookOptions options = PipelineOptionsFactory.fromArgs(args).withValidation().as(BookOptions .class); 

 Pipeline pipeline = Pipeline.create(options);

 PCollection<Book> output = pipeline.apply(XmlIO.<Book>read().from("sample.xml")
                 .withRootElement("book") 
                 .withRecordElement("name")
                 .withRecordClass(Book.class));  

         output.apply(ParDo.of(new DoFn<Book,String>(){
             @ProcessElement 
             public void processElement(ProcessContext c)
             {
                 System.out.println("xml  data "+c.element().getname());    
             }
          }));
 pipeline.run();
}
}

我的pojo类：

@XmlRootElement(name = "book")
@XmlType(propOrder = {"name"})
public class Book{

    private String name;
    @XmlElement(name = "name")
    public String getName ()
    {
    return name;
    }

    public void setName (String name)
    {
    this.name = name;
    }

    @Override
    public String toString()
    {
    return "ClassPojo [name= "+name+"]";
    }

}

我的sample.xml文件

my sample.xml file

<?xml version="1.0" encoding="UTF-8"?> 
<book>
   <name>Harrypotter</name>
</book>

当我使用直接运行程序执行上述代码时，我得到的名称输出为空

when i execute the above code using direct runner i am getting output of "name" as null

有人可以指导我吗？

有没有我可以参考的例子……？

is there any example i can refer into....?

推荐答案

您的XML文件与您在其中定义的 XmlIO 选项不对应您的管道-您需要具有一个包含记录（书）的根元素。解决方案之一可能是这样的：

Your XML file doesn't correspond to XmlIO options that you define in your pipeline - you need to have a root element that includes your records (books). One of the solutions could be something like this:

PCollection<Book> output = pipeline.apply(
        XmlIO.<Book>read().from("sample.xml")
            .withRootElement("books")
            .withRecordElement("book")
            .withRecordClass(Book.class));

，XML文件应如下所示：

and XML file should look like this:

<?xml version="1.0" encoding="UTF-8"?>
<books>
    <book>
        <name>Harrypotter</name>
    </book>
</books>

这篇关于使用XmlIo在Apache Beam中读取xml文件的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！