Java 当@JacksonXmlProperty.localName与@JacksonXmlRootElement.localName匹配时，无法反序列化展开的列表

好吧，朋友们。。。我很难在这件事上下定决心。我有一个XML文档，表示类型

XmlTest

XmlTest

具有类型为

List

的属性

children

children

是一个未包装的XML集合

问题是，当我将XML源反序列化为

XmlTest

实例时，它会失败：

以下是我正在使用的XML文档：

---

如果您编写自定义反序列化程序，则可以正常工作

package api.core.jasper;

import java.io.IOException;
import java.util.List;

import org.junit.Test;

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.JsonToken;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import com.fasterxml.jackson.databind.deser.std.StdDeserializer;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;
import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlElementWrapper;
import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty;
import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlRootElement;
import com.google.common.base.Objects;
import com.google.common.base.Optional;
import com.google.common.collect.Lists;

public class UnitTest {

  @Test
  public void test() throws Exception {
    final ObjectMapper mapper = new XmlMapper();

    final XmlTest before =
        new XmlTest("0", Lists.newArrayList(new XmlTest("0.1", null),
            new XmlTest("0.2", Lists.newArrayList(new XmlTest("0.2.1", null)))));
    System.out.println(before);
    final String xml = mapper.writeValueAsString(before);
    System.out.println(xml);
    final XmlTest after = mapper.readValue(xml, XmlTest.class);
    System.out.println(after);
  }

  @JsonDeserialize(using = XmlTestDeserializer.class)
  @JacksonXmlRootElement(localName = "test")
  public static class XmlTest {
    @JacksonXmlProperty(localName = "id", isAttribute = true)
    public String id;

    @JacksonXmlElementWrapper(useWrapping = false)
    @JacksonXmlProperty(localName = "test")
    public List<XmlTest> children;

    public XmlTest(final String id, final List<XmlTest> children) {
      this.id = id;
      this.children = Optional.fromNullable(children).or(Lists.<XmlTest>newArrayList());
    }

    @Override
    public String toString() {
      return Objects.toStringHelper(this)
          .add("id", id)
          .add("children", children)
          .toString();
    }
  }

  public static class XmlTestDeserializer extends StdDeserializer<XmlTest> {

    protected XmlTestDeserializer() {
      super(XmlTest.class);
    }

    @Override
    public XmlTest deserialize(final JsonParser jp, final DeserializationContext ctxt) throws IOException,
        JsonProcessingException {
      if (jp.getCurrentToken() != JsonToken.START_OBJECT) {
        throw new IOException("Invalid token, expected START_OBJECT");
      }

      String id = null;
      final List<XmlTest> children = Lists.newArrayList();

      while (jp.nextToken() != JsonToken.END_OBJECT) {
        final String key = jp.getCurrentName();
        jp.nextToken();

        if ("id".equals(key)) {
          id = jp.readValueAs(String.class);
        } else if ("test".equals(key)) {
          final XmlTest child = jp.readValueAs(XmlTest.class);
          if (child != null) {
            children.add(child);
          }
        }
      }

      jp.close();

      return new XmlTest(id, children);
    }
  }
}

包api.core.jasper；
导入java.io.IOException；
导入java.util.List；
导入org.junit.Test；
导入com.fasterxml.jackson.core.JsonParser；
导入com.fasterxml.jackson.core.JsonProcessingException；
导入com.fasterxml.jackson.core.JsonToken；
导入com.fasterxml.jackson.databind.DeserializationContext；
导入com.fasterxml.jackson.databind.ObjectMapper；
导入com.fasterxml.jackson.databind.annotation.JsonDeserialize；
导入com.fasterxml.jackson.databind.desr.std.StdDeserializer；
导入com.fasterxml.jackson.dataformat.xml.XmlMapper；
导入com.fasterxml.jackson.dataformat.xml.annotation.jacksonxmlementwrapper；
导入com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty；
导入com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlRootElement；
导入com.google.common.base.Objects；
导入com.google.common.base.Optional；
导入com.google.common.collect.list；
公共类单元测试{
@试验
public void test（）引发异常{
final ObjectMapper mapper=new XmlMapper（）；
前的最终测试=
新的XmlTest（“0”，列出.newArrayList（新的XmlTest（“0.1”，空），
新的XmlTest（“0.2”，Lists.newArrayList（新的XmlTest（“0.2.1”，null‘）’）；
系统输出打印项次（之前）；
最后一个字符串xml=mapper.writeValueAsString（之前）；
System.out.println（xml）；
final XmlTest after=mapper.readValue（xml，XmlTest.class）；
系统输出打印项次（后）；
}
@JsonDeserialize（使用=XmlTestDeserializer.class）
@JacksonXmlRootElement（localName=“test”）
公共静态类XmlTest{
@JacksonXmlProperty（localName=“id”，isAttribute=true）
公共字符串id；
@JacksonXmlElementWrapper（useWrapping=false）
@JacksonXmlProperty（localName=“test”）
公开儿童名单；
公共XmlTest（最终字符串id，最终列表子项）{
this.id=id；
this.children=可选.fromNullable（children）.或（Lists.newArrayList（））；
}
@凌驾
公共字符串toString（）{
返回Objects.toStringHelper（this）
.add（“id”，id）
.添加（“儿童”，儿童）
.toString（）；
}
}
公共静态类XmlTestDeserializer扩展StdDeserializer{
受保护的XmlTestDeserializer（）{
super（XmlTest.class）；
}
@凌驾
公共XmlTest反序列化（最终JsonParser jp，最终反序列化上下文ctxt）引发IOException，
JsonProcessingException{
if（jp.getCurrentToken（）！=JsonToken.START\u对象）{
抛出新IOException（“无效令牌，应为START_对象”）；
}
字符串id=null；
final List children=Lists.newArrayList（）；
while（jp.nextToken（）！=JsonToken.END\u对象）{
最终字符串键=jp.getCurrentName（）；
jp.nextToken（）；
如果（“id”。等于（键））{
id=jp.readValueAs（String.class）；
}否则，如果（“测试”。等于（键））{
最终XmlTest子级=jp.readValueAs（XmlTest.class）；
if（child！=null）{
添加（child）；
}
}
}
jp.close（）；
返回新的XmlTest（id，children）；
}
}
}

测试控制台输出：

XmlTest{id=0, children=[XmlTest{id=0.1, children=[]}, XmlTest{id=0.2, children=[XmlTest{id=0.2.1, children=[]}]}]}
<test id="0"><test id="0.1"/><test id="0.2"><test id="0.2.1"/></test></test>
XmlTest{id=0, children=[XmlTest{id=0.1, children=[]}, XmlTest{id=0.2, children=[XmlTest{id=0.2.1, children=[]}]}]}

XmlTest{id=0，children=[XmlTest{id=0.1，children=[]}，XmlTest{id=0.2，children=[XmlTest{id=0.2.1，children=[]}]
XmlTest{id=0，children=[XmlTest{id=0.1，children=[]}，XmlTest{id=0.2，children=[XmlTest{id=0.2.1，children=[]}]}

我已尝试使用您的示例代码。看起来像是jackson数据格式xml中的一个bug。@EugeneEvdokimov，我同意我今天提交了这个bug

package api.core.jasper;

import static org.junit.Assert.fail;

import java.util.List;

import org.junit.Test;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;
import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlElementWrapper;
import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty;
import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlRootElement;
import com.google.common.collect.Lists;

public class UnitTest {

  @Test
  public void test() throws Exception {
    final ObjectMapper mapper = new XmlMapper();

    final XmlTest before =
        new XmlTest("0", Lists.newArrayList(new XmlTest("0.1", null),
            new XmlTest("0.2", Lists.newArrayList(new XmlTest("0.2.1", null)))));
    final String xml = mapper.writeValueAsString(before);
    final XmlTest after = mapper.readValue(xml, XmlTest.class);

    fail();
  }

  @JacksonXmlRootElement(localName = "test")
  public static class XmlTest {
    private final String id;
    private final List<XmlTest> children;

    @JsonCreator
    public XmlTest(@JsonProperty("id") final String id, @JsonProperty("tests") final List<XmlTest> children) {
      this.id = id;
      this.children = children;
    }

    @JsonProperty("id")
    @JacksonXmlProperty(localName = "id", isAttribute = true)
    public String id() {
      return id;
    }

    @JsonProperty("children")
    @JacksonXmlElementWrapper(useWrapping = false)
    @JacksonXmlProperty(localName = "test")
    public List<XmlTest> children() {
      return children;
    }
  }

}

<root id="0">
    <test id="0.1">
        <test id="0.1.1" />
    </test>
    <test id="0.2" />
    <test id="0.3">
        <test id="0.3.1" />
    </test>
</root>

package api.core.jasper;

import java.io.IOException;
import java.util.List;

import org.junit.Test;

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.JsonToken;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import com.fasterxml.jackson.databind.deser.std.StdDeserializer;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;
import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlElementWrapper;
import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty;
import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlRootElement;
import com.google.common.base.Objects;
import com.google.common.base.Optional;
import com.google.common.collect.Lists;

public class UnitTest {

  @Test
  public void test() throws Exception {
    final ObjectMapper mapper = new XmlMapper();

    final XmlTest before =
        new XmlTest("0", Lists.newArrayList(new XmlTest("0.1", null),
            new XmlTest("0.2", Lists.newArrayList(new XmlTest("0.2.1", null)))));
    System.out.println(before);
    final String xml = mapper.writeValueAsString(before);
    System.out.println(xml);
    final XmlTest after = mapper.readValue(xml, XmlTest.class);
    System.out.println(after);
  }

  @JsonDeserialize(using = XmlTestDeserializer.class)
  @JacksonXmlRootElement(localName = "test")
  public static class XmlTest {
    @JacksonXmlProperty(localName = "id", isAttribute = true)
    public String id;

    @JacksonXmlElementWrapper(useWrapping = false)
    @JacksonXmlProperty(localName = "test")
    public List<XmlTest> children;

    public XmlTest(final String id, final List<XmlTest> children) {
      this.id = id;
      this.children = Optional.fromNullable(children).or(Lists.<XmlTest>newArrayList());
    }

    @Override
    public String toString() {
      return Objects.toStringHelper(this)
          .add("id", id)
          .add("children", children)
          .toString();
    }
  }

  public static class XmlTestDeserializer extends StdDeserializer<XmlTest> {

    protected XmlTestDeserializer() {
      super(XmlTest.class);
    }

    @Override
    public XmlTest deserialize(final JsonParser jp, final DeserializationContext ctxt) throws IOException,
        JsonProcessingException {
      if (jp.getCurrentToken() != JsonToken.START_OBJECT) {
        throw new IOException("Invalid token, expected START_OBJECT");
      }

      String id = null;
      final List<XmlTest> children = Lists.newArrayList();

      while (jp.nextToken() != JsonToken.END_OBJECT) {
        final String key = jp.getCurrentName();
        jp.nextToken();

        if ("id".equals(key)) {
          id = jp.readValueAs(String.class);
        } else if ("test".equals(key)) {
          final XmlTest child = jp.readValueAs(XmlTest.class);
          if (child != null) {
            children.add(child);
          }
        }
      }

      jp.close();

      return new XmlTest(id, children);
    }
  }
}

XmlTest{id=0, children=[XmlTest{id=0.1, children=[]}, XmlTest{id=0.2, children=[XmlTest{id=0.2.1, children=[]}]}]}
<test id="0"><test id="0.1"/><test id="0.2"><test id="0.2.1"/></test></test>
XmlTest{id=0, children=[XmlTest{id=0.1, children=[]}, XmlTest{id=0.2, children=[XmlTest{id=0.2.1, children=[]}]}]}