Java 如何向现有XML添加新节点

在现有xml中添加新节点时遇到问题。所以我有了创建第一个元素的代码

我在这里设置字段

import java.util.*;
import javax.xml.bind.annotation.*;


@XmlRootElement (name = "books")
class Books { 
    private ArrayList<Book> books;
    public Books(){
        books = new ArrayList<>();
    }

    public void add(Book book){
        books.add(book);
    }

    @XmlElement(name = "book")
    public List<Book> getBooks() {
        return books;
    }
}

@XmlRootElement(name = "Book")
class Book {
    // поля
    @XmlAttribute(name="ganre") 
            String ganre;
    @XmlElement
    String bookName;
    @XmlElement
    String bookAuthor;
    @XmlElement
    int bookId;
    @XmlElement
    int bookYear;
    @XmlElement
    boolean bookAvailable;

    public Book(){

    }

    public Book(String ganre, int bookId, String bookName, String bookAuthor, int bookYear, boolean bookAvailable){ // Конструктор чтобы быстрее создавать новые книги не напрягаясь
        setGanre(ganre);
        setBookId(bookId);
        setBookName(bookName);
        setBookAuthor(bookAuthor);
        setBookYear(bookYear);
        setBookAvailable(bookAvailable);
    }

    String getGanre(){ 
        return this.ganre;
    }

    void setGanre(String ganre){ 
        this.ganre = ganre;
    }

    String getBookName(){
        return this.bookName;
    }

    void setBookName(String bookName){
        this.bookName = bookName;
    }

    String getBookAuthor (){
        return this.bookAuthor ;
    }

    void setBookAuthor (String bookAuthor ){
        this.bookAuthor  = bookAuthor;
    }

    boolean getBookAvailable(){
        return this.bookAvailable;
    }

    void setBookAvailable(boolean bookAvailable){
        this.bookAvailable = bookAvailable;
    }

    int getBookId(){
        return this.bookId;
    }

    void setBookId(int bookId){
        this.bookId = bookId;
    }

    int getBookYear(){
        return this.bookYear;
    }


    void setBookYear(int bookYear){
        this.bookYear = bookYear;
    }
}

因此，我试图使重写现有的文件，并在最后添加一个新的节点，但总是只是重写第一个节点

输入

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<books>
    <book ganre="fantasy">
        <bookName>Tron</bookName>
        <bookAuthor>Brawm</bookAuthor>
        <bookId>7111</bookId>
        <bookYear>15</bookYear>
        <bookAvailable>true</bookAvailable>
    </book>

特隆
布拉姆
7111
15
真的

我以后想看什么

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<books>
    <book ganre="fantasy">
        <bookName>Tron</bookName>
        <bookAuthor>Brawm</bookAuthor>
        <bookId>7111</bookId>
        <bookYear>15</bookYear>
        <bookAvailable>true</bookAvailable>
    </book>
    <book ganre="action">
        <bookName>Corn</bookName>
        <bookAuthor>Down</bookAuthor>
        <bookId>312</bookId>
        <bookYear>23</bookYear>
        <bookAvailable>false</bookAvailable>
    </book>
</books>

特隆
布拉姆
7111
15
真的
玉米
向下
312
23
假的

我认为在您的代码中，您将文件用于只写操作

您需要做的是解组当前内容，添加图书条目并将其重新整理

Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
Books books = (Books) jaxbUnmarshaller.unmarshal(file);
books.add(book);
jaxbMarshaller.marshal(bks,file);

---

Frank。

我认为在您的代码中，您将该文件用于只写操作

您需要做的是解组当前内容，添加图书条目并将其重新整理

Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
Books books = (Books) jaxbUnmarshaller.unmarshal(file);
books.add(book);
jaxbMarshaller.marshal(bks,file);

---

Frank.

要将新书添加到现有文件中，首先必须解组XML：

JAXBContext context = JAXBContext.newInstance( Books.class );
 Unmarshaller unmarshaller = context.createUnmarshaller();
 Books books = (Books) unmarshaller.unmarshal( xmlFile );

在此之后，您必须将新书添加到图书列表中：

List<Book> bookList = books.getBooks();
bookList.add( newBook );

---

要将新书添加到现有文件中，首先必须解组XML：

JAXBContext context = JAXBContext.newInstance( Books.class );
 Unmarshaller unmarshaller = context.createUnmarshaller();
 Books books = (Books) unmarshaller.unmarshal( xmlFile );

在此之后，您必须将新书添加到图书列表中：

List<Book> bookList = books.getBooks();
bookList.add( newBook );

---

添加实际的XML和您想要实现的结果XML将非常有用。另外，我看不到您在哪里阅读和解压现有的XML.added结果以及我要实现的内容。添加实际的XML和您想要实现的结果XML会很有用。此外，我看不到您在哪里阅读和解压现有的XML.added结果以及我要实现的目标。