java 从 JAXB 泛型中删除 xsi:type、xmlns:xs 和 xmlns:xsi
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原文地址: http://stackoverflow.com/questions/11192623/
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Remove xsi:type, xmlns:xs, and xmlns:xsi from JAXB Generics
提问by RedHackTea
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.
使用 JAXB 时，我想在使用泛型时从我的 XML 元素中删除多余的命名空间/类型。我该怎么做，或者我做错了什么？我想使用泛型，这样我只需编写一次代码块。
Example code:
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)
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:
输出：
<?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>
采纳答案by bdoughan
Test Generic
测试通用
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 valuefield as type Object. This will result in the xsi:typeattributes as your JAXB implementation is adding enough information to be able to unmarshal the same types.
您的 JAXB (JSR-222) 实现将创建每个类的映射（即TestGeneric，不是类型（即TestGeneric<Integer>）。因此，它将将该value字段视为 type Object。这将导致xsi:type属性，因为您的 JAXB 实现正在添加足够的信息能够解组相同的类型。
@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
演示
Below is an approach you could use. I have introduced subclasses of TestGenericto represent the different possible types.
以下是您可以使用的方法。我已经引入了 的子类TestGeneric来表示不同的可能类型。
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;
}
}
}
回答by D-Thurm
I was able to use @XmlAnyElement(lax=true) on the property that was causing me problems due to the generic parameter, then had to add an @XmlRootElement on the actual class that was being marshalled, and the declaration went away! Fantastic!
我能够在由于泛型参数而导致我出现问题的属性上使用 @XmlAnyElement(lax=true)，然后不得不在正在编组的实际类上添加 @XmlRootElement，并且声明消失了！极好的！
回答by user2967586
i get the same problem, and resolved it by the advice from Programmatically determine if a JAXB annotation will result in a xsi:type annotation?
我遇到了同样的问题，并根据Programmatically 确定 JAXB 批注是否会导致 xsi:type 批注的建议解决了这个问题 。
just using @XmlAnyElement(lax=true)instead of using @XmlElementon the generic class object (value for this sample).
只是使用@XmlAnyElement(lax=true)而不是@XmlElement在通用类对象上使用（此示例的值）。
