java javax.json：将新的 JsonNumber 添加到现有的 JsonObject
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javax.json: Add new JsonNumber to existing JsonObject
提问by aRestless
I want to add properties to an existing instance of JsonObject. If this property is boolean, this is quite easy:
我想将属性添加到JsonObject. 如果这个属性是boolean，这很容易：
JsonObject jo = ....;
jo.put("booleanProperty", JsonValue.TRUE);
However, I also want to add a JsonNumberbut I couldn't find a way to create an instance of JsonNumber. Here's what I could do:
但是，我也想添加一个，JsonNumber但找不到创建JsonNumber. 这是我可以做的：
JsonObjectBuilder job = Json.createObjectBuilder();
JsonNumber jn = job.add("number", 42).build().getJsonNumber("number");
jo.put("numberProperty", jn);
But I couldn't think of a more dirty way to accomplish my task. So - is there are more direct, cleaner approach to add a JsonNumberto an existing instance of JsonObject?
但我想不出更肮脏的方式来完成我的任务。那么 - 是否有更直接、更简洁的方法来将 a 添加JsonNumber到 的现有实例JsonObject？
回答by aRestless
Okay, I just figured it out myself: You can't.
好吧，我只是自己想通了：你不能。
JsonObjectis supposed to be immutable. Even if JsonObject.put(key, value)exists, at runtime this will throw an UnsupportedOperationException. So if you want to add a key/value-pair to an existing JsonObjectyou'll need something like
JsonObject应该是不可变的。即使JsonObject.put(key, value)存在，在运行时也会抛出一个UnsupportedOperationException. 因此，如果您想将键/值对添加到现有的，JsonObject您将需要类似的东西
private JsonObjectBuilder jsonObjectToBuilder(JsonObject jo) {
JsonObjectBuilder job = Json.createObjectBuilder();
for (Entry<String, JsonValue> entry : jo.entrySet()) {
job.add(entry.getKey(), entry.getValue());
}
return job;
}
and then use it with
然后使用它
JsonObject jo = ...;
jo = jsonObjectToBuilder(jo).add("numberProperty", 42).build();
回答by mark786110
Try using JsonPatch
尝试使用 JsonPatch
String json ="{\"name\":\"John\"}";
JsonObject jo = Json.createReader(new StringReader(json)).readObject();
JsonPatch path = Json.createPatchBuilder()
.add("/last","Doe")
.build();
jo = path.apply(jo);
System.out.println(jo);
回答by Scott Boring
JsonObject is immutable but can be copied into a JsonObjecBuilder using lambdas.
JsonObject 是不可变的，但可以使用 lambda 复制到 JsonObjecBuilder 中。
JsonObject source = ...
JsonObjectBuilder target = Json.createObjectBuilder();
source.forEach(target::add); // copy source into target
target.add("name", "value"); // add or update values
JsonObject destination = target.build(); // build destination
