java - 在 .xml 文件顶部写入注释？

Question

我目前正在编写一个写入 .xml 文件的程序。我想在文件顶部(第一行)放置一条注释，说明更改代码将如何搞乱它。使用 XMLEncoder 可以实现这一点吗？

这是我的代码:

private static void serializeToXML(ArrayList<Item> list)
    { 
        try
        {
            XMLEncoder encoder = new XMLEncoder(new BufferedOutputStream(
                    new FileOutputStream(getSaveLocation())));
            encoder.writeObject(list);
            encoder.close();

        } catch (FileNotFoundException e)
        {
            System.err.println("Error writing list to XML File.");
        } 
    }

谢谢!

Answer 1

首先，在<?xml ... ?>之前不能有任何东西。 .

我想以下 xml 应该是您可能想要的:

<?xml version='1.0' encoding='UTF-8'?>
<!--Some insightful commentary here-->
<SomePojo>
    <id>1</id>
    <name>pojo1</name>
</SomePojo>

您可以尝试 jackson-dataformat-xml。

测试代码

import java.io.StringWriter;

import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLOutputFactory;
import javax.xml.stream.XMLStreamWriter;

import com.fasterxml.jackson.dataformat.xml.XmlMapper;

import org.testng.annotations.Test;

public class XMLWriteCommentTest {

@Test
public void test() throws Exception {
    // First create Stax components we need
    XMLInputFactory  xmlInputFactory = XMLInputFactory.newFactory();
    XMLOutputFactory xmlOutputFactory = XMLOutputFactory.newFactory();
    StringWriter out = new StringWriter();
    XMLStreamWriter sw = xmlOutputFactory.createXMLStreamWriter(out);

    // then Jackson components
    XmlMapper mapper = new XmlMapper(xmlInputFactory);

    sw.writeStartDocument();
    // comment
    sw.writeComment("Some insightful commentary here");
    // Write whatever content POJOs...
    mapper.writeValue(sw, new SomePojo("1", "pojo1"));

    sw.writeEndDocument();
    // getResult
    String xml = out.toString();
    System.out.println(xml);
    }
}    
class SomePojo {
    private String id;
    private String name;

    public SomePojo(String id, String name){
        this.id = id;
        this.name = name;
    }

    public String getId(){
        return this.id;
    }

    public void setId(String id){
        this.id = id;
    }

    public String getName(){
        return this.name;
    }

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

Maven 依赖

<dependency>
<groupId>com.fasterxml.jackson.dataformat</groupId>
<artifactId>jackson-dataformat-xml</artifactId>
<version>2.10.1</version>
</dependency>