3

我正在尝试将以下 xml 反序列化到对象中：

<?xml version="1.0" encoding="iso-8859-1" ?>
   <foo>
     <dean>
      <bar>28</bar>
      <bar>31</bar>
    </dean>
  </foo>

我的课程如下

public class Foo {

private final Dean dean;

public Foo(@JacksonXmlProperty(localName = "dean") final Dean dean) {
    this.dean = dean;
}

public Dean getDean() {
    return dean;
}
}

public class Dean {

@JacksonXmlElementWrapper(useWrapping = false)
private final List<Bar> bar;

public Dean(@JacksonXmlProperty(localName = "bar") final List<Bar> bar) {
    this.bar = bar;
}

public List<Bar> getBar() {
    return bar;
}
}

public class Bar {

@JacksonXmlText
private Integer value;

public Bar(@JacksonXmlProperty(localName = " ") Integer value) {
    this.value = value;
}


public Integer getValue() {
    return value;
}
}

我的映射器依赖项如下：

gradle
ext {
jacksonVersion = "2.8.9"

}

compile(group: "com.fasterxml.jackson.dataformat", name: "jackson-dataformat-
xml", version: "$jacksonVersion")
compile(group: "com.fasterxml.jackson.datatype", name: "jackson-datatype-
jsr310", version: "$jacksonVersion")enter code here

这是 xmlMapper 抛出异常的失败测试

@Test
public void shouldParseAndCreateObject() throws Exception {
    final JacksonXmlModule jacksonXmlModule = new JacksonXmlModule();
     XmlMapper xmlMapper = (XmlMapper) new XmlMapper(jacksonXmlModule)
            .disable(FAIL_ON_UNKNOWN_PROPERTIES, FAIL_ON_IGNORED_PROPERTIES);
    Foo foo = xmlMapper.readValue("<?xml version=\"1.0\" encoding=\"iso-8859-
1\" ?>\n" +
            "<foo>\n" +
            "    <dean>\n" +
            "        <bar>28</bar>\n" +
            "        <bar>31</bar>\n" +
            "    </dean>\n" +
            "</foo>", Foo.class);
    assertThat(foo.getDean().getBar().get(0).getValue(), is(28));
}

com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of Bar: no String-argument constructor/factory method to deserialize from String value ('28')

在 [来源：out/test/resources/test.xml；line: 4, column: 16] (通过引用链: service.Foo["dean"]->service.Dean["bar"]->java.util.ArrayList[0])

从读取异常来看，映射器似乎将值 28 视为字符串而不是整数，但如果我将 Bar 类更改为以下内容并将元素 bar 的属性添加到原始 xml，则相同的测试通过。

public class Bar {

private String test;

@JacksonXmlText
private Integer value;

public Bar(@JacksonXmlProperty(localName = "test", isAttribute = true) String 
test, @JacksonXmlProperty(localName = " ") Integer value) {
    this.test = test;
    this.value = value;
}

public String getTest() {
    return test;
}

public Integer getValue() {
    return value;
}

<?xml version="1.0" encoding="iso-8859-1" ?>
<foo>
<dean>
    <bar test="haha1">28</bar>
    <bar test="haha2">31</bar>
</dean>
</foo>

@Test
public void shouldParseAndCreateObject() throws Exception {
    final JacksonXmlModule jacksonXmlModule = new JacksonXmlModule();
     XmlMapper xmlMapper = (XmlMapper) new XmlMapper(jacksonXmlModule)
            .disable(FAIL_ON_UNKNOWN_PROPERTIES, FAIL_ON_IGNORED_PROPERTIES);
    Foo foo = xmlMapper.readValue("<?xml version=\"1.0\" encoding=\"iso-8859-
1\" ?>\n" +
            "<foo>\n" +
            "    <dean>\n" +
            "        <bar test=\"haha1\">28</bar>\n" +
            "        <bar test=\"haha2\">31</bar>\n" +
            "    </dean>\n" +
            "</foo>" +
            "</foo>", Foo.class);
    assertThat(foo.getDean().getBar().get(0).getValue(), is(28));
}

我会说 Mapper 应该从构造函数参数类型推断类型并尝试使用字符串值实例化该对象，并在后台执行类似 Integer.valueOf("28") 的操作

4

1 回答 1

3

添加到 POJO 空构造函数以及所有字段。还可以尝试以下方法：

JacksonXmlModule module = new JacksonXmlModule();
module.setDefaultUseWrapper(false);
XmlMapper xmlMapper = new XmlMapper(module);
于 2017-12-06T11:50:37.607 回答