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java如何使用JAXB对有时包含XML内容,有时不包含XML内容的字符串进行整理?

考虑这个例子-

我有一个名为Report的类,它有一个Message类型的字段。消息类有一个名为“body”的字段,它是一个字符串。“body”可以是任何字符串,但有时它包含格式正确的XML内容。如何确保当“body”包含XML内容时,序列化采用XML结构的形式,而不是它目前提供的形式

以下是带有输出的代码-

报告课堂

import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;

@XmlRootElement(name = "Report")
@XmlType(propOrder = { "message"})
public class Report
{
    private Message message;
    public Message getMessage() { return message; }
    public void setMessage(Message m) { message = m; }
}

消息

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlType;

@XmlType(propOrder = { "body" })
public class Message
{
    private String body;
    public String getBody() { return body; }
    @XmlElement
    public void setBody(String body) { this.body = body; }
}

主要

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;



public class SerializationTest
{
    public static void main(String args[]) throws Exception
    {
       JAXBContext jaxbContext = JAXBContext.newInstance(Report.class);
       Marshaller jaxbMarshaller = jaxbContext.createMarshaller();
       jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

       Report report = new Report();
       Message message = new Message();

       message.setBody("Sample report message.");
       report.setMessage(message);
       jaxbMarshaller.marshal(report, System.out);

       message.setBody("<rootTag><body>All systems online.</body></rootTag>");
       report.setMessage(message);
       jaxbMarshaller.marshal(report, System.out);
    }
}

结果如下:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<Report>
    <message>
        <body>Sample report message.</body>
    </message>
</Report>
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<Report>
    <message>
        <body>&lt;rootTag&gt;&lt;body&gt;All systems online.&lt;/body&gt;&lt;/rootTag&gt;</body>
    </message>
</Report>

正如您在上面的输出中所看到的,对于“body”的第二个实例,产生了序列化

 <body>&lt;rootTag&gt;&lt;body&gt;All systems online.&lt;/body&gt;&lt;/rootTag&gt;</body>

而不是

<body><rootTag><body>All systems online.</body></rootTag></body>

如何解决这个问题


共 (3) 个答案

  1. # 1 楼答案

    3种不同的解决方案1)、2)3),如下所示:

    1)以下帖子是对您的解决方案Loresh的描述:

    http://anna-safronova.livejournal.com/2524.html?thread=9180

    这仍然缺少详细信息

    • 对于Embeded html,我们需要一个<![CDATA

    • JAXB的依赖性

    com。太阳xml。绑定马歇尔。角色逃逸者

    需要导入jaxb impl进行编译/执行,例如

    <groupId>com.sun.xml.bind</groupId>
    <artifactId>jaxb-impl</artifactId>  
     <version>2.2.4</version>
    
    • 限制:此解决方案是特定于容器的,可能由于类加载策略而无法运行

    2)另一种类似的方法是JDK的rt.jar依赖性

    com。太阳xml。内部的绑定角色逃逸者

    http://theopentutorials.com/tutorials/java/jaxb/jaxb-marshalling-and-unmarshalling-cdata-block/

    同样的限制/依赖于目标JDK,Eclipse/Maven上的一些调整也是必要的(糟糕的选择/我的意见)

    3)最后,在Reg Whitton的另一篇文章中找到了最佳解决方案:

    https://stackoverflow.com/a/12637295/560410

    这是详细的接收:

    http://javacoalface.blogspot.co.uk/2012/09/outputting-cdata-sections-with-jaxb.html

    这对我来说太完美了

  2. # 2 楼答案

    如果仅用于编组,则忽略<;及;, 我们可以使用以下方法:

    marshaller.setProperty("com.sun.xml.bind.marshaller.CharacterEscapeHandler",
                    new CharacterEscapeHandler() {
                        @Override
                        public void escape(char[] ac, int i, int j, boolean flag,
                                Writer writer) throws IOException {
                            writer.write(ac, i, j);
                        }
                    });
    
  3. # 3 楼答案

    注意:我是EclipseLink JAXB (MOXy)领导和JAXB (JSR-222)专家组成员

    使用@XmlAnyElement注释并指定DOMHandler来映射此用例。在使用JAXB RI执行此操作时,似乎存在错误,但以下用例适用于EclipseLink JAXB(MOXy)

    BodyDomainHandler

    默认情况下,JAXB实现将未映射的内容表示为DOM节点。您可以利用DomHandler作为DOM的替代表示,在本例中,我们将DOM表示为String

    import java.io.*;
    import javax.xml.bind.ValidationEventHandler;
    import javax.xml.bind.annotation.DomHandler;
    import javax.xml.transform.Source;
    import javax.xml.transform.stream.*;
    
    public class BodyDomHandler implements DomHandler<String, StreamResult> {
    
        private static final String BODY_START_TAG = "<body>";
        private static final String BODY_END_TAG = "</body>";
    
        private StringWriter xmlWriter = new StringWriter();
    
        public StreamResult createUnmarshaller(ValidationEventHandler errorHandler) {
            return new StreamResult(xmlWriter);
        }
    
        public String getElement(StreamResult rt) {
            String xml = rt.getWriter().toString();
            int beginIndex = xml.indexOf(BODY_START_TAG) + BODY_START_TAG.length();
            int endIndex = xml.indexOf(BODY_END_TAG);
            return xml.substring(beginIndex, endIndex);
        }
    
        public Source marshal(String n, ValidationEventHandler errorHandler) {
            try {
                String xml = BODY_START_TAG + n.trim() + BODY_END_TAG;
                StringReader xmlReader = new StringReader(xml);
                return new StreamSource(xmlReader);
            } catch(Exception e) {
                throw new RuntimeException(e);
            }
        }
    
    }
    

    消息

    下面是如何在Message类上指定@XmlAnyElement注释

    import javax.xml.bind.annotation.XmlAnyElement;
    import javax.xml.bind.annotation.XmlType;
    
    @XmlType(propOrder = { "body" })
    public class Message
    {
        private String body;
        public String getBody() { return body; }
        @XmlAnyElement(BodyDomHandler.class)
        public void setBody(String body) { this.body = body; }
    }
    

    输出

    下面是运行SerialziationTest的输出:

    <?xml version="1.0" encoding="UTF-8"?>
    <Report>
       <message>
          <body>Sample report message.</body>
       </message>
    </Report>
    <?xml version="1.0" encoding="UTF-8"?>
    <Report>
       <message>
          <body>
             <rootTag>
                <body>All systems online.</body>
             </rootTag>
          </body>
       </message>
    </Report>
    

    了解更多信息

    注意-JAXB RI中的Bug

    JAXB参考实现中似乎有一个bug,示例代码将产生如下堆栈跟踪:

    Exception in thread "main" javax.xml.bind.MarshalException
     - with linked exception:
    [com.sun.istack.internal.SAXException2: unable to marshal type "java.lang.String" as an element because it is missing an @XmlRootElement annotation]
        at com.sun.xml.internal.bind.v2.runtime.MarshallerImpl.write(MarshallerImpl.java:317)
        at com.sun.xml.internal.bind.v2.runtime.MarshallerImpl.marshal(MarshallerImpl.java:243)
        at javax.xml.bind.helpers.AbstractMarshallerImpl.marshal(AbstractMarshallerImpl.java:75)
        at forum12428727.SerializationTest.main(SerializationTest.java:20)
    Caused by: com.sun.istack.internal.SAXException2: unable to marshal type "java.lang.String" as an element because it is missing an @XmlRootElement annotation
        at com.sun.xml.internal.bind.v2.runtime.XMLSerializer.reportError(XMLSerializer.java:216)
        at com.sun.xml.internal.bind.v2.runtime.LeafBeanInfoImpl.serializeRoot(LeafBeanInfoImpl.java:126)
        at com.sun.xml.internal.bind.v2.runtime.property.SingleReferenceNodeProperty.serializeBody(SingleReferenceNodeProperty.java:100)
        at com.sun.xml.internal.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:306)
        at com.sun.xml.internal.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:664)
        at com.sun.xml.internal.bind.v2.runtime.property.SingleElementNodeProperty.serializeBody(SingleElementNodeProperty.java:141)
        at com.sun.xml.internal.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:306)
        at com.sun.xml.internal.bind.v2.runtime.XMLSerializer.childAsSoleContent(XMLSerializer.java:561)
        at com.sun.xml.internal.bind.v2.runtime.ClassBeanInfoImpl.serializeRoot(ClassBeanInfoImpl.java:290)
        at com.sun.xml.internal.bind.v2.runtime.XMLSerializer.childAsRoot(XMLSerializer.java:462)
        at com.sun.xml.internal.bind.v2.runtime.MarshallerImpl.write(MarshallerImpl.java:314)
        ... 3 more