如何向json文件中寫入數據

先要創建一個寫數據的類：其中Folk是個實體類

class MyJsonWriter {
       ArrayList<Folk> folks;
       File saveFile;
        public MyJsonWriter(ArrayList<Folk> folks){
            this.folks=folks;
        }

        public void setFilePath(String filepath){
            saveFile=new File(filepath);
           try {
                saveFile.createNewFile();
          } catch (IOException e) {

                e.printStackTrace();
           }
        }

       public String getJsonData(){
           String jsonData = null;
    //      String jsonData=new JSONStringer().object().key("village").value("abc").endObject().toString();
            try {
                StringBuilder builder=new StringBuilder();
                ArrayList<String> folksData=new ArrayList<String>();
                JSONArray array=new JSONArray();
               for(int i=0;i<folks.size();i++){
                    Folk folk=folks.get(i);
                    JSONObject jsonObject=new JSONObject();
                    jsonObject.put("name", folk.getName());
                    jsonObject.put("sex", folk.isSex()?"male":"female");
                    jsonObject.put("age", folk.getAge());
                    jsonObject.put("career", folk.getCareer());
                    jsonObject.put("salary", folk.getSalary());
                    folksData.add(jsonObject.toString());
                    array.put(jsonObject);
                }
    //          JSONArray jsonArray=new JSONArray(folksData);
               int len =   array.length();
                jsonData=new JSONStringer().object().key("vallage").value(array).endObject().toString();
                System.out.println(jsonData);
                writeData(jsonData);
            } catch (JSONException e) {

                e.printStackTrace();
            }
            return jsonData;
        }

        private void writeData(String jsonData) {

            try {
                BufferedReader reader=new BufferedReader(new StringReader(jsonData));
                BufferedWriter writer=new BufferedWriter(new FileWriter(saveFile));
                int len=0;
                char[] buffer=new char[1024];
                while((len=reader.read(buffer))!=-1){
                    writer.write(buffer, 0, len);
                }
               writer.flush();
                writer.close();
               reader.close();
            } catch (IOException e) {

                e.printStackTrace();
            }
        }
    }

然後就是真正的寫入工作了，需要起線程的哦···需要的時候調這個方法就可以了。實體類那些是假數據

public void writeData(){
        ArrayList<Folk> floks=new ArrayList<Folk>();
        Folk flok1=new Folk();
        flok1.setAge("10");
        flok1.setCareer("1");
        flok1.setName("flok1");
        flok1.setSalary(1);
        flok1.setSex(true);
        floks.add(flok1);
        Folk flok2=new Folk();
        flok2.setAge("11");
        flok2.setCareer("2");
        flok2.setName("flok2");
        flok2.setSalary(2);
        flok2.setSex(true);
        floks.add(flok2);
        Folk flok3=new Folk();
        flok3.setAge("12");
        flok3.setCareer("3");
        flok3.setName("flok3");
        flok3.setSalary(3);
        flok3.setSex(true);
        floks.add(flok3);
        MyJsonWriter writer=new MyJsonWriter(floks);
        writer.setFilePath(PATH);
        writer.getJsonData();
    }

接下來就是讀json文件中的數據啦：

readbtn.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {

                new Thread() {
                    @Override
                    public void run() {

                        Message msg = handler.obtainMessage();
                        msg.obj = getFileFromSD(PATH);
                        msg.what = 1;
                        handler.sendMessage(msg);
                    }
                }.start();

            }
        });
        }
    private Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            if (msg.what == 1) {
                String result = (String) msg.obj;
                try {
                    JSONObject jObj = new JSONObject(result);
                    tv.setText("people:"+jObj.getString("vallage"));
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }

        }
    };
    private String getFileFromSD(String path) {
        String result = "";

        try {
            FileInputStream f = new FileInputStream(path);
            BufferedReader bis = new BufferedReader(new InputStreamReader(f));
            String line = "";
            while ((line = bis.readLine()) != null) {
                result += line;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;

    }