What to use to parse json

JSON is a data structure that replaces XML. Compared with xml, it is smaller but has good descriptive capabilities. Because of its compactness, network transmission of data will reduce more traffic and speed up the speed.

This article will introduce three json parsing methods for your reference.

1. JSON parsing: traditional JSON parsing

1. Generate json string

public static String createJsonString(String key, Object value) {
        JSONObject jsonObject = new JSONObject();
        jsonObject.put(key, value);        return jsonObject.toString();
}

2. Parse JSON string

is divided into the following three situations, a JavaBean, a List array, and a List array of nested Maps:

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.json.JSONArray;
import org.json.JSONObject;

import com.android.myjson.domain.Person;

/**
 * 完成对json数据的解析
 * 
 */
public class JsonTools {


    public static Person getPerson(String key, String jsonString) {
        Person person = new Person();
        try {
            JSONObject jsonObject = new JSONObject(jsonString);
            JSONObject personObject = jsonObject.getJSONObject("person");
            person.setId(personObject.getInt("id"));
            person.setName(personObject.getString("name"));
            person.setAddress(personObject.getString("address"));
        } catch (Exception e) {
            // TODO: handle exception
        }
        return person;
    }

    public static List getPersons(String key, String jsonString) {
        List list = new ArrayList();
        try {
            JSONObject jsonObject = new JSONObject(jsonString);
            // 返回json的数组
            JSONArray jsonArray = jsonObject.getJSONArray(key);
            for (int i = 0; i < jsonArray.length(); i++) {
                JSONObject jsonObject2 = jsonArray.getJSONObject(i);
                Person person = new Person();
                person.setId(jsonObject2.getInt("id"));
                person.setName(jsonObject2.getString("name"));
                person.setAddress(jsonObject2.getString("address"));
                list.add(person);
            }
        } catch (Exception e) {
            // TODO: handle exception
        }
        return list;
    }

    public static List getList(String key, String jsonString) {
        List list = new ArrayList();
        try {
            JSONObject jsonObject = new JSONObject(jsonString);
            JSONArray jsonArray = jsonObject.getJSONArray(key);
            for (int i = 0; i < jsonArray.length(); i++) {
                String msg = jsonArray.getString(i);
                list.add(msg);
            }
        } catch (Exception e) {
            // TODO: handle exception
        }
        return list;
    }

    public static List> listKeyMaps(String key,
            String jsonString) {
        List> list = new ArrayList>();
        try {
            JSONObject jsonObject = new JSONObject(jsonString);
            JSONArray jsonArray = jsonObject.getJSONArray(key);
            for (int i = 0; i < jsonArray.length(); i++) {
                JSONObject jsonObject2 = jsonArray.getJSONObject(i);
                Map map = new HashMap();
                Iterator iterator = jsonObject2.keys();
                while (iterator.hasNext()) {
                    String json_key = iterator.next();
                    Object json_value = jsonObject2.get(json_key);
                    if (json_value == null) {
                        json_value = "";
                    }
                    map.put(json_key, json_value);
                }
                list.add(map);
            }
        } catch (Exception e) {
            // TODO: handle exception
        }
        return list;
    }
}

2. JSON parsing GSON

import com.google.gson.Gson;

public class JsonUtils {

    public static String createJsonObject(Object obj) {
        Gson gson = new Gson();
        String str = gson.toJson(obj);
        return str;

    }
}
//二、解析JSON

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

;
public class GsonTools {

    public GsonTools() {
        // TODO Auto-generated constructor stub
    }

    /**
     * @param 
     * @param jsonString
     * @param cls
     * @return
     */
    public static  T getPerson(String jsonString, Class cls) {
        T t = null;
        try {
            Gson gson = new Gson();
            t = gson.fromJson(jsonString, cls);
        } catch (Exception e) {
            // TODO: handle exception
        }
        return t;
    }

    /**
     * 使用Gson进行解析 List
     * 
     * @param 
     * @param jsonString
     * @param cls
     * @return
     */
    public static  List getPersons(String jsonString, Class cls) {
        List list = new ArrayList();
        try {
            Gson gson = new Gson();
            list = gson.fromJson(jsonString, new TypeToken>() {
            }.getType());
        } catch (Exception e) {
        }
        return list;
    }

    /**
     * @param jsonString
     * @return
     */
    public static List getList(String jsonString) {
        List list = new ArrayList();
        try {
            Gson gson = new Gson();
            list = gson.fromJson(jsonString, new TypeToken>() {
            }.getType());
        } catch (Exception e) {
            // TODO: handle exception
        }
        return list;
    }

    public static List> listKeyMaps(String jsonString) {
        List> list = new ArrayList>();
        try {
            Gson gson = new Gson();
            list = gson.fromJson(jsonString,
                    new TypeToken>>() {
                    }.getType());
        } catch (Exception e) {
            // TODO: handle exception
        }
        return list;
    }
}

3. JSON parsing: FastJSON

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.TypeReference;

public class JsonTool {

    public static  T getPerson(String jsonstring, Class cls) {
        T t = null;
        try {
            t = JSON.parseObject(jsonstring, cls);
        } catch (Exception e) {
            // TODO: handle exception
        }
        return t;
    }

    public static  List getPersonList(String jsonstring, Class cls) {
        List list = new ArrayList();
        try {
            list = JSON.parseArray(jsonstring, cls);
        } catch (Exception e) {
            // TODO: handle exception
        }
        return list;
    }

    public static  List> getPersonListMap1(
            String jsonstring) {
        List> list = new ArrayList>();
        try {
            list = JSON.parseObject(jsonstring,
                    new TypeReference>>() {
                    }.getType());

        } catch (Exception e) {
            // TODO: handle exception
        }

        return list;
    }
}

JSON is for mobile devices, especially in poor network environments and traffic restrictions, compared to XML format Data transmission will save traffic and be more efficient. Among these three parsing methods, FastJson is the most efficient and is recommended.

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