java json解析（转）

转自：https://www.cnblogs.com/sunnywindycloudy/p/8343013.html

给服务端发送请求后，服务端会返回一连串的数据，这些数据在大部分情况下都是XML格式或者JSON格式。然后JSON相对XML来说解析相对方便一些，所以先说说JSON的解析。

JSON的基本数据格式有这几种：

1.一个JSON对象——JSONObject

{"name":"胡小威" , "age":20 , "male":true}

2.一个JSON数组——JSONArray

[{"name":"胡小威" , "age":20 , "male":true},{"name":"赵小亮" , "age":22 , "male":false}]

3.复杂一点的JSONObject

{"name":"胡小威", "age"=20, "male":true, "address":{"street":"岳麓山南", "city":"长沙","country":"中国"}}

4.复杂一点的JSONArray

[

{"name":"胡小威", "age"=20, "male":true, "address":{"street":"岳麓山南", "city":"长沙","country":"中国"}},

{"name":"赵小亮", "age"=22, "male":false, "address":{"street":"九州港", "city":"珠海","country":"中国"}}

]

5.来个更复杂的，这是我从爱帮公交上扒取的数据

{"buses":{"bus":[{"last_foot_dist":"0","time":"37","segments":{"segment":[{"line_name":"立珊专线(中南大学学生公寓-长沙火车站)","foot_dist":"362","stat_xys":"","stats":"岳麓山南;湖南师大;二里半;岳麓山北;市四医院;华图教育(太平街口);牛耳教育(南阳街口);韭菜园;曙光路口;长岛路口;长沙火车站","end_stat":"长沙火车站","line_xys":"","line_dist":"7535","start_stat":"岳麓山南"}]},"foot_dist":"362","dist":"7897"},{"last_foot_dist":"0","time":"41","segments":{"segment":[{"line_name":"旅1路(科教新村-长沙火车站)","foot_dist":"337","stat_xys":"","stats":"岳麓山南;湖南师大;二里半;岳麓山北;市四医院;华图教育(太平街口);蔡锷中路口;韭菜园;乔庄;曙光路口;长岛路口;五一东村;车站路口;长沙火车站","end_stat":"长沙火车站","line_xys":"","line_dist":"7822","start_stat":"岳麓山南"}]},"foot_dist":"337","dist":"8159"}]}}

接下来是解析部分

一、直接解析

1.{"name":"胡小威" , "age":20 , "male":true}

public void parseJsonObject(String json) {
        try {
            JSONObject jsonObject = new JSONObject(json);
            String name = jsonObject.getString("name");
            int age = jsonObject.getInt("age");
            boolean male = jsonObject.getBoolean("male");
            //接下来该干嘛干嘛
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }  

2.[{"name":"胡小威" , "age":20 , "male":true},{"name":"赵小亮" , "age":22 , "male":false}]

public void parseJSONArray(String json) {
        try {
            JSONArray jsonArray = new JSONArray(json);
            for (int i = 0; i < jsonArray.length(); i++) {
                jsonObject = jsonArray.getJSONObject(i);
                String name = jsonObject.getString("name");
                int age = jsonObject.getInt("age");
                boolean male = jsonObject.getBoolean("male");
                //接下来该干嘛干嘛
            }
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }  

3.{"name":"胡小威", "age"=20, "male":true, "address":{"street":"岳麓山南", "city":"长沙","country":"中国"}}

public void parseJsonPerson(String json) {
        try {
            JSONObject jsonObject = new JSONObject(json);
            String name = jsonObject.getString("name");
            int age = jsonObject.getInt("age");
            boolean male = jsonObject.getBoolean("male");
            JSONObject addressJSON = jsonObject.getJSONObject("address");
            String street = addressJSON.getString("street");
            String city = addressJSON.getString("city");
            String country = addressJSON.getString("country");
            Address address = new Address(street, city, country);
            Person person = new Person(name, age, male, address);
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }  

4.

[

{"name":"胡小威", "age"=20, "male":true, "address":{"street":"岳麓山南", "city":"长沙","country":"中国"}},

{"name":"赵小亮", "age"=22, "male":false, "address":{"street":"九州港", "city":"珠海","country":"中国"}}

]

public void parseJsonArrayPerson(String json) {
        List<Person> persons = new ArrayList<Person>();
        try {
            jsonArray = new JSONArray(json);
            for (int i = 0; i < jsonArray.length(); i++) {
                jsonObject = jsonArray.getJSONObject(i);
                String name = jsonObject.getString("name");
                int age = jsonObject.getInt("age");
                boolean male = jsonObject.getBoolean("male");
                JSONObject addressJSON = jsonObject.getJSONObject("address");
                String street = addressJSON.getString("street");
                String city = addressJSON.getString("city");
                String country = addressJSON.getString("country");
                Address address = new Address(street, city, country);
                Person person = new Person(name, age, male, address);
                persons.add(person);
                Log.v("juno", person.toString());
            }
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        Log.v("juno", persons.toString());
    }  

5. {"buses":{"bus":[{"last_foot_dist":"0","time":"37","segments":{"segment":[{"line_name":"立珊专线(中南大学学生公寓-长沙火车站)","foot_dist":"362","stat_xys":"","stats":"岳麓山南;湖南师大;二里半;岳麓山北;市四医院;华图教育(太平街口);牛耳教育(南阳街口);韭菜园;曙光路口;长岛路口;长沙火车站","end_stat":"长沙火车站","line_xys":"","line_dist":"7535","start_stat":"岳麓山南"}]},"foot_dist":"362","dist":"7897"},{"last_foot_dist":"0","time":"41","segments":{"segment":[{"line_name":"旅1路(科教新村-长沙火车站)","foot_dist":"337","stat_xys":"","stats":"岳麓山南;湖南师大;二里半;岳麓山北;市四医院;华图教育(太平街口);蔡锷中路口;韭菜园;乔庄;曙光路口;长岛路口;五一东村;车站路口;长沙火车站","end_stat":"长沙火车站","line_xys":"","line_dist":"7822","start_stat":"岳麓山南"}]},"foot_dist":"337","dist":"8159"}]}}

public List<Salution> parseJSON(String str){
        Log.d("返回的JSON数据：", str);
        List<Salution> busList = new ArrayList<Salution>();  

        try {
            JSONObject jsonObject = new JSONObject(str);
            JSONObject busesJSON = jsonObject.getJSONObject("buses");
            JSONArray busJSArray=busesJSON.getJSONArray("bus");
            for(int i=0;i<busJSArray.length();i++){
                JSONObject busJSObject = busJSArray.getJSONObject(i);
                JSONObject segsJSObject=busJSObject.getJSONObject("segments");
                JSONArray segJSArray=segsJSObject.getJSONArray("segment");
                    Salution st=new Salution();  

                    for(int j=0;j<segJSArray.length();j++){
                        if(j==0){
                            JSONObject segJSObject = segJSArray.getJSONObject(j);
                            st.setLine_name1(segJSObject.getString("line_name"));
                            Log.d("line_name", segJSObject.getString("line_name"));
                            st.setStats1(segJSObject.getString("stats"));
                            st.setEnd_stat1(segJSObject.getString("end_stat"));
                            st.setStart_stat1(segJSObject.getString("start_stat"));
                        }
                        if(j==1){
                            JSONObject segJSObject = segJSArray.getJSONObject(j);
                            st.setLine_name2(segJSObject.getString("line_name"));
                            Log.d("line_name", segJSObject.getString("line_name"));
                            st.setStats2(segJSObject.getString("stats"));
                            st.setEnd_stat2(segJSObject.getString("end_stat"));
                            st.setStart_stat2(segJSObject.getString("start_stat"));
                        }
                    }  

                    busList.add(st);
            }
            return busList;
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }  

这里我只是简单获取了几个我想要的数据。

二、使用JSON类库Gson 来解析JSON

Gson 是 Google 提供的用来在 Java 对象和 JSON 数据之间进行映射的 Java 类库。可以将一个 JSON 字符串转成一个 Java 对象，或者反过来。

首先，从 code.google.com/p/google-gson/downloads/list下载GsonAPI

google-gson-1.7.1-release.zip

再把gson-1.7.jar copy到libs

可以使用两种方法解析

①、通过获取JsonReader对象解析JSON数据：

String jsonData = "[{\"username\":\"arthinking\",\"userId\":001},{\"username\":\"Jason\",\"userId\":002}]";
try{
    JsonReader reader = new JsonReader(new StringReader(jsonData));
    reader.beginArray();
    while(reader.hasNext()){
        reader.beginObject();
        while(reader.hasNext()){
            String tagName = reader.nextName();
            if(tagName.equals("username")){
                System.out.println(reader.nextString());
            }
            else if(tagName.equals("userId")){
                System.out.println(reader.nextString());
            }
        }
        reader.endObject();
    }
    reader.endArray();
}
catch(Exception e){
    e.printStackTrace();
}  

②、通过把JSON数据映射成一个对象，使用Gson对象的fromJson()方法获取一个对象数组进行操作

Type listType = new TypeToken<LinkedList<User>>(){}.getType();
Gson gson = new Gson();
LinkedList<User> users = gson.fromJson(jsonData, listType);
for (Iterator iterator = users.iterator(); iterator.hasNext();) {
    User user = (User) iterator.next();
    System.out.println(user.getUsername());
    System.out.println(user.getUserId());
}