android 云端数据库更新到本地

1. 服务器端存放一个sqlite数据库
2. 服务器端存放一个json文件或者写一个接口（更新时间）
3. 本地sdcard存放一个txt记录更新时间
4. app启动首先获取服务器端json文件中的更新时间，然后读取本地txt中更新时间
5. 若本地时间早于服务器端时间，则下载服务器端数据库
6. 下载完成连接并查询将数据插入本地数据库；
7. 数据更新之后将更新时间写入本地txt

下面贴代码

请求接口对比时间

 OkHttpUtils.get()
                .url(StringUtil.DANCE_DB_VERSION_PATH)
                .build()
                .execute(new StringCallback() {
                    @Override
                    public void onError(Call call, Response response, Exception e, int id) {

                    }

                    @Override
                    public void onResponse(String response, int id) {
                        JSONObject jsonObject = null;
                        try {
                            jsonObject = new JSONObject(response);
                            final String dbUpdateTime = jsonObject.optString("update_time");
                            Log.d("[dbUpdateTime]", "onResponse: " + dbUpdateTime);
                            if (!dbUpdateTime.equals("")) {
                                final String currentDbDateStr = readSDFile("mnt/sdcard/dbDacesUpdateDataTime.txt");
                                if (currentDbDateStr != null && !currentDbDateStr.equals("")) {
                                    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
                                    try {
                                        Date currentDate = sdf.parse(currentDbDateStr);
                                        Date networkDate = sdf.parse(dbUpdateTime);
                                        if (networkDate.after(currentDate)) {
                                            new Thread(new Runnable() {
                                                @Override
                                                public void run() {
                                                    downloadNewDb(currentDbDateStr, dbUpdateTime);
                                                }
                                            }).start();


                                        }
                                    } catch (ParseException e) {
                                    }
                                }
                            }
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                });

下载数据库

   private void downloadNewDb(String currentDbDateStr, String dbUpdateTime) {
        String downloadStr = StringUtil.DANCES_INFO_PATH;
        String newSongPath = StringUtil.CURRENT_NEW_DANCES_PATH;
        File nFile = new File(newSongPath);
        if (nFile.exists()) {
            nFile.delete();
        }
        HttpURLConnection httpURLConnection = null;
        RandomAccessFile raf = null;
        InputStream is = null;
        try {
            URL url = new URL(downloadStr);
            httpURLConnection = (HttpURLConnection) url.openConnection();
            httpURLConnection.setConnectTimeout(5000);
            httpURLConnection.setReadTimeout(5000);
            httpURLConnection.setDoOutput(true);
            httpURLConnection.setRequestMethod("GET");
            int code = httpURLConnection.getResponseCode();
            if (code == 200) {
                int length = httpURLConnection.getContentLength();
                is = httpURLConnection.getInputStream();
                raf = new RandomAccessFile(nFile, "rw");
                raf.seek(0);
                int len = 0;
                long totalSize = 0;
                byte[] buffer = new byte[1024];
                while ((len = is.read(buffer)) != -1) {
                    totalSize = totalSize + len;
                    raf.write(buffer, 0, len);
                }
                danceUpdate(currentDbDateStr, dbUpdateTime);
            }
        } catch (Exception e) {
            Log.d("[Exception]", "downloadNewDb: " + e.toString());
        } finally {
            try {
                if (is != null) {
                    is.close();
                }
                if (raf != null) {
                    raf.close();
                }
            } catch (Exception e2) {
            }
        }
    }

读取本地TXT时间

   private String readSDFile(String fileName) {
        try {
            File file = new File(fileName);
            if (!file.exists()) {
                writeSDFile(fileName, "2018-10-01");
                return "2018-10-01";
            } else {
                FileInputStream fis = new FileInputStream(file);
                int length = fis.available();
                byte[] buffer = new byte[length];
                fis.read(buffer);
                String res = EncodingUtils.getString(buffer, "UTF-8");
                fis.close();
                return res;
            }
        } catch (IOException e) {
            e.printStackTrace();
            return "";
        }

    }

写入本地TXT时间

  private void writeSDFile(String fileName, String write_str) {
        try {
            File file = new File(fileName);
            FileOutputStream fos = new FileOutputStream(file);
            byte[] bytes = write_str.getBytes();
            fos.write(bytes);
            fos.close();
        } catch (Exception e) {
        }
    }

数据查询和插入

 private void danceUpdate(String currentDbDateStr, String dbUpdateTime) {
        List<Dances> updateDaceList = dbDancesUpdateUtil.getUpdateDance(currentDbDateStr);
        dbDancesUpdateUtil.insertUpdatedance(updateDaceList);
        writeSDFile("mnt/sdcard/dbDacesUpdateDataTime.txt", dbUpdateTime);
    }