正如上面的答案之一所暗示的，如果在XSD中根元素的类型定义为命名类型，则根元素上不会有XMLRootElement，因为该命名类型可以在XSD中的其他地方使用。尝试将其转换为匿名类型，即:

<xsd:element name="myRootElement" type="MyRootElementType" />

<xsd:complexType name="MyRootElementType">
...
</xsd:complexType>

你会:

<xsd:element name="myRootElement">
    <xsd:complexType>
    ...
    <xsd:complexType>
</xsd:element>

JAXBElement包装器适用于JAXB没有生成@XmlRootElement的情况。这些包装器在maven-jaxb2-plugin生成的ObjectFactory类中可用。如:

     public class HelloWorldEndpoint {
        @PayloadRoot(namespace = NAMESPACE_URI, localPart = "person")
        @ResponsePayload
        public JAXBElement<Greeting> sayHello(@RequestPayload JAXBElement<Person> request) {

        Person person = request.getValue();

        String greeting = "Hello " + person.getFirstName() + " " + person.getLastName() + "!";

        Greeting greet = new Greeting();
        greet.setGreeting(greeting);

        ObjectFactory factory = new ObjectFactory();
        JAXBElement<Greeting> response = factory.createGreeting(greet);
        return response;
      }
 }

上面已经链接的博客文章底部提到了这一点，但这对我来说就像一种享受:

Marshaller marshaller = jc.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
marshaller.marshal(new JAXBElement<MyClass>(new QName("uri","local"), MyClass.class, myClassInstance), System.out);

因此，我使用mavens maven-jaxb2-plugin从一个大而复杂的WSDL文件生成类，并遇到了这个问题。问题是WSDL中的元素引用了complexType定义作为类型，因此没有生成元素类，并且在尝试使用complexType类时产生了缺少的@XmlRootElement错误。

在我看来，修改WSDL并不是一个切实可行的解决方案，唯一可行的方法似乎是设计一种在生成过程中添加缺失注释的方法。它还会在编组时引起序列化问题，因为请求发送了错误的元素名称，而且响应中也没有具有匹配元素名称的类。

最后我使用了第二个maven插件jaxb2-basic - annotation，它允许您通过使用jaxb绑定文件将缺少的注释添加到所需的类中。这使您不必在不添加不必要代码的情况下对这个问题进行排序，也意味着如果将来需要使用更新的WSDL文件，您可以轻松地重新生成。

pom.xml(注意，在配置中有一个插件部分用于执行- WSDL文件的位置是/src/main/resources/ WSDL /EstimatingService.wsdl)

<project>
    ...
    <properties>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
        <jaxb2.version>0.14.0</jaxb2.version>
        <jaxb2.annotate.version>1.1.0</jaxb2.annotate.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.jvnet.jaxb2.maven2</groupId>
            <artifactId>maven-jaxb2-plugin</artifactId>
            <version>${jaxb2.version}</version>
        </dependency>
        <dependency>
            <groupId>org.jvnet.jaxb2_commons</groupId>
            <artifactId>jaxb2-basics-annotate</artifactId>
            <version>${jaxb2.annotate.version}</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.jvnet.jaxb2.maven2</groupId>
                <artifactId>maven-jaxb2-plugin</artifactId>
                <version>${jaxb2.version}</version>
                <executions>
                    <execution>
                        <id>estimating</id>
                        <goals>
                            <goal>generate</goal>
                        </goals>
                        <configuration>
                            <schemaLanguage>WSDL</schemaLanguage>
                            <generateDirectory>target/generated-sources/acme/src/gen/estimating-service</generateDirectory>
                            <generatePackage>com.acme.shipping.estimating.service</generatePackage>
                            <schemaDirectory>${project.basedir}/src/main/resources/wsdl</schemaDirectory>
                            <schemaIncludes>
                                <include>EstimatingService.wsdl</include>
                            </schemaIncludes>
                            <bindingDirectory>${project.basedir}/src/main/resources/bindings</bindingDirectory>
                            <bindingIncludes>estimateServiceBinding.xjb</bindingIncludes>
                            <extension>true</extension>
                            <args>
                                <arg>-Xannotate</arg>
                                <arg>-XremoveAnnotation</arg>
                            </args>
                            <plugins>
                                <plugin>
                                    <groupId>org.jvnet.jaxb2_commons</groupId>
                                    <artifactId>jaxb2-basics-annotate</artifactId>
                                </plugin>
                            </plugins>
                        </configuration>
                    </execution>
                    ...
                    // More executions here if you have multiple WSDL files (Dont forget to give it a different package name and id)
                </executions>
            </plugin>
        </plugins>
    </build>
    ...
</project>  

estimateServiceBinding。xjb(本例中使用的jaxb绑定文件- /src/main/resources/bindings/ estimateservicbbinding .xjb)

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<jaxb:bindings version="2.0" xmlns:jaxb="http://java.sun.com/xml/ns/jaxb" xmlns:xjc="http://java.sun.com/xml/ns/jaxb/xjc" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:annox="http://annox.dev.java.net" xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/">
    <jaxb:globalBindings generateElementProperty="false">
        <xjc:simple />
    </jaxb:globalBindings>
    <!-- Target the schema section in the WSDL file using the given target namespace which contains the complexType definitions we want to annotate -->
    <jaxb:bindings schemaLocation="../wsdl/EstimatingService.wsdl" node="//xs:schema[@targetNamespace='http://acme.com/schema/datatypes/v2']">
        <jaxb:bindings node="xs:complexType[@name='GetQuickEstimateRequestContainer']">
            <!-- Add the @XmlRootElement annotation to the generated class and then tell it use the correct element name required when marshalling. e.g GetQuickEstimateRequestContainer element is renamed to the element name that referenced it in the WSDL (GetQuickEstimateRequest) -->
            <annox:annotateClass>@javax.xml.bind.annotation.XmlRootElement(name="GetQuickEstimateRequest")</annox:annotateClass>
        </jaxb:bindings>
        <jaxb:bindings node="xs:complexType[@name='GetQuickEstimateResponseContainer']">
            <annox:annotateClass>@javax.xml.bind.annotation.XmlRootElement(name="GetQuickEstimateResponse")</annox:annotateClass>
        </jaxb:bindings>
    </jaxb:bindings>
</jaxb:bindings>

生成带有@XmlRootElement注释和正确元素名称的类(GetQuickEstimateRequestContainer.java)

@XmlRootElement(name = "GetQuickEstimateRequest")
public class GetQuickEstimateRequestContainer {
    ...
    // class member fields & setters and getters
    ...
}

为了解决这个问题，你应该在使用wsimport编译之前配置一个xml绑定，将generateElementProperty设置为false。

     <jaxws:bindings wsdlLocation="LOCATION_OF_WSDL"
      xmlns:jaxws="http://java.sun.com/xml/ns/jaxws"
      xmlns:xjc="http://java.sun.com/xml/ns/jaxb/xjc" 
      xmlns:xs="http://www.w3.org/2001/XMLSchema"
      xmlns:jxb="http://java.sun.com/xml/ns/jaxb"
      xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/">
         <jaxws:enableWrapperStyle>false</jaxws:enableWrapperStyle>
    <jaxws:bindings  node="wsdl:definitions/wsdl:types/xs:schema[@targetNamespace='NAMESPACE_OF_WSDL']">
      <jxb:globalBindings xmlns:jxb="http://java.sun.com/xml/ns/jaxb" xmlns:xs="http://www.w3.org/2001/XMLSchema">
            <xjc:generateElementProperty>false</xjc:generateElementProperty> 
      </jxb:globalBindings>
  </jaxws:bindings>
</jaxws:bindings>

使用Maven构建，您可以添加@XmlRootElement注释

使用“jaxb2-basics- annotation”插件。

查看更多信息:参见

配置Maven以使用JAXB从XML Schema生成类

和JAXB XJC代码生成