使用默认值初始化JAXB对象

问题描述

JAXB几乎没有问题。

鉴于：

• Java 1.5;来自jaxws-2_0的jaxb -jars。


• .xsd方案和生成的JAXB类。


• .xsd中的每个简单元素都有默认值。结果类成员的注释类似于
  @XmlElement（name =cl_fname，required = true，defaultValue =[ _ __ _ __]）

• Java 1.5; jaxb -jars from jaxws-2_0.
• .xsd scheme and generated JAXB classes.
• Every simple element in .xsd has default value. And as result class members has annotations like"@XmlElement(name = "cl_fname", required = true, defaultValue = "[______]")"

必需

获取完全代表xml的java对象（根元素）以及默认值初始化的每个成员。

Get java object (root element) which fully represent xml and every member initialized by default values.

当我尝试在没有明确设置值的情况下编组xml时，默认值不会显示...是否有任何使用默认值填充的marshall xml的方法，而无需自定义生成的类？

when I try to marshall xml without explicitly setting values, default values doesn't make sence... is there any way to marshall xml populated with default values without customization of generated classes?

.xsd的例子：

<xs:element name="document">
    <xs:complexType>
        <xs:sequence>
            <xs:element ref="d_int"/>
            <xs:element ref="d_double"/>
            <xs:element ref="d_string"/>
        </xs:sequence>
    </xs:complexType>
</xs:element>

<xs:element name="d_int" type="xs:int" default="-1"/>
<xs:element name="d_double" type="xs:double" default="-1.0"/>
<xs:element name="d_string" type="xs:string" default="false"/>

和java class：

public class Document {
    @XmlElement(name = "d_int", defaultValue = "-1")
    protected int dInt;
    @XmlElement(name = "d_double", defaultValue = "-1.0")
    protected double dDouble;
    @XmlElement(name = "d_string", required = true, defaultValue = "Default")
    protected String dString;
...
}

推荐答案

注释中的默认值仅在解组之后才有效。

解组此

default value that is in annotations works only after unmarshalling.
unmarshal this

<document>
   <d_int/>
   <d_double/>
   <d_string/>
</document>

您将获得具有默认值的对象（-1，-1.0，默认）

and you will get object with default values (-1, -1.0, "Default")

如果你想将默认值设置为编组，你应该这样做

If you want set default values to marshalling, you should do this

public class Document {
    @XmlElement(name = "d_int", defaultValue = "-1")
    protected int dInt = 100;
    @XmlElement(name = "d_double", defaultValue = "-1.0")
    protected double dDouble = -100;
    @XmlElement(name = "d_string", required = true, defaultValue = "Default")
    protected String dString = "def";
...
}

jaxb仅为解组生成默认值

jaxb generate default values only for unmarshalling

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