问题
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();
}
}
my pojo class:
@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+"]";
}
}
my sample.xml file
<?xml version="1.0" encoding="UTF-8"?>
<book>
<name>Harrypotter</name>
</book>
when i execute the above code using direct runner i am getting output of "name" as null
can somebody guide me on this.
is there any example i can refer into....?
回答1:
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));
and XML file should look like this:
<?xml version="1.0" encoding="UTF-8"?>
<books>
<book>
<name>Harrypotter</name>
</book>
</books>
来源：https://stackoverflow.com/questions/61822778/reading-an-xml-file-in-apache-beam-using-xmlio