1.文件储存路径为:/data/data/<包名>/files/
2.文件储存

public void save() {
        String data = "Data to save";
        FileOutputStream out = null;
        BufferedWriter writer = null;
        try {
            //设置文件名称，以及存储方式
            out = openFileOutput("data", Context.MODE_PRIVATE);
            //创建一个OutputStreamWriter对象，传入BufferedWriter的构造器中
            writer = new BufferedWriter(new OutputStreamWriter(out));
            //向文件中写入数据
            writer.write(data);
            
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                writer.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

3.文件读取

   public String load() {
        FileInputStream in = null;
        BufferedReader reader = null;
        StringBuilder content = new StringBuilder();
        try {
            //设置将要打开的存储文件名称
            in = openFileInput("data");
            //FileInputStream -> InputStreamReader ->BufferedReader
            reader = new BufferedReader(new InputStreamReader(in));
            String line = new String();
            //读取每一行数据，并追加到StringBuilder对象中，直到结束
            while ((line = reader.readLine()) != null) {
                content.append(line);
            }

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return content.toString();
    }