java 使用java访问嵌套的JSON对象值
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Access nested JSON object value using java
提问by user2436651
{
"files": {
"f1.png": {
"intext": "A",
"inval": 0,
"inbinary": false
},
"f2.png": {
"intext": "A",
"inval": 0,
"inbinary": true
}
}
}
How to access value of inval when the f1.png value is not fixed. i.e. the name of file can be anything, its not known so how can I access value for inval field for various files in this JSON using Java?
当 f1.png 值不固定时如何访问 inval 的值。即文件的名称可以是任何东西，它是未知的，那么如何使用 Java 访问此 JSON 中各种文件的 inval 字段的值？
回答by Pritesh Shah
Please try below code,
请尝试以下代码，
import org.json.JSONException;
import org.json.JSONObject;
public static void main(String[] args) {
String jsonString = "{\"files\": {\"f1.png\": {\"intext\": \"A\",\"inval\": 0,\"inbinary\": false}, \"f2.png\": {\"intext\": \"A\",\"inval\": 0,\"inbinary\": true}}}";
try {
JSONObject jsonObject =new JSONObject(jsonString);
JSONObject jsonChildObject = (JSONObject)jsonObject.get("files");
Iterator iterator = jsonChildObject.keys();
String key = null;
while(iterator.hasNext()){
key = (String)iterator.next();
System.out.println("inval value: "+((JSONObject)jsonChildObject.get(key)).get("inval"));
}
}
catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Hope it solves your issue
希望它能解决你的问题
回答by fge
Using Hymansonand JsonNode, you'd do:
使用Hymanson和JsonNode，你会这样做：
private static final ObjectReader READER = new ObjectMapper()
.getReader;
// blah
// read the node
final JsonNode node = READER.readTree(fromWhatever);
// access the inner "files" member
final JsonNode filesNode = node.get("files");
to access the inner object.
访问内部对象。
Then to walk the filesNodeobject you'd do:
然后走filesNode你要做的对象：
final Iterator<Map.Entry<String, JsonNode>> iterator = filesNode.fields();
Map.Entry<String, JsonNode> entry;
while (iterator.hasNext()) {
entry = iterator.next();
// the "inval" field is entry.getValue().get("inval")
}
If you can use this projectthis becomes more simple:
如果您可以使用此项目，这将变得更加简单：
// or .fromFile(), .fromReader(), others
final JsonNode node = JsonLoader.fromString(whatever);
final Map<String, JsonNode> map = HymansonUtils.nodeToMap(node.get("files"));
// walk the map
回答by best wishes
You can use JsonPath library to access child elements. https://github.com/json-path/JsonPath
您可以使用 JsonPath 库来访问子元素。 https://github.com/json-path/JsonPath
It can be as simple as
它可以很简单
List<String> names = JsonPath.read(json, "$.files.*);
With some modifications.
经过一些修改。
回答by Jabongg
for nested array type,
对于嵌套数组类型，
{
"combo": [
{"field":"divisions"},
{"field":"lob"}
]
} below code will help.
下面的代码会有所帮助。
Iterator<?> keys = jsnObj.keys();
while(keys.hasNext()) {
String key = (String) keys.next();
JSONArray list = (JSONArray) jsnObj.get(key);
if(list==null || list.length()==0)
return null;
List<String> comboList = new ArrayList<String>();
for(int i=0;i<list.length();i++){
JSONObject jsonObject = (JSONObject)list.get(i);
if(jsonObject==null)
continue;
comboList.add((String)jsonObject.get("fields"));
}
}
