In Pair.of():你能改变(S先，T后)的名字吗?

Question

{
"first": "1.0",
"second": "Not Predicted"
},
{
"first": "1.1",
"second": "Not Predicted"
}

Pair的表示。其中:配对<S,>of(S first,T second)(所以这里可以先更改默认名称和第二给我们想要保留的东西?

Answer 1

Jackson的解决方案:

为特定类Pair声明序列化器

public static class PairSerializer extends StdSerializer<Pair> {
public PairSerializer() {
this(null);
}
public PairSerializer(Class<Pair> t) {
super(t);
}
@Override
public void serialize(Pair value, JsonGenerator jgen, SerializerProvider provider) throws IOException, JsonProcessingException {
jgen.writeStartObject();
jgen.writeObjectField("a", value.getFirst());   // "a" is replacement for "first"
jgen.writeObjectField("b", value.getSecond());  // "b" is replacement for "second"
jgen.writeEndObject();
}
}

然后注册这个序列化器并将Pair序列化为JSON

ObjectMapper mapper = new ObjectMapper();
SimpleModule module = new SimpleModule();
module.addSerializer(Pair.class, new PairSerializer());
mapper.registerModule(module);
List<Pair<String, String>> pairs = Arrays.asList(Pair.of("1.0", "Unpredicted"), Pair.of("1.1", "Unpredicted"));
System.out.println(mapper.writeValueAsString(pairs));

输出:

[
{
"a": "1.0",
"b": "Unpredicted"
},
{
"a": "1.1",
"b": "Unpredicted"
}
]