[英]Jackson: how to convert flat json into nested json
How can I convert a json string like 我如何转换一个JSON字符串像
{
"a.b": 1,
"a.c.d": 2
}
into json string 转换成json字符串
{
"a": {
"b": 1,
"c": {
"d": 2
}
}
}
by using ObjectMapper
? 通过使用
ObjectMapper
?
The easiest option is to create custom deserializer or custom been with @JsonAnySetter
and @JsonAnyGetter
Here is example: 最简单的选择是创建自定义解串器或使用
@JsonAnySetter
和@JsonAnyGetter
自定义这是示例:
public static final String json = "{\"a.b\": 1,\"a.c.d\": 2}";
public static void main(String[] args) throws IOException {
ObjectMapper mapper = new ObjectMapper();
HelperBean bean = mapper.readValue(json, HelperBean.class);
System.out.println(mapper.writeValueAsString(bean));
// result: {"a":{"b":1,"c":{"d":2}}}
}
public static class HelperBean{
@JsonIgnore
private Map<String, Object> data = new TreeMap<>();
@JsonAnySetter
public void setDays(String key, Object value){
String[] parts = key.split("\\.");
Map<String, Object> currMap = data;
for (int i = 0; i< parts.length; i++){
String part = parts[i];
Object subMap = currMap.get(part);
if (i == parts.length - 1) // last node
currMap.put(part, value);
else if(subMap == null){ // new node
subMap = new TreeMap<>();
currMap.put(part, subMap);
currMap = (Map<String, Object>) subMap;
}else if (subMap instanceof Map){ // existing node
currMap.put(part, subMap);
currMap = (Map<String, Object>) subMap;
} else { // node conflict
// handle exception when a.b = 1 and a.b.c = 1
}
}
}
@JsonAnyGetter
public Map<String, Object> getData() {
return data;
}
}
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