Java 读取 Json格式的 内容

一、Json 报文格式如下：

二、获取 Json 报文中字段的内容

 import java.io.IOException;
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;

 public class ReadJsonValue_1_00_001 {

     public static void main(String args[]) {

         String test = "{\n" +
             "  \"results\":\n" +
             "  [\n" +
             "    {\n" +
             "      \"objectID\":\"357\",\n" +
             "      \"geoPoints\":\n" +
             "      [\n" +
             "        {\n" +
             "          \"x\":504604.59802246094,\n" +
             "          \"y\":305569.9150390625\n" +
             "        }\n" +
             "      ]\n" +
             "    },\n" +
             "    {\n" +
             "      \"objectID\":\"358\",\n" +
             "      \"geoPoints\":\n" +
             "      [\n" +
             "        {\n" +
             "          \"x\":504602.2680053711,\n" +
             "          \"y\":305554.43603515625\n" +
             "        }\n" +
             "      ]\n" +
             "    }\n" +
             "  ]\n" +
             "}\n";

         System.out.println( test );

         ObjectMapper mapper = new ObjectMapper();
         JsonNode node = null;
         try {
             node = mapper.readTree( test );
         } catch (JsonProcessingException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         }

         //将Json串以树状结构读入内存
         JsonNode results = node.get("results");//得到results这个节点下的信息
         System.out.println( "results.size() = " + results.size() );

         for(int i = 0; i < results.size(); i++ ) //遍历results下的信息，size()函数可以得节点所包含的的信息的个数，类似于数组的长度
         {
             System.out.println( results.get(i).get("objectID").textValue() ); //读取节点下的某个子节点的值

             JsonNode geoNumber = results.get(i).get("geoPoints");
             System.out.println( "geoNumber() = " + geoNumber.size() );
             for(int j = 0; j < geoNumber.size(); j++ )   //循环遍历子节点下的信息
             {
                 System.out.println(geoNumber.get(j).get("x").doubleValue()+"--"+geoNumber.get(j).get("y").doubleValue());
             }
         }
     }

 }

三、读取结果为