Java用字符串值替换JsonNode

你的代码有点小问题。添加新文本条目时,必须提供要与新文本节点关联的键值。所以这一行:

nodeObj.set(newNode);

只需要这样:

nodeObj.set("B", newNode);

下面是一个完整的示例,它与您在问题中所展示的完全相同,结合了您提供的代码,只做了以下一个小修复:

public static void main(String... args) throws IOException {

    // Read in the structure provided from a text file
    FileReader f = new FileReader("/tmp/foox.json");
    ObjectMapper mapper = new ObjectMapper();
    JsonNode rootNode = mapper.readTree(f);

    // Print the starting structure
    System.out.println(rootNode);

    // Get the node we want to operate on
    ObjectNode jsonNode = (ObjectNode)rootNode.get(0).get("A");

    // The OPs code, with just the small change of adding the key value when adding the new String
    JsonNode newNode = new TextNode("My String Message");
    ObjectNode nodeObj = (ObjectNode) jsonNode;
    nodeObj.removeAll();
    nodeObj.set("B", newNode);

    // Print the resulting structure
    System.out.println(rootNode);
}

结果是:

[{"A":{"B":{"C":"Message","D":"FN1"}}}]
[{"A":{"B":"My String Message"}}]