如何用另一个（更新）替换 Java Jackson TextNode？
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How can I replace a Java Hymanson TextNode by another one (update)?
提问by yo_haha
My goal is to update some textual fields in a JsonNode.
我的目标是更新 JsonNode 中的一些文本字段。
List<JsonNode> list = json.findValues("fieldName");
for(JsonNode n : list){
// n is a TextNode. I'd like to change its value.
}
I don't see how this could be done. Do you have any suggestion?
我不明白这是怎么做到的。你有什么建议吗？
采纳答案by wassgren
The short answer is: you can't. TextNodedoes not expose any operations that allows you to alter the contents.
简短的回答是：你不能。TextNode不公开任何允许您更改内容的操作。
With that being said, you can easily traverse the nodes in a loop or via recursion to get the desired behaviour. Imagine the following:
话虽如此，您可以轻松地在循环中或通过递归遍历节点以获得所需的行为。想象一下：
public class JsonTest {
public static void change(JsonNode parent, String fieldName, String newValue) {
if (parent.has(fieldName)) {
((ObjectNode) parent).put(fieldName, newValue);
}
// Now, recursively invoke this method on all properties
for (JsonNode child : parent) {
change(child, fieldName, newValue);
}
}
@Test
public static void main(String[] args) throws IOException {
String json = "{ \"fieldName\": \"Some value\", \"nested\" : { \"fieldName\" : \"Some other value\" } }";
ObjectMapper mapper = new ObjectMapper();
final JsonNode tree = mapper.readTree(json);
change(tree, "fieldName", "new value");
System.out.println(tree);
}
}
The output is:
输出是：
{"fieldName":"new value","nested":{"fieldName":"new value"}}
{"fieldName":"new value","nested":{"fieldName":"new value"}}
回答by Harshad Vyawahare
Because you cannot modify a TextNode, you can instead get all the parentNodes of that field, and call the put operation on it with the same field name and a new value. It will replace the existing field and change the value.
因为您无法修改 TextNode，所以您可以获取该字段的所有 parentNode，并使用相同的字段名称和新值对其调用 put 操作。它将替换现有字段并更改值。
List<JsonNode> parentNodes = jsonNode.findParents("fieldName");
if(parentNodes != null) {
for(JsonNode parentNode : parentNodes){
((ObjectNode)parentNode).put("fieldName", "newValue");
}
}
