Android简单实现 缓存数据

前言

1、每一种要缓存的数据都是有对应的versionCode，通过versionCode请求网络获取是否需要更新
2、提前将要缓存的数据放入assets文件夹中，打包上线。

缓存设计

代码实现

/** * Created by huangbo on 2017/6/19. * * 主要是缓存的工具类 * * 缓存设计： *         0.从内存中读取数据 ：0.1 读取成功-> 取出versionCode ->3 *                             0.2 读取失败-> 1 * *         1.从文件中读取数据：1.1读取成成功-> 取出versionCode ->3 *                             1.2读取失败-> 2 *         2.从Assets中读取数据：2.1读取成功-> 取出versionCode ->3 *                                2.2读取失败-> versionCode==0 ->3 * *         3.用versionCode请求网络 3.1请求成功（有版本更新）将文件写入内存，写入文件； *                                 3.1 请求失败，（没有版本更新） * */public class CacheData {    public static CacheData cacheData;    public static CacheData getInstance() {        if (cacheData == null) {            cacheData = new CacheData();        }        return cacheData;    }    String mFileName;    public CacheData cacheName(String mFileName) {        this.mFileName = mFileName;        return this;    }    ExecutorService cachedThreadPool;    private CacheData() {        cachedThreadPool = Executors.newCachedThreadPool();    }    /**     * 从assets 中读取文件     *     * @return cacheData 的Json串     */    private String readDataFromAssets() {        try {            InputStream ips = AppUtils.ApplicationContext.getAssets().open(mFileName);            byte[] bytes = new byte[ips.available()];            ips.read(bytes);            ips.close();            return new String(bytes);        } catch (IOException e) {            e.printStackTrace();        }        return "";    }    public void readDataFromAssets(final Handler handler) {        cachedThreadPool.execute(new Runnable() {            @Override            public void run() {                String json = readDataFromAssets();                Message message = handler.obtainMessage(1, json);                handler.sendMessage(message);            }        });    }    public void readDataFromFile(final Handler handler) {        cachedThreadPool.execute(new Runnable() {            @Override            public void run() {                Message message = handler.obtainMessage(1, readDataFromFile());                handler.sendMessage(message);            }        });    }    /**     * 将region 更新到指定文件里     * @param     */    public void writeData2FileWithThread(final String Data) {        cachedThreadPool.execute(new Runnable() {            @Override            public void run() {                writeRegion2File(Data);            }        });    }    /**     * @return cacheData 的Json串     */    private String readDataFromFile() {        try {            File file = new File(AppUtils.getCacheDirectory(), mFileName);            if (!file.exists()) {                return null;            }            FileInputStream fis = new FileInputStream(file);            byte[] bytes = new byte[fis.available()];            fis.read(bytes);            fis.close();            return new String(bytes);        } catch (IOException e) {            e.printStackTrace();        }        return "";    }    private void writeData2File(String jsonData) {        try {            File cityFile = new File(AppUtils.getCacheDirectory(), mFileName);            if (!cityFile.exists()) {                cityFile.createNewFile();            }            FileOutputStream fos = new FileOutputStream(cityFile);            fos.write(regionJsonData.getBytes("UTF-8"));            fos.close();        } catch (IOException e) {            e.printStackTrace();        }    }}

使用方法

/** * Created by huangbo on 2017/6/8. */public class Region {    public static Region region;    public static Region getInstance() {        if (region == null) {            region = new Region();        }        return region;    }    ProvinceCityBean provinceCityBean;    public int getVersion() {        return provinceCityBean == null ? 0 : provinceCityBean.getVersion();    }    public ProvinceCityBean getProvinceCityBean() {        return provinceCityBean;    }    public void setProvinceCityBean(final String mRegionJson, final Handler handler) {        if (TextUtils.isEmpty(mRegionJson)) {            return;        }        cachedThreadPool.execute(new Runnable() {            @Override            public void run() {                provinceCityBean = GsonUtils.GsonToBean(mRegionJson, ProvinceCityBean.class);                if (handler != null) {                    handler.sendEmptyMessage(1);                }            }        });    }    ExecutorService cachedThreadPool;    CacheData cacheData;    private Region() {        cachedThreadPool = Executors.newCachedThreadPool();        cacheData = CacheData.getInstance().cacheName(Const.REGION_JSON);    }    /**     * 具体调用方法     */    public void cacheRegion() {        if (provinceCityBean == null) {            readRegionFromFile();        } else {            readRegionFromHttp();        }    }    private void readRegionFromFile() {        cacheData.readDataFromFile(new Handler() {            @Override            public void handleMessage(Message msg) {                String jsonRegion = (String) msg.obj;                onReadRegionFromFileBack(jsonRegion);            }        });    }    /**     * 从文件中读取数据，若为null 继续从Asset中获取     *     * @param jsonRegion     */    private void onReadRegionFromFileBack(String jsonRegion) {        if (!TextUtils.isEmpty(jsonRegion)) {/*文件中读取成功 设置到Region中更新json 取出version请求网络判断是否为最新的版本 */            setProvinceCityBean(jsonRegion, httpHandler);        } else {/*文件中读取失败  从assets 中继续读取*/            cacheData.readDataFromAssets(new Handler() {                @Override                public void handleMessage(Message msg) {                    String jsonRegion = (String) msg.obj;                    onReadRegionFromAssetsBack(jsonRegion);                }            });        }    }    private void onReadRegionFromAssetsBack(String jsonRegion) {        if (!TextUtils.isEmpty(jsonRegion)) {/*从assets中读取成功 设置到Region中更新json*/            setProvinceCityBean(jsonRegion, httpHandler);        } else {            readRegionFromHttp();        }    }    private void readRegionFromHttp() {        ReqRegion reqRegion = new ReqRegion();        reqRegion.sendRequest(false, new OnHttpResult() {            @Override            public void onHttpSuccess(String data) {                setProvinceCityBean(data, null);                cacheData.writeData2FileWithThread(data);            }            @Override            public void onHttpFailure(String message) {            }        });    }    Handler httpHandler = new Handler() {        @Override        public void handleMessage(Message msg) {            super.handleMessage(msg);            readRegionFromHttp();        }    };}

Region.getInstance().cacheRegion();//实现缓存