使用 jaxb (unmarshal) 将 xml 转换为 java 对象

2022-01-19 00:00:00 java jaxb

我有以下 XML，我需要将其转换为 java 对象.

I have the following XML and I need to convert it into a java object.

<tests>
    <test-data> 
         <title>BookTitle</title> 
         <book>BookName</book> 
         <count>64018</count> 
         <test-data> 
            <title>Book title1</title> 
            <book>Book Name1</book> 
            <count>5</count> 
         </test-data> 
         <test-data> 
            <title>Book title2</title> 
            <book>Book Name3</book> 
            <count>5</count> 
         </test-data> 
         <test-data> 
            <title>Book title3</title> 
            <book>Book Name3</book> 
            <count>4</count> 
         </test-data> 
    </test-data>
</tests>

我不确定当我使用 JAXB 转换它时我的 pojo 会是什么.

I am not sure what will be my pojo when I use JAXB to convert it.

根据我的理解，我创建了以下 POJO:

I created the following POJOs as per my understanding:

public class Tests {

    TestData testData;

    public TestData getTestData() {
        return testData;
    }

    public void setTestData(TestData testData) {
        this.testData = testData;
    }
}

public class TestData {
    String title;
    String book;
    String count;

    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public String getBook() {
        return book;
    }
    public void setBook(String book) {
        this.book = book;
    }
    public String getCount() {
        return count;
    }
    public void setCount(String count) {
        this.count = count;
    }
}

请帮助我.提前致谢.

推荐答案

测试

在 Tests 类上，我们将添加一个 @XmlRootElement 注释.这样做会让您的 JAXB 实现知道当一个文档以这个元素开始时，它应该实例化这个类.JAXB 是异常配置，这意味着您只需要在映射与默认值不同的地方添加注释.由于 testData 属性与默认映射不同，我们将使用 @XmlElement 注释.您可能会发现以下教程很有帮助:http://wiki.eclipse.org/EclipseLink/Examples/MOXy/GettingStarted

On the Tests class we will add an @XmlRootElement annotation. Doing this will let your JAXB implementation know that when a document starts with this element that it should instantiate this class. JAXB is configuration by exception, this means you only need to add annotations where your mapping differs from the default. Since the testData property differs from the default mapping we will use the @XmlElement annotation. You may find the following tutorial helpful: http://wiki.eclipse.org/EclipseLink/Examples/MOXy/GettingStarted

package forum11221136;

import javax.xml.bind.annotation.*;

@XmlRootElement
public class Tests {

    TestData testData;

    @XmlElement(name="test-data")
    public TestData getTestData() {
        return testData;
    }

    public void setTestData(TestData testData) {
        this.testData = testData;
    }

}

测试数据

在这个类中，我使用 @XmlType 注释来指定元素的排序顺序.我添加了一个似乎缺少的 testData 属性.出于与 Tests 类中相同的原因，我还使用了 @XmlElement 注释.

On this class I used the @XmlType annotation to specify the order in which the elements should be ordered in. I added a testData property that appeared to be missing. I also used an @XmlElement annotation for the same reason as in the Tests class.

package forum11221136;

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

@XmlType(propOrder={"title", "book", "count", "testData"})
public class TestData {
    String title;
    String book;
    String count;
    List<TestData> testData;

    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public String getBook() {
        return book;
    }
    public void setBook(String book) {
        this.book = book;
    }
    public String getCount() {
        return count;
    }
    public void setCount(String count) {
        this.count = count;
    }
    @XmlElement(name="test-data")
    public List<TestData> getTestData() {
        return testData;
    }
    public void setTestData(List<TestData> testData) {
        this.testData = testData;
    }
}

演示

下面是一个示例，说明如何使用 JAXB API 读取(解组)XML 并填充您的域模型，然后将结果写回(编组)回 XML.

Below is an example of how to use the JAXB APIs to read (unmarshal) the XML and populate your domain model and then write (marshal) the result back to XML.

package forum11221136;

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

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance(Tests.class);

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        File xml = new File("src/forum11221136/input.xml");
        Tests tests = (Tests) unmarshaller.unmarshal(xml);

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(tests, System.out);
    }

}

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