Question

我正在使用杰克逊并且能够获得JSONObject。我需要能够将此JSONObject转换为json形式。含义，由此JSONObject的子字符串表示的对象。

类似的东西：

JsonObject object = ...;
object.toJsonString();

一个简单的谷歌搜索令人惊讶地没有发现很多回复，我无法看到如何自己做。

有什么想法吗？

Answer 1

尝试，

JSONObject object = ...;
ObjectMapper mapper = new ObjectMapper();
String jsonString = mapper.writeValueAsString(object);

Answer 2

  StringWriter out = new StringWriter();
  object.writeJSONString(out);

  String jsonText = out.toString();
  System.out.print(jsonText);

Answer 3

如果需要桥接两个API，则可以创建自定义StdSerializer。有关自定义序列化器的更多信息： https://www.baeldung.com/jackson-custom-serialization

private static class JSONObjectSerializer extends StdSerializer<JSONObject> {

    JSONObjectSerializer(){
        this(null);
    }

    JSONObjectSerializer(Class<JSONObject> t) {
        super(t);
    }

    @Override public void serialize(JSONObject value, JsonGenerator gen, SerializerProvider provider) throws IOException {
        gen.writeStartObject();
        value.keys().forEachRemaining(key-> {
            try {
                gen.writeStringField(key,value.getString(key));
            } catch (IOException ex){
                throw new RuntimeException("Encountered an error serializing the JSONObject.",ex);
            }
        });
        gen.writeEndObject();
    }

    private static SimpleModule toModule(){
        return new SimpleModule().addSerializer(JSONObject.class, new JSONObjectSerializer());
    }
}

//.......

ObjectWriter writer = new ObjectMapper()
    .registerModule(JSONObjectSerializer.toModule())
    .writerWithDefaultPrettyPrinter();

//.......

try {
    s = w.writeValueAsString(v);// v being your JSONObject or parent
} catch (JsonProcessingException ex) {
    throw new RuntimeException("Unable to write object to json.", ex);
}

用Jackson将JsonObject转换为Json String

3 个答案: