JAXB元素映射

Question

我有一個類似的xml：

    <alpha>
            <beta>
                    <theta>abcd</theta>
            </beta>
    </alpha>

我想將theta元素映射到MyBean類中的thetaValue屬性

@XmlRootElement(name = "alpha")
public class MyBean {
    private String thetaValue;

    public String getThetaValue() {
        return this.thetaValue;
    }

    public void setThetaValue(String thetaValue) {
        this.thetaValue= thetaValue;
    }
}

有什么辦法可以做到嗎？ 我正在使用JDK 1.6隨附的jaxb

Answer 1

注意：我是EclipseLink JAXB（MOXy）的負責人，並且是JAXB（JSR-222）專家組的成員。

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使用任何JAXB（JSR-222）實現

使用任何JAXB（JSR-222）實現，都可以使用XmlAdapter映射此用例。

ThetaValueAdapter

package forum9799081;

import javax.xml.bind.annotation.adapters.XmlAdapter;

public class ThetaValueAdapter extends XmlAdapter<ThetaValueAdapter.Beta, String> {

    @Override
    public Beta marshal(String string) throws Exception {
        Beta beta = new Beta();
        beta.theta = string;
        return beta;
    }

    @Override
    public String unmarshal(Beta beta) throws Exception {
        return beta.theta;
    }

    public static class Beta {
        public String theta;
    }

}

為myBean

package forum9799081;

import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;

@XmlRootElement(name = "alpha")
public class MyBean {
    private String thetaValue;

    @XmlElement(name="beta")
    @XmlJavaTypeAdapter(ThetaValueAdapter.class)
    public String getThetaValue() {
        return this.thetaValue;
    }

    public void setThetaValue(String thetaValue) {
        this.thetaValue = thetaValue;
    }

}

演示

package forum9799081;

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

public class Demo {

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

        File xml = new File("src/forum9799081/input.xml");
        Unmarshaller unmarshaller = jc.createUnmarshaller();
        MyBean myBean = (MyBean) unmarshaller.unmarshal(xml);

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

}

input.xml中/輸出

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<alpha>
    <beta>
        <theta>abcd</theta>
    </beta>
</alpha>

---

使用EclipseLink JAXB（MOXy）

使用MOXy，您可以使用@XmlPath擴展來實現相同的映射：

package forum9799081;

import javax.xml.bind.annotation.*;
import org.eclipse.persistence.oxm.annotations.XmlPath;

@XmlRootElement(name = "alpha")
public class MyBean {
    private String thetaValue;

    @XmlPath("beta/theta/text()")
    public String getThetaValue() {
        return this.thetaValue;
    }

    public void setThetaValue(String thetaValue) {
        this.thetaValue = thetaValue;
    }

}

欲獲得更多信息

• http://blog.bdoughan.com/2010/07/xpath-based-mapping.html
• http://blog.bdoughan.com/2011/09/mapping-objects-to-multiple-xml-schemas.html
• http://blog.bdoughan.com/2011/05/specifying-eclipselink-moxy-as-your.html