Java 使用jackson反序列化为自定义对象的HashMap
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();
}
产生的json字符串如下所示:
{ "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字符串反序列化回一个
HashMap<String, Theme>
宾语。
我的反序列化代码如下所示:
HashMap<String, Themes> themes = objectMapperFactory.createObjectMapper().readValue(json, HashMap.class);
它使用正确的键反序列化为HashMap,但不会为这些值创建Theme对象。我不知道在readValue()方法中要指定什么而不是“ HashMap.class”。
任何帮助,将不胜感激。
回答:
你应该创建特定的Map类型并将其提供给反序列化过程:
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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