Android简单实现 缓存数据
作者：huagbo
这篇文章主要介绍了Android简单实现 缓存数据,小编觉得挺不错的，现在分享给大家，也给大家做个参考。一起跟随小编过来看看吧
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
以上为个人经验，希望能给大家一个参考，也希望大家多多支持脚本之家。如有错误或未考虑完全的地方，望不吝赐教。