XStream - com.thoughtworks.xstream.converters.ConversionException答案

【问题标题】：XStream - com.thoughtworks.xstream.converters.ConversionExceptionXStream - com.thoughtworks.xstream.converters.ConversionException
【发布时间】：2018-09-11 04:59:42
【问题描述】：

我正在尝试解析一个 XML 文档，这是文档的结构

    <students>
        <student student_id="1">
            <firstname>Lily</firstname>
            <lastname>Brown</lastname>
            <marks>
                <first>62</first>
                <second>90</second>
                <third>94</third>
                <forth>93</forth>
            </marks>
        </student>
   </students>

但是我收到了这个错误

    Exception in thread "main" com.thoughtworks.xstream.converters.ConversionException: 
    ---- Debugging information ----
    cause-exception     : com.thoughtworks.xstream.mapper.CannotResolveClassException
    cause-message       : firstname
    class               : java.util.ArrayList
    required-type       : java.util.ArrayList
    converter-type      : com.thoughtworks.xstream.converters.collections.CollectionConverter
    path                : /students/student/firstname
    line number         : 4
    class[1]            : xstream$Students
    converter-type[1]   : com.thoughtworks.xstream.converters.reflection.ReflectionConverter
    version             : 1.4.10

有人知道怎么解决吗，下面是类和解析部分

Students.class

@XStreamAlias("students")
public static class Students{
    @XStreamImplicit(itemFieldName = "student")
    public List<Student> student = new ArrayList<Student>();
}

学生班

    @XStreamAlias("student")
    public static class Student {
        String firstname;
        String lastname;
        @XStreamImplicit(itemFieldName = "marks")
        private List<Marks> marks;
        @XStreamAlias("student_id")
        @XStreamAsAttribute  
        int student_id;
    }

Marks.class

@XStreamAlias("marks")
public static class Marks{
    int first;
    int second;
    int third;
    int forth;
}

执行的代码

    FileReader fileReader = new FileReader("src/100.xml");  
    Class<?>[] classes = new Class[] { Students.class, Student.class, Marks.class };
    XStream xstream = new XStream();
    xstream.useAttributeFor(Student.class, "student_id");
    xstream.alias("students", Students.class);
    xstream.alias("student", Student.class);
    xstream.alias("marks", Marks.class);
    XStream.setupDefaultSecurity(xstream);
    xstream.allowTypes(classes);  
    Students students = (Students) xstream.fromXML(fileReader);

非常感谢！

【问题讨论】：

标签： java xml unmarshalling xstream

【解决方案1】：

请在为Student 类中的各个字段添加@XStreamAlias("firstname") 和@XStreamAlias("lastname") 后尝试。

[更新]

好的，有几个变化...

1) 据我了解，您在 Student 中的代码“标记”不是数组，因此请将其更改为在 Student 中键入“标记”。

@XStreamAlias("student")
public class Student {
    String firstname;
    String lastname;

    @XStreamAlias("marks")
    private Marks marks;

    @XStreamAsAttribute
    @XStreamAlias("studentid")
    String student_id;
}

2) 在您的代码中，将 xstream.alias("student", Student.class); 替换为 xstream.addImplicitArray(Students.class, "student", Student.class);

或

试试这段代码来读取xml

        Class<?>[] classes = new Class[] { Students.class, Student.class, Marks.class };
        XStream xstream = new XStream();
        xstream.autodetectAnnotations(true);
        xstream.processAnnotations(Students.class);
        Students students = (Students) xstream.fromXML(xml);

希望有帮助。

【讨论】：