保存json数据到本地和读取本地json数据

  private void saveJson(JsonBean bean) {
        File file = new File(getFilesDir(), "json.txt");
        BufferedReader br = null;
        String json;
        try {
            br = new BufferedReader(new FileReader(file));
            json = br.readLine();
        } catch (Exception e) {
            e.printStackTrace();
            json = "";
        }
        Gson gson = new Gson();
        ArrayList<ProductDetailBean> productList = new ArrayList<>();
        if (!"".equals(json)) {
            Type type = new TypeToken<ArrayList<ProductDetailBean>>(){}.getType();
            productList = gson.fromJson(json, type);
        }
        int index = -1;
        for (int i = 0; i < productList.size(); i++) {
            ProductDetailBean productDetailBean = productList.get(i);
            int id = productDetailBean.product.id;
            if (id == bean.product.id) {
                index = i;
                break;
            }
        }
        if (index != -1) {
            productList.remove(index);
        }
        productList.add(bean);
        String newJson = gson.toJson(productList);
        FileOutputStream fos = null;
        try {
            fos = new FileOutputStream(file);
            fos.write(newJson.getBytes());
            fos.flush();
        } catch (Exception e) {
            e.printStackTrace();
        }
        if (br != null) {
            try {
                br.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (fos != null) {
            try {
                fos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

 读取本地json数据如下:

ArrayList<JsonBean> jsonList = new ArrayList<>();
 private void geJson() {
        File file = new File(getFilesDir(), "json.txt");
        BufferedReader br = null;
        String json;
        try {
            br = new BufferedReader(new FileReader(file));
            json = br.readLine();
        } catch (Exception e) {
            e.printStackTrace();
            json = "";
        }
        Gson gson = new Gson();

        if (!"".equals(json)) {
            Type type = new TypeToken<ArrayList<JsonBean>>() {
            }.getType();
            jsonList = gson.fromJson(json, type);
            Collections.reverse(jsonList);
            mAdapter = new MyAdapter();
            lvList.setAdapter(mAdapter);
        }

        if (br != null) {
            try {
                br.close();

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

    }