以声明方式将 JavaObject 映射到 Javabean

Question

Edit1

I am not sure if the title is best for the problem so if any have some more orinted title please suggest

i am trying my hands on camel where i have to fetch some csv file from a file system and needs to convert it to xml format and place it on some other system

i am using camel for this and here is my sample POC code

import org.apache.camel.CamelContext;

import org.apache.camel.Exchange;

import org.apache.camel.Message;

import org.apache.camel.Processor;

import org.apache.camel.builder.RouteBuilder;

import org.apache.camel.impl.DefaultCamelContext;
import com.poc.convertor.CSVConverterBean;

  public class TestPOC {

           public static void main(String args[]) throws Exception {
           CamelContext context = new DefaultCamelContext();
           context.addRoutes(new RouteBuilder() {

                  public void configure() {
                          from("file:data/csv?noop=true").unmarshal().csv().bean(new CSVConverterBean(),"processCSVInvoice").to("file:data/csvoutput?fileName=test.xml").marshal("jaxb");


                  }

              });
               context.start();
               Thread.sleep(1000);
               context.stop();
          }

}

In this approach camel csv unmarshaller will covert the csv file in to java list List<List<String>> i have written a java converter CSVConverterBean which will iterate the list and set the values in the respective java objects being generated by jaxb 2.x, final object is being marshaled in to xml and file is being saved.

Everything is being working properly with only one issue, if in future there arises any request to change mapping we need to do the modification in CSVConverterBean and than this java file needs to be recompiled and need to be redistributed which we want to avoid.

my question is, Is there any way by which we can map the values from the java List being given by Camel to the respective java classes being generated by the JaxB so that the need to recompile java code can be avooided.

Answer 1

You can provide a "from-to" kind of configuration file to map the columns of your CSV data with your Bean properties, and code an algorithm to read that file and process the convertion.

You could do with a.properties file:

# mapping.properties
column0=propertyOne
column1=propertyTwo

For each column in your CSV, you get the value from the property file and find which property you should set the value on.

int columnIndex = 0;
for(String column : csvColumns) {
    String property = findProperty(columnIndex);
    reflectionUtil.setValue(object, property, column);
    columnIndex++;
}

This may give you some hint.

Whenever your data changes, you will only need to change the property file, not the class.

Answer 2

Use Bruno's idea, but read the property names from the header row in the csv file.

Answer 3

I have solved this problem using dom4j.camel gave me back csv as list> and firstly i read the headers and than made these headers and the XML tags and the values as there respected values on run time.