我收到了以下错误信息:
Exception in thread "main" com.google.gson.JsonParseException:
Expecting object found: "com.shagie.app.SimpleMap$Data@24a37368"
当尝试反序列化使用非平凡(non-trivial)键的 Map 时:
package com.shagie.app;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import java.util.HashMap;
public class SimpleMap {
public static void main(String[] args) {
Wrapper w = new Wrapper();
w.m.put(new Data("f", 1), new Data("foo", 3));
w.m.put(new Data("b", 2), new Data("bar", 4));
GsonBuilder gb = new GsonBuilder();
gb.setPrettyPrinting();
Gson g = gb.create();
String json = g.toJson(w);
System.out.println(json);
w = g.fromJson(json, Wrapper.class);
System.out.println(w.m.isEmpty());
}
static public class Wrapper {
HashMap<Data, Data> m = new HashMap<Data, Data>();
}
static public class Data {
String s;
Integer i;
public Data(String arg, Integer val) { s = arg; i = val; }
}
}
这将被序列化为JSON:
{ "m": { "com.shagie.app.SimpleMap$Data@24a37368": { "s": "foo", "i": 3 }, "com.shagie.app.SimpleMap$Data@66edc3a2": { "s": "bar", "i": 4 } } }
可以看到尝试进行序列化的键,但显然无法反序列化。
如何将此对象序列化以便可以进行反序列化?