从JAXB Generics中删除xsi：type，xmlns：xs和xmlns：xsi [英] Remove xsi:type, xmlns:xs, and xmlns:xsi from JAXB Generics

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问题描述

使用JAXB时，我想在使用泛型时从我的XML元素中删除多余的名称空间/类型。我该怎么做，或者我做错了什么？我希望使用泛型，这样我只需编写一段代码即可。



示例代码：

  public static void main（String [] args）{
 try {
 TestRoot root = new TestRoot（）; 
 root.name.value =bobby; 
 root.age.value = 102; 
 root.color.value =blue; 
 
 JAXBContext context = JAXBContext.newInstance（root.getClass（））; 
 Marshaller marsh = context.createMarshaller（）; 
 marsh.setProperty（Marshaller.JAXB_ENCODING，UTF-8）; 
 marsh.setProperty（Marshaller.JAXB_FORMATTED_OUTPUT，Boolean.TRUE）; 
 
 StringWriter sw = new StringWriter（）; 
 PrintWriter pw = new PrintWriter（sw）; 
 marsh.marshal（root，pw）; 
 System.out.println（sw.toString（））; 
} 
 catch（Throwable t）{
 t.printStackTrace（）; 
 
 
 
 @XmlRootElement 
 static class TestRoot {
 @XmlElement public TestGeneric< String> name = new TestGeneric< String>（true）; 
 @XmlElement public TestGeneric< Integer> age = new TestGeneric< Integer>（true）; 
 @XmlElement public TestWhatIWouldLike color = new TestWhatIWouldLike（true）; 
} 
 
 @XmlAccessorType（XmlAccessType.NONE）
静态类TestGeneric< T> {
 @XmlAttribute public boolean isRequired; 
 @XmlElement公共T值; 
 $ b $ public TestGeneric（）{
} 
 
 public TestGeneric（boolean isRequired）{
 this.isRequired = isRequired; 
 
 
 $ b @XmlAccessorType（XmlAccessType.NONE）
静态类TestWhatIWouldLike {
 @XmlAttribute public boolean isRequired; 
 @XmlElement public String value; 
 $ b $ public TestWhatIWouldLike（）{
} 
 
 public TestWhatIWouldLike（boolean isRequired）{
 this.isRequired = isRequired; 
 
 
 $ / code $ / pre 
 $ b $输出：
 
 
 <？xml version =1.0encoding =UTF-8standalone =yes？> 
< testRoot> 
< name isRequired =true> 
<值xsi：type =xs：stringxmlns：xs =http://www.w3.org/2001/XMLSchemaxmlns：xsi =http://www.w3.org/ 2001 / XMLSchema的实例>发夹< /值GT; 
< / name> 
< age isRequired =true> 
<值xsi：type =xs：intxmlns：xs =http://www.w3.org/2001/XMLSchemaxmlns：xsi =http://www.w3.org/ 2001 / XMLSchema的实例> 102< /值GT; 
< / age> 
< color isRequired =true> 
<值>蓝色< /值> 
< / color> 
< / testRoot> 
  
 
 
解决方案
  Test Generic   TestGeneric ，而不是类型（即 TestGeneric< Integer> ）。因此，它会将值字段视为类型 Object 这会导致 xsi：type 属性，因为您的JAXB实现正在添加足够的信息来解组相同的类型。
  @XmlAccessorType（XmlAccessType.NONE）
静态类TestGeneric< T> {
 @XmlAttribute public boolean isRequired; 
 @XmlElement public T value; 
 $ b $ public TestGeneric（）{
} 
 $ b $ public TestGeneric（boolean isRequired）{
 this.isRequired = isRequired; 
} 
} 
  
 
 
 
 
 
 
 演示  
 
 
以下是您可以采用的方法我已经引入了 TestGeneric 的子类来表示不同的可能类型。
 包论坛11192623; 
 
 import java.io.PrintWriter; 
 import java.io.StringWriter; 
 
 import javax.xml.bind。*; 
 import javax.xml.bind.annotation。*; 
 
 public class Demo {
 
 public static void main（String [] args）{
 try {
 TestRoot root = new TestRoot（）; 
 root.name.value =bobby; 
 root.age.value = 102; 
 root.color.value =blue; 
 
 JAXBContext context = JAXBContext.newInstance（root.getClass（））; 
 Marshaller marsh = context.createMarshaller（）; 
 marsh.setProperty（Marshaller.JAXB_ENCODING，UTF-8）; 
 marsh.setProperty（Marshaller.JAXB_FORMATTED_OUTPUT，Boolean.TRUE）; 
 
 StringWriter sw = new StringWriter（）; 
 PrintWriter pw = new PrintWriter（sw）; 
 marsh.marshal（root，pw）; 
 System.out.println（sw.toString（））; 
} 
 catch（Throwable t）{
 t.printStackTrace（）; 
 
 
 
 @XmlRootElement 
 static class TestRoot {
 @XmlElement public TestString name = new TestString（true）; 
 @XmlElement public TestInteger age = new TestInteger（true）; 
 @XmlElement public TestString color = new TestString（true）; 
 
 $ b @XmlAccessorType（XmlAccessType.NONE）
 @XmlTransient 
 @XmlSeeAlso（{TestInteger.class，TestString.class}）
静态类TestGeneric< ; T> {
 @XmlAttribute 
 public boolean isRequired; 
公共T值; 
 $ b $ public TestGeneric（）{
} 
 
 public TestGeneric（boolean isRequired）{
 this.isRequired = isRequired; 
} 
} 
 
 static class TestInteger extends TestGeneric< Integer> {
 public TestInteger（）{
} 
 public TestInteger（boolean b）{
 super（b）; 
} 
 @XmlElement 
 public Integer getValue（）{
返回值; 
} 
 public void setValue（Integer value）{
 this.value = value; 
} 
} 
 
静态类TestString extends TestGeneric< String> {
 public TestString（）{
} 
 public TestString（boolean b）{
 super（b）; 
} 
 @XmlElement 
 public String getValue（）{
返回值; 
} 
 public void setValue（String value）{
 this.value = value; 
} 
} 
 
} 
  
 
When using JAXB, I'd like to remove the excess namespaces/types from my XML elements when using Generics.  How can I do this or what am I doing wrong?  I'd like to use Generics so that I only have to write a block of code once.



Example code:
public static void main(String[] args) {
    try {
        TestRoot root = new TestRoot();
        root.name.value = "bobby";
        root.age.value = 102;
        root.color.value = "blue";

        JAXBContext context = JAXBContext.newInstance(root.getClass());
        Marshaller marsh = context.createMarshaller();
        marsh.setProperty(Marshaller.JAXB_ENCODING,"UTF-8");
        marsh.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT,Boolean.TRUE);

        StringWriter sw = new StringWriter();
        PrintWriter pw = new PrintWriter(sw);
        marsh.marshal(root,pw);
        System.out.println(sw.toString());
    }
    catch(Throwable t) {
        t.printStackTrace();
    }
}

@XmlRootElement
static class TestRoot {
    @XmlElement public TestGeneric<String> name = new TestGeneric<String>(true);
    @XmlElement public TestGeneric<Integer> age = new TestGeneric<Integer>(true);
    @XmlElement public TestWhatIWouldLike color = new TestWhatIWouldLike(true);
}

@XmlAccessorType(XmlAccessType.NONE)
static class TestGeneric<T> {
    @XmlAttribute public boolean isRequired;
    @XmlElement public T value;

    public TestGeneric() {
    }

    public TestGeneric(boolean isRequired) {
        this.isRequired = isRequired;
    }
}

@XmlAccessorType(XmlAccessType.NONE)
static class TestWhatIWouldLike {
    @XmlAttribute public boolean isRequired;
    @XmlElement public String value;

    public TestWhatIWouldLike() {
    }

    public TestWhatIWouldLike(boolean isRequired) {
        this.isRequired = isRequired;
    }
}

Output:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<testRoot>
    <name isRequired="true">
        <value xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">bobby</value>
    </name>
    <age isRequired="true">
        <value xsi:type="xs:int" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">102</value>
    </age>
    <color isRequired="true">
        <value>blue</value>
    </color>
</testRoot>



 解决方案 
Test Generic



Your JAXB (JSR-222) implementation is going to create mappings per class (i.e. TestGeneric, not type (i.e. TestGeneric<Integer>).  As such it is going to treat the value field as type Object.  This will result in the xsi:type attributes as your JAXB implementation is adding enough information to be able to unmarshal the same types.
@XmlAccessorType(XmlAccessType.NONE)
static class TestGeneric<T> {
    @XmlAttribute public boolean isRequired;
    @XmlElement public T value;

    public TestGeneric() {
    }

    public TestGeneric(boolean isRequired) {
        this.isRequired = isRequired;
    }
}







Demo



Below is an approach you could use.  I have introduced subclasses of TestGeneric to represent the different possible types.
package forum11192623;

import java.io.PrintWriter;
import java.io.StringWriter;

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

public class Demo {

    public static void main(String[] args) {
        try {
            TestRoot root = new TestRoot();
            root.name.value = "bobby";
            root.age.value = 102;
            root.color.value = "blue";

            JAXBContext context = JAXBContext.newInstance(root.getClass());
            Marshaller marsh = context.createMarshaller();
            marsh.setProperty(Marshaller.JAXB_ENCODING,"UTF-8");
            marsh.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT,Boolean.TRUE);

            StringWriter sw = new StringWriter();
            PrintWriter pw = new PrintWriter(sw);
            marsh.marshal(root,pw);
            System.out.println(sw.toString());
        }
        catch(Throwable t) {
            t.printStackTrace();
        }
    }

    @XmlRootElement
    static class TestRoot {
        @XmlElement public TestString name = new TestString(true);
        @XmlElement public TestInteger age = new TestInteger(true);
        @XmlElement public TestString color = new TestString(true);
    }

    @XmlAccessorType(XmlAccessType.NONE)
    @XmlTransient
    @XmlSeeAlso({TestInteger.class, TestString.class})
    static class TestGeneric<T> {
        @XmlAttribute 
        public boolean isRequired;
        public T value;

        public TestGeneric() {
        }

        public TestGeneric(boolean isRequired) {
            this.isRequired = isRequired;
        }
    }

    static class TestInteger extends TestGeneric<Integer> {
        public TestInteger() {
        }
        public TestInteger(boolean b) {
            super(b);
        }
        @XmlElement
        public Integer getValue() {
            return value;
        }
        public void setValue(Integer value) {
            this.value = value;
        }
    }

    static class TestString extends TestGeneric<String> {
        public TestString() {
        }
        public TestString(boolean b) {
            super(b);
        }
        @XmlElement
        public String getValue() {
            return value;
        }
        public void setValue(String value) {
            this.value = value;
        }
    }

}



                        
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