Json操作（汇总）

利用：com.fasterxml.jackson

原文地址：https://blog.csdn.net/joyous/article/details/9448461

说明：Map转化为Json；创建Json，添加节点或Array

原文地址：https://www.cnblogs.com/winner-0715/p/6109225.html

说明：Java对象转化为Json

原文地址：http://neverflyaway.iteye.com/blog/2299805

说明：读写Json文件，遍历JsonNode数组

原文地址：https://blog.csdn.net/u014452858/article/details/45650817

说明：jsonGenerator

原文地址：https://blog.csdn.net/jay_1989/article/details/51262059

说明：两种生成Json的方法。方法一：一个个结点创建。方法二：拼接字符串创建。

【方法一】生成Json

    package com.pcmall;  

    import com.fasterxml.jackson.databind.ObjectMapper;
    import com.fasterxml.jackson.databind.node.ArrayNode;
    import com.fasterxml.jackson.databind.node.ObjectNode;  

    public class CreateJson {
        /**
         * 创建一个 json，并向该 json 添加内容
         */
        public static void MyTest04()
        {
          try
          {
            ObjectMapper mapper = new ObjectMapper();
            ObjectNode root1 = mapper.createObjectNode();    

            root1.put("nodekey1", 1);
            root1.put("nodekey2", 2);    

            System.out.println(root1.toString());    

          //Create the root node
            ObjectNode root = mapper.createObjectNode ();
            //Create a child node
            ObjectNode node1 = mapper.createObjectNode ();
            node1.put ("nodekey1", 1);
            node1.put ("nodekey2", 2);
            //Bind the child nodes
            root.put ("child", node1);
            //Array of nodes
            ArrayNode arrayNode = mapper.createArrayNode ();
            arrayNode.add (node1);
            arrayNode.add (1);
            //Bind array node
            root.put ("arraynode", arrayNode);    

            System.out.println (mapper.writeValueAsString (root));
            // 得到的输出信息
            // {"child":{"nodekey1":1,"nodekey2":2},"arraynode":[{"nodekey1":1,"nodekey2":2},1]}
          }
          catch (Exception e)
          {    

          }
        }    

        public static void main(String[] args){
            MyTest04();
        }
    }  

输出结果：

{
    "child": {
        "nodekey1": 1,
        "nodekey2": 2
    },
    "arraynode": [{
        "nodekey1": 1,
        "nodekey2": 2
    },
    1]
}

【方法二】生成Json

String str = "{\"data\":{\"hasnext\":0,\"info\":[{\"id\":\"288206077664983\",\"timestamp\":1371052476},{\"id\":\"186983078111768\",\"timestamp\":1370944068},{\"id\":\"297031120529307\",\"timestamp\":1370751789},{\"id\":\"273831022294863\",\"timestamp\":1369994812}],\"timestamp\":1374562897,\"totalnum\":422},\"errcode\":0,\"msg\":\"ok\",\"ret\":0,\"seqid\":5903702688915195270}";
        ObjectMapper mapper = new ObjectMapper();
        try {
            JsonNode root = mapper.readTree(str);
            System.out.println("root" + root.toString());
        } catch (IOException e) {
            e.printStackTrace();
        }  

输出结果：

root {
    "data": {
        "hasnext": 0,
        "info": [{
            "id": "288206077664983",
            "timestamp": 1371052476
        },
        {
            "id": "186983078111768",
            "timestamp": 1370944068
        },
        {
            "id": "297031120529307",
            "timestamp": 1370751789
        },
        {
            "id": "273831022294863",
            "timestamp": 1369994812
        }],
        "timestamp": 1374562897,
        "totalnum": 422
    },
    "errcode": 0,
    "msg": "ok",
    "ret": 0,
    "seqid": 5903702688915195270
}