使用属性和未包装的集合反序列化 XML 响应答案

【问题标题】：Deserialise XML response with attributes and not wrapped collections使用属性和未包装的集合反序列化 XML 响应
【发布时间】：2020-04-03 00:10:24
【问题描述】：

我正在尝试反序列化来自我的RestTemplate 的XML 响应，并且该响应包含我需要在映射对象中设置的属性。响应类似于：

<schoolResponse>
    <class id="1" num_of_students="22" name="Ms Barry" >
        <student key="202" value="Jim" />
        <student key="203" value="Tom" />
        <student key="204" value="Dave" />
        <schoolYear>1980</schoolYear>
    </class>
    <class id="2" num_of_students="20" name="Mr Smith">
        <student key="302" value="Jim" />
        <student key="303" value="Tom" />
        <student key="304" value="Dave" />
        <schoolYear>1980</schoolYear>
    </class>
    <class>
        ...
    </class>
</schoolResponse>

我的POJO 是：

@Data
@NoArgsConstructor
public class SchoolResponse {

    @JacksonXmlElementWrapper(localName = "class")
    private List<ClassRoomResponse> classes;

}


@Data
@NoArgsConstructor
@XmlRootElement(name="class")
public class ClassRoomResponse {

    @XmlAttribute(name = "id")
    private String id;

    @XmlAttribute(name = "num_of_students")
    private String numOfStudents;

    @XmlAttribute(name = "name")
    private String teacherName;

    @XmlElement(name = "schoolYear")
    private String schoolYear;

    @JacksonXmlElementWrapper(localName = "key")
    String key;

    @JacksonXmlElementWrapper(localName = "value")
    String value;

    public ClassRoomResponse(String stringSetter) {}
}

这个映射没有正确设置值，所以，我想知道我在使用这些属性时遇到了什么问题。

【问题讨论】：

以下答案有用吗？

标签： java xml spring-boot jackson lombok

【解决方案1】：

对于Student 节点，您需要一个额外的POJO。此外，您所有的收藏品都已打开。如果您混合使用JAXB 和Jackson 注释，您需要注册com.fasterxml.jackson.module.jaxb.JaxbAnnotationModule 模块。请参阅下面带有固定 POJO 类的示例：

import com.fasterxml.jackson.dataformat.xml.XmlMapper;
import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlElementWrapper;
import com.fasterxml.jackson.module.jaxb.JaxbAnnotationModule;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import java.io.File;
import java.io.IOException;
import java.util.List;

public class XmlMapperApp {

    public static void main(String... args) throws IOException {
        File xmlFile = new File("./resource/test.xml").getAbsoluteFile();

        XmlMapper xmlMapper = XmlMapper.xmlBuilder()
                .addModule(new JaxbAnnotationModule())
                .build();

        System.out.println(xmlMapper.readValue(xmlFile, SchoolResponse.class));
    }
}

@Data
@NoArgsConstructor
@ToString
class SchoolResponse {

    @XmlElement(name = "class")
    @JacksonXmlElementWrapper(useWrapping = false)
    private List<ClassRoomResponse> classes;
}


@Data
@NoArgsConstructor
class ClassRoomResponse {

    @XmlAttribute(name = "id")
    private String id;

    @XmlAttribute(name = "num_of_students")
    private String numOfStudents;

    @XmlAttribute(name = "name")
    private String teacherName;

    @XmlElement(name = "schoolYear")
    private String schoolYear;

    @XmlElement(name = "student")
    @JacksonXmlElementWrapper(useWrapping = false)
    private List<Student> students;
}

@Data
@NoArgsConstructor
@ToString
class Student {
    @XmlAttribute(name = "key")
    String key;

    @XmlAttribute(name = "value")
    String value;
}

上面的代码打印：

SchoolResponse(classes=[ClassRoomResponse(id=1, numOfStudents=22, teacherName=Ms Barry, schoolYear=1980, students=[Student(key=202, value=Jim), Student(key=203, value=Tom), Student(key=204, value=Dave)]), ClassRoomResponse(id=2, numOfStudents=20, teacherName=Mr Smith, schoolYear=1981, students=[Student(key=302, value=Jim), Student(key=303, value=Tom), Student(key=304, value=Dave)])])

【讨论】：