Java，如何解析 JSON 进行地理定位？

Question

我正在尝试解析来自的响应 http://maps.googleapis.com/maps/api/geocode/json?latlng=40.183333,44.516667&sensor=true

但总是出现空指针异常，无法获取节点。

这是一个代码

ObjectMapper mapper = new ObjectMapper();
JsonFactory factory = mapper.getJsonFactory(); // since 2.1 use mapper.getFactory() instead
org.codehaus.jackson.JsonParser jp = factory.createJsonParser(json.toString());
JsonNode input = mapper.readTree(jp);
final JsonNode address_components = input.get("results").get("address_components");                        
System.out.println("address_components " + address_components);

for (final JsonNode element : address_components) {
    Iterator<Entry<String, JsonNode>> nodeIterator2 = element.getFields();
    while (nodeIterator2.hasNext()) {
        Map.Entry<String, JsonNode> entry = (Map.Entry<String, JsonNode>) nodeIterator2.next();
        System.out.println(entry.getKey() + " -> " + entry.getValue());
    }
}

如何找到节点？

input.get("results").get("address_components"); or input.get("address_components");

不返回对象。

Answer 1

您需要检索 json 数组并迭代它，

JsonNode resultsArray = input.get("results");
for ( JsonNode node: resultsArray ) {
        System.out.println(node);
}