JSON解析(Android原生技术)

Android的API提供了将json格式的字符串{}转换成Java对象

• JSONObject(String json) : 将json字符串解析为json对象
• Xxx getXxx(String name) : 根据name, 在json对象中得到对应的Value
• Xxx optXxx(String name) : 根据name, 在json对象中得到对应的Value

注意：optXxx方法会在对应的key中的值不存在的时候返回一个空字符串或者返回你指定的默认值，但是getString方法会出现空指针异常的错误。

将json格式的字符串[]转换为Java对象的List

• JSONArray(String json) : 将json字符串解析为json数组
• int length() : 得到json数组中元素的个数
• Xxx getXxx(int index) : 根据下标得到json数组中对应的元素数据
• Xxx optXxx(int index) : 根据下标得到json数组中对应的元素数据

Demo展示:

    // (4)特殊json数据解析,键值是数字字符串
    //特殊的json数据解析不能用GsonFormat工具生成对象类，只能自己写对象类
    private void jsonToJavaOfSpecial() {

        // 1 获取或创建JSON数据
        String json = "{\n" +
                "    \"code\": 0,\n" +
                "    \"list\": {\n" +
                "        \"0\": {\n" +
                "            \"aid\": \"6008965\",\n" +
                "            \"author\": \"哔哩哔哩番剧\",\n" +
                "            \"coins\": 170,\n" +
                "            \"copyright\": \"Copy\",\n" +
                "            \"create\": \"2016-08-25 21:34\"\n" +
                "        },\n" +
                "        \"1\": {\n" +
                "            \"aid\": \"6008938\",\n" +
                "            \"author\": \"哔哩哔哩番剧\",\n" +
                "            \"coins\": 404,\n" +
                "            \"copyright\": \"Copy\",\n" +
                "            \"create\": \"2016-08-25 21:33\"\n" +
                "        }\n" +
                "    }\n" +
                "}";
       //格式的形成：先打双引号，然后将json格式的字符串张贴到双引号里面，会自动生成上述格式

        // 创建封装的Java对象
        FilmInfo filmInfo = new FilmInfo();

        // 2 解析json
        try {
            JSONObject jsonObject = new JSONObject(json);

            // 第一层解析
            int code = jsonObject.optInt("code");
            JSONObject list = jsonObject.optJSONObject("list");

            // 第一层封装
            filmInfo.setCode(code);
            List<FilmInfo.FilmBean> lists = new ArrayList<>();
            filmInfo.setList(lists);

            // 第二层解析
            for (int i = 0; i < list.length(); i++) {
                JSONObject jsonObject1 = list.optJSONObject(i + "");
                
                if(jsonObject1 != null) {
                    String aid = jsonObject1.optString("aid");

                    String author = jsonObject1.optString("author");

                    int coins = jsonObject1.optInt("coins");

                    String copyright = jsonObject1.optString("copyright");

                    String create = jsonObject1.optString("create");

                    // 第二层数据封装
                    FilmInfo.FilmBean filmBean = new FilmInfo.FilmBean();
                    filmBean.setAid(aid);
                    filmBean.setAuthor(author);
                    filmBean.setCoins(coins);
                    filmBean.setCopyright(copyright);
                    filmBean.setCreate(create);

                    lists.add(filmBean);
                }
            }

        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    // (3)复杂json数据解析
    private void jsonToJavaOfComplex() {

        // 1 获取或创建JSON数据
        String json = "{\n" +
                "    \"data\": {\n" +
                "        \"count\": 5,\n" +
                "        \"items\": [\n" +
                "            {\n" +
                "                \"id\": 45,\n" +
                "                \"title\": \"坚果\"\n" +
                "            },\n" +
                "            {\n" +
                "                \"id\": 132,\n" +
                "                \"title\": \"炒货\"\n" +
                "            },\n" +
                "            {\n" +
                "                \"id\": 166,\n" +
                "                \"title\": \"蜜饯\"\n" +
                "            },\n" +
                "            {\n" +
                "                \"id\": 195,\n" +
                "                \"title\": \"果脯\"\n" +
                "            },\n" +
                "            {\n" +
                "                \"id\": 196,\n" +
                "                \"title\": \"礼盒\"\n" +
                "            }\n" +
                "        ]\n" +
                "    },\n" +
                "    \"rs_code\": \"1000\",\n" +
                "    \"rs_msg\": \"success\"\n" +
                "}";

        // 封装Java对象
        DataInfo dataInfo = new DataInfo();

        // 2 解析json
        try {
            JSONObject jsonObject = new JSONObject(json);

            // 第一层解析
            JSONObject data = jsonObject.optJSONObject("data");
            String rs_code = jsonObject.optString("rs_code");
            String rs_msg = jsonObject.optString("rs_msg");

            // 第一层封装
            dataInfo.setRs_code(rs_code);
            dataInfo.setRs_msg(rs_msg);
            DataInfo.DataBean dataBean = new DataInfo.DataBean();
            dataInfo.setData(dataBean);

            // 第二层解析
            int count = data.optInt("count");
            JSONArray items = data.optJSONArray("items");

            // 第二层数据的封装
            dataBean.setCount(count);

            List<DataInfo.DataBean.ItemsBean> itemsBean = new ArrayList<>();
            dataBean.setItems(itemsBean);

            // 第三层解析
            for (int i = 0; i < items.length(); i++) {
                JSONObject jsonObject1 = items.optJSONObject(i);

                if (jsonObject1 != null) {
                    int id = jsonObject1.optInt("id");

                    String title = jsonObject1.optString("title");

                    // 第三层数据的封装
                    DataInfo.DataBean.ItemsBean bean = new DataInfo.DataBean.ItemsBean();
                    bean.setId(id);
                    bean.setTitle(title);

                    itemsBean.add(bean);
                }
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }


    // (2)将json格式的字符串[]转换为Java对象的List
    private void jsonToJavaListByNative() {

        // 1 获取或创建JSON数据
        String json = "[\n" +
                "    {\n" +
                "        \"id\": 1,\n" +
                "        \"imagePath\": \"http://192.168.10.165:8080/f1.jpg\",\n" +
                "        \"name\": \"大虾1\",\n" +
                "        \"price\": 12.3\n" +
                "    },\n" +
                "    {\n" +
                "        \"id\": 2,\n" +
                "        \"imagePath\": \"http://192.168.10.165:8080/f2.jpg\",\n" +
                "        \"name\": \"大虾2\",\n" +
                "        \"price\": 12.5\n" +
                "    }\n" +
                "]";

        List<ShopInfo> shops = new ArrayList<>();

        // 2 解析json
        try {
            JSONArray jsonArray = new JSONArray(json);

            for (int i = 0; i < jsonArray.length(); i++) {
                JSONObject jsonObject = jsonArray.getJSONObject(i);

                if (jsonObject != null) {
                    int id = jsonObject.optInt("id");

                    String name = jsonObject.optString("name");

                    double price = jsonObject.optDouble("price");

                    String imagePath = jsonObject.optString("imagePath");

                    // 封装Java对象
                    ShopInfo shopInfo = new ShopInfo(id, name, price, imagePath);

                    shops.add(shopInfo);
                }
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }


    // (1)将json格式的字符串{}转换为Java对象
    private void jsonToJavaObjectByNative() {

        // 1 获取或创建JSON数据
        String json = "{\n" +
                "\t\"id\":2, \"name\":\"大虾\", \n" +
                "\t\"price\":12.3, \n" +
                "\t\"imagePath\":\"http://192.168.10.165:8080/L05_Server/images/f1.jpg\"\n" +
                "}\n";

        ShopInfo shopInfo = null;

        // 2 解析json
        try {
            JSONObject jsonObject = new JSONObject(json);
//            int id = jsonObject.getInt("id");
            int id1 = jsonObject.optInt("id");

            String name = jsonObject.optString("name");

            double price = jsonObject.optDouble("price");

            String imagePath = jsonObject.optString("imagePath");

            // 封装Java对象
            shopInfo = new ShopInfo(id1, name, price, imagePath);

        } catch (JSONException e) {
            e.printStackTrace();
        }
    }
}

JAVA对象类:

import java.util.List;

public class DataInfo {
    private DataBean data;
    private String rs_code;
    private String rs_msg;

    @Override
    public String toString() {
        return "DataInfo{" +
                "data=" + data +
                ", rs_code='" + rs_code + '\'' +
                ", rs_msg='" + rs_msg + '\'' +
                '}';
    }

    public DataBean getData() {
        return data;
    }

    public void setData(DataBean data) {
        this.data = data;
    }

    public String getRs_code() {
        return rs_code;
    }

    public void setRs_code(String rs_code) {
        this.rs_code = rs_code;
    }

    public String getRs_msg() {
        return rs_msg;
    }

    public void setRs_msg(String rs_msg) {
        this.rs_msg = rs_msg;
    }

   //类中还有类，说明该json格式的数据中对象里面包含对象
    public static class DataBean {
        private int count;
        private List<ItemsBean> items;

        @Override
        public String toString() {
            return "DataBean{" +
                    "count=" + count +
                    ", items=" + items +
                    '}';
        }
        public int getCount() {
            return count;
        }
        public void setCount(int count) {
            this.count = count;
        }
        public List<ItemsBean> getItems() {
            return items;
        }
        public void setItems(List<ItemsBean> items) {
            this.items = items;
        }

        public static class ItemsBean {
            private int id;
            private String title;

            @Override
            public String toString() {
                return "ItemsBean{" +
                        "id=" + id +
                        ", title='" + title + '\'' +
                        '}';
            }
            public int getId() {
                return id;
            }
            public void setId(int id) {
                this.id = id;
            }
            public String getTitle() {
                return title;
            }
            public void setTitle(String title) {
                this.title = title;
            }
        }
    }
}

public class ShopInfo {
    private int id;
    private String name;
    private double price;
    private String imagePath;

    public ShopInfo(int id, String name, double price, String imagePath) {
        this.id = id;
        this.name = name;
        this.price = price;
        this.imagePath = imagePath;
    }

    public ShopInfo() {
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public String getImagePath() {
        return imagePath;
    }

    public void setImagePath(String imagePath) {
        this.imagePath = imagePath;
    }

    @Override
    public String toString() {
        return "ShopInfo{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", price=" + price +
                ", imagePath='" + imagePath + '\'' +
                '}';
    }
}

import java.util.List;

public class FilmInfo {

    private int code;
    private List<FilmBean> list;

    @Override
    public String toString() {
        return "FilmInfo{" +
                "code=" + code +
                ", list=" + list +
                '}';
    }

    public int getCode() {
        return code;
    }

    public void setCode(int code) {
        this.code = code;
    }

    public List<FilmBean> getList() {
        return list;
    }

    public void setList(List<FilmBean> list) {
        this.list = list;
    }

    public static class FilmBean{
        private String aid;
        private String author;
        private int coins;
        private String copyright;
        private String create;

        @Override
        public String toString() {
            return "FilmBean{" +
                    "aid='" + aid + '\'' +
                    ", author='" + author + '\'' +
                    ", coins=" + coins +
                    ", copyright='" + copyright + '\'' +
                    ", create='" + create + '\'' +
                    '}';
        }

        public String getAid() {
            return aid;
        }

        public void setAid(String aid) {
            this.aid = aid;
        }

        public String getAuthor() {
            return author;
        }

        public void setAuthor(String author) {
            this.author = author;
        }

        public int getCoins() {
            return coins;
        }

        public void setCoins(int coins) {
            this.coins = coins;
        }

        public String getCopyright() {
            return copyright;
        }

        public void setCopyright(String copyright) {
            this.copyright = copyright;
        }

        public String getCreate() {
            return create;
        }

        public void setCreate(String create) {
            this.create = create;
        }
    }
}