JAXB ValidationEventHandler的句柄事件方法未被调用

Question

我试图捕获一个ValidationEvent，其中包含XML规则中不允许使用的字符。（例如，”

我已经阅读了描述unmarshal方法的Javadoc。但是，我没有看到它无法捕获ValidationEvent。

从指定的InputStream中解组XML数据并返回结果内容树。使用此形式的解组API时，验证事件位置信息可能不完整。

在最后一次尝试中，我尝试在网上搜索，但什么也找不到<任何帮助都将不胜感激：D

我很抱歉补充一个问题。（POJO类有点变化…）我用@XmlPath注释定义了POJO类字段，与XML元素名不同，但它似乎不起作用。我应该将其用作XmlElement吗？

import org.eclipse.persistence.oxm.annotations.XmlPath;

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import java.util.List;

@XmlRootElement
class Article {
    private String title;
    private String category;
    private List<ArticleImage> imageList;

    public String getTitle() {
        return title;
    }

    @XmlElement
    public void setTitle(String title) {
        this.title = title;
    }

    public String getCategory() {
        return category;
    }

    @XmlElement
    public void setCategory(String category) {
        this.category = category;
    }

    public List<ArticleImage> getImageList() {
        return imageList;
    }

    // for Extra Question... :D
    @XmlPath("image")
    public void setImageList(List<ArticleImage> imageList) {
        this.imageList = imageList;
    }
}

class ArticleImage {
    private String url;
    private String ext;

    public String getUrl() {
        return url;
    }

    @XmlAttribute
    public void setUrl(String url) {
        this.url = url;
    }

    public String getExt() {
        return ext;
    }

    @XmlAttribute
    public void setExt(String ext) {
        this.ext = ext;
    }
}

import javax.xml.bind.ValidationEvent;
import javax.xml.bind.ValidationEventHandler;
import javax.xml.bind.ValidationEventLocator;

class CustomValidationHandler implements ValidationEventHandler {

    // This method is not reached when debugging.
    @Override
    public boolean handleEvent(ValidationEvent event) {
        if (event.getSeverity() == ValidationEvent.FATAL_ERROR ||
                event.getSeverity() == ValidationEvent.ERROR) {
            ValidationEventLocator locator = event.getLocator();
            throw new RuntimeException("Error in EventHandler. line number: " + locator.getLineNumber());
        }
        return true;
    }
}

import org.eclipse.persistence.jaxb.JAXBContextFactory;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Unmarshaller;
import java.io.ByteArrayInputStream;
import java.io.InputStream;

public class SomeTest {

    public void someMethod() {
        String xmlString = "<article type=\"item\">\n"
                + "    <title>M&A</title>\n"
                + "    <category>1234-1234</category>\n"
                + "    <image url=\"hello\" ext=\"jpg\"/>\n"
                + "</article>";

        try (InputStream fileInputStream = new ByteArrayInputStream(xmlString.getBytes())) {
            JAXBContext context = JAXBContextFactory.createContext(new Class[]{Article.class}, null);
            Unmarshaller unmarshaller = context.createUnmarshaller();
            unmarshaller.setEventHandler(new CustomValidationHandler());
            Article article = (Article) unmarshaller.unmarshal(fileInputStream);

            System.out.println(article.getTitle());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        new SomeTest().someMethod();
    }
}

Answer 1

它适用于两种情况：InputStream和StringReader

只是改变了这一点：

JAXBContext context = JAXBContext.newInstance(Article.class);

Answer 2

正如@Mart和@Sergey所说

更新JAXBContext context=JAXBContextFactory。createContext（新类[]{Article.Class}，null）；

   JAXBContext context = JAXBContext.newInstance(Article.class);

并添加@XmlAccessorType（XmlAccessType.Field）在你的文章pojo类中。

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class Article {
    @XmlElement
    private String title;
    @XmlElement
    private String category;

//setter getters

}

我已经检查过了，如果出现异常，将调用CustomValidationHandler。

Answer 3

最初建议替换

JAXBContext context = JAXBContextFactory.createContext(new Class[]{Article.class}, null);

到

JAXBContext context = JAXBContext.newInstance(Article.class);

在JAXBContextFactory的实现中。createContext您可以看到classesToBeBound（在您的例子中，您将通过本文）执行一些检查，这些检查导致异常“无法找到要委托的JAXB实现”。这就是我在运行代码时遇到的问题，我认为您也遇到了。然后调用了事件处理程序（至少在我的设置中是这样）。

后来您遇到了“…类有两个同名属性”value“…的问题我建议检查这个链接，这解释了它发生的原因。

链接是：在字段之前使用@XmlElement和在getter声明之前使用@XmlElement有什么区别？

编辑以答复新问题：

如果你不介意我问你想用@XmlPath（“image”）做什么？

您的POJO结构与xml不匹配。删除注释并更改图像的setter方法，如下所示：

@XmlRootElement
class Article {
    private String title;
    private String category;
    private List<ArticleImage> imageList;

    public String getTitle() {
        return title;
    }

    @XmlElement
    public void setTitle(String title) {
        this.title = title;
    }

    public String getCategory() {
        return category;
    }

    @XmlElement
    public void setCategory(String category) {
        this.category = category;
    }

    public List<ArticleImage> getImage() {
        return imageList;
    }

    // for Extra Question... :D
    // method name changed!
    public void setImage(List<ArticleImage> imageList) {
        this.imageList = imageList;
    }
}

class ArticleImage {
    private String url;
    private String ext;

    public String getUrl() {
        return url;
    }

    @XmlAttribute
    public void setUrl(String url) {
        this.url = url;
    }

    public String getExt() {
        return ext;
    }

    @XmlAttribute
    public void setExt(String ext) {
        this.ext = ext;
    }
}