android对象缓存,Android简单实现 缓存数据
前言
1、每一種要緩存的數據都是有對應的versionCode，通過versionCode請求網絡獲取是否需要更新
2、提前將要緩存的數據放入assets文件夾中，打包上線。
緩存設計
代碼實現
/**
* Created by huangbo on 2017/6/19.
*
* 主要是緩存的工具類
*
* 緩存設計：
* 0.從內存中讀取數據 ：0.1 讀取成功-> 取出versionCode ->3
* 0.2 讀取失敗-> 1
*
* 1.從文件中讀取數據：1.1讀取成成功-> 取出versionCode ->3
* 1.2讀取失敗-> 2
* 2.從Assets中讀取數據：2.1讀取成功-> 取出versionCode ->3
* 2.2讀取失敗-> versionCode==0 ->3
*
* 3.用versionCode請求網絡 3.1請求成功(有版本更新)將文件寫入內存，寫入文件；
* 3.1 請求失敗，(沒有版本更新)
*
*/
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();
}
/**
* 從assets 中讀取文件
*
* @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);
}
});
}
/**
* 將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);
}
/**
* 具體調用方法
*/
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);
}
});
}
/**
* 從文件中讀取數據，若為null 繼續從Asset中獲取
*
* @param jsonRegion
*/
private void onReadRegionFromFileBack(String jsonRegion) {
if (!TextUtils.isEmpty(jsonRegion)) {/*文件中讀取成功 設置到Region中更新json 取出version請求網絡判斷是否為最新的版本 */
setProvinceCityBean(jsonRegion, httpHandler);
} else {/*文件中讀取失敗 從assets 中繼續讀取*/
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)) {/*從assets中讀取成功 設置到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();//實現緩存
以上為個人經驗，希望能給大家一個參考，也希望大家多多支持腳本之家。如有錯誤或未考慮完全的地方，望不吝賜教。
總結
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