[英]Using Gson convert Java object into JsonObject
I have a Java object, and I want to output it as a JSON string. 我有一个Java对象,我想将其输出为JSON字符串。 BUT I want to avoid printing out a property in the Java object. 但我想避免在Java对象中打印出属性。 I know that I could do this using GsonBuilder's excludeFieldsWithoutExposeAnnotation() method. 我知道我可以使用GsonBuilder的excludeFieldsWithoutExposeAnnotation()方法做到这一点。 However, I thought I'd try the alternate approach of removing the property from the JsonObject before printing it out. 但是,我想我会尝试在打印之前从JsonObject中删除属性的替代方法。 The following code works: 以下代码有效:
Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd' 'HH:mm:ss").create();
String javaObjectString = gson.toJson(javaObject);
//javaObjectString currently include "property":"value"
JsonElement jsonElement = gson.toJsonTree(javaObjectString, javaObject.getClass());
JsonObject jsonObject = (JsonObject) jsonElement;
jsonObject.remove("property");
javaObjectString = gson.toJson(jsonObject);
//javaObjectString currently no longer includes "property":"value"
However, it feels a but hacky because I have to output the Java object to a String, and then create a JsonElement from the String, and then cast the JsonElement to a JsonObject. 但是,它感觉很糟糕,因为我必须将Java对象输出到String,然后从String创建一个JsonElement,然后将JsonElement转换为JsonObject。
Is there a more direct way to go from a Java object to a JsonObject? 有没有更直接的方法从Java对象转到JsonObject?
You don't need the intermediary String
. 您不需要中间String
。 Serialize your Java object to a JsonElement
directly with Gson#toJsonTree(Object)
. 使用Gson#toJsonTree(Object)
直接将Java对象序列JsonElement
Gson#toJsonTree(Object)
。 Cast that value to whatever type you expect (JSON object, array, or primitive), perform your removal and invoke its toString()
method to retrieve its JSON representation as a String
. 将该值转换为您期望的任何类型(JSON对象,数组或基元),执行删除并调用其toString()
方法以将其JSON表示形式检索为String
。
For example, 例如,
Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd' 'HH:mm:ss").create();
// JSON data structure
JsonElement jsonElement = gson.toJsonTree(javaObject);
JsonObject jsonObject = (JsonObject) jsonElement;
// property removal
jsonObject.remove("property");
// serialization to String
String javaObjectString = jsonObject.toString();
You can always use the Gson#toJson
overload that accepts a JsonElement
to serialize it directly to a stream if you want to skip that last String
object creation. 如果要跳过最后创建的String
对象,可以始终使用接受JsonElement
的Gson#toJson
重载将其直接序列化为流。
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