使用jackson反序列化为自定义对象的HashMap [英] Deserializing into a HashMap of custom objects with jackson

问题描述

我有以下课程：

import org.codehaus.jackson.annotate.JsonIgnoreProperties;
import org.codehaus.jackson.annotate.JsonProperty;

import java.io.Serializable;
import java.util.HashMap;

@JsonIgnoreProperties(ignoreUnknown = true)
public class Theme implements Serializable {

    @JsonProperty
    private String themeName;

    @JsonProperty
    private boolean customized;

    @JsonProperty
    private HashMap<String, String> descriptor;

    //...getters and setters for the above properties
}

当我执行以下代码时：

    HashMap<String, Theme> test = new HashMap<String, Theme>();
    Theme t1 = new Theme();
    t1.setCustomized(false);
    t1.setThemeName("theme1");
    test.put("theme1", t1);

    Theme t2 = new Theme();
    t2.setCustomized(true);
    t2.setThemeName("theme2");
    t2.setDescriptor(new HashMap<String, String>());
    t2.getDescriptor().put("foo", "one");
    t2.getDescriptor().put("bar", "two");
    test.put("theme2", t2);
    String json = "";
    ObjectMapper mapper = objectMapperFactory.createObjectMapper();
    try {
        json = mapper.writeValueAsString(test);
    } catch (IOException e) {
        e.printStackTrace(); 
    }

生成的json字符串如下所示：

The json string produced looks like this:

{
  "theme2": {
    "themeName": "theme2",
    "customized": true,
    "descriptor": {
      "foo": "one",
       "bar": "two"
    }
  },
  "theme1": {
    "themeName": "theme1",
    "customized": false,
    "descriptor": null
  }
}

我的问题是让上面的json字符串去除serizlize回到

My problem is getting the above json string to de-serizlize back into a

HashMap<String, Theme> 

object。

我的反序列化代码如下所示：

My de-serialization code looks like this:

HashMap<String, Themes> themes =
        objectMapperFactory.createObjectMapper().readValue(json, HashMap.class);

使用正确的密钥对HashMap进行反序列化，但不为值创建Theme对象。我不知道在readValue（）方法中指定了什么而不是HashMap.class。

Which de-serializes into a HashMap with the correct keys, but does not create Theme objects for the values. I don't know what to specify instead of "HashMap.class" in the readValue() method.

任何帮助都将不胜感激。

Any help would be appreciated.

推荐答案

您应该创建特定的Map类型并将其提供给反序列化过程：

You should create specific Map type and provide it into deserialization process:

TypeFactory typeFactory = mapper.getTypeFactory();
MapType mapType = typeFactory.constructMapType(HashMap.class, String.class, Theme.class);
HashMap<String, Theme> map = mapper.readValue(json, mapType);

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