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

Question

我正在尝试解析 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>

但我收到此错误

    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

有谁知道如何修复它，下面是类和解析部分

学生类(class)

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

学生.类(class)

    @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!

Answer 1

请在为Student中的相应字段添加@XStreamAlias("firstname")和@XStreamAlias("lastname")后尝试类。

<小时/>

[已更新]

好的，有一些改变...

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

@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

尝试使用此代码来读取 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。