循环jaxb马歇尔

Question

我只想循环使用相同xml元素但具有不同ID的jaxb marshal，不像我下面的代码解析每个ID的新xml文件并写入旧ID 。

data [] []从矩阵中读入，data [i] [0]表示ID列表，我想将这些id设置为客户ID。

      Customer customer = new Customer();
      File file = new File("C:/data.xml");

      for (int i = 0; i < data.length; i++) {
          customer.setId(data[i][0]);

            JAXBContext jaxbContext = JAXBContext.newInstance(Customer.class);
            Marshaller jaxbMarshaller = jaxbContext.createMarshaller();


            jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

            jaxbMarshaller.marshal(customer, file);
            jaxbMarshaller.marshal(customer, System.out);


      }

上面代码的输出：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<customer id="1"/>
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<customer id="2"/>
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<customer id="3"/>
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<customer id="4"/>
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<customer id="5"/>

我想在一个单独的xml文件中输出所有ID，任何提示？

Answer 1

您可以在Marshaller上设置JAXB_FRAGMENT属性，以防止写出标头。 在编组到另一个文档时，这是必要的。

package forum12925616;

import java.io.*;
import javax.xml.bind.*;

public class Demo {

    private static int X = 5;
    private static int Y = 2;

    public static void main(String[] args) throws Exception {
        int[][] data = new int[X][Y];
        for (int x = 0; x < X; x++) {
            for (int y = 0; y < Y; y++) {
                data[x][y] = x;
            }
        }

        // Create this once
        JAXBContext jaxbContext = JAXBContext.newInstance(Customer.class);
        Marshaller jaxbMarshaller = jaxbContext.createMarshaller();
        jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        jaxbMarshaller.setProperty(Marshaller.JAXB_FRAGMENT, true);

        marshal(jaxbMarshaller, data, System.out);

        FileOutputStream fileOutputStream = new FileOutputStream("src/forum12925616/out.xml");
        marshal(jaxbMarshaller, data, fileOutputStream);
        fileOutputStream.close();
    }

    private static void marshal(Marshaller jaxbMarshaller, int[][] data, OutputStream outputStream) throws Exception {
        OutputStreamWriter writer = new OutputStreamWriter(outputStream);
        writer.write("<?xml version='1.0' encoding='UTF-8' standalone='yes'?>");
        writer.write("\n<customers>\n");
        for (int i = 0; i < data.length; i++) {
            Customer customer = new Customer();
            customer.setId(data[i][0]);
            jaxbMarshaller.marshal(customer, writer);
            writer.write("\n");
        }
        writer.write("<customers>");
        writer.flush();
    }

}

系统和文件输出

下面是控制台和文件的结果输出。

<?xml version='1.0' encoding='UTF-8' standalone='yes'?>
<customers>
<customer id="0"/>
<customer id="1"/>
<customer id="2"/>
<customer id="3"/>
<customer id="4"/>
<customers>

欲获得更多信息

• http://blog.bdoughan.com/2011/08/jaxb-and-java-io-files-streams-readers.html

Answer 2

只需将marhsaller的构造移出循环。 您可以在同一个线程中多次重用marshaller。

或者您是否真的想要将客户列表输出为单个xml文件？ 然后，您需要一个Customer对象数组，然后对阵列进行编组。