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
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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
}
}
我的问题是将上面的 json 字符串反序列化为一个
My problem is getting the above json string to de-serizlize back into a
HashMap<String, Theme>
对象.
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);
使用正确的键反序列化为 HashMap,但不为值创建 Theme 对象.我不知道在 readValue() 方法中指定什么来代替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.
任何帮助将不胜感激.
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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