Android离线缓存的实例代码

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /><uses-permission android:name="android.permission.INTERNET"></uses-permission><uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission><!-- 在SDCard中创建与删除文件权限 --><uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/><!-- 往SDCard写入数据权限 --><uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

if (isNetworkAvailable(MainActivity.this)) {  Toast.makeText(getApplicationContext(), "当前有可用网络！", Toast.LENGTH_LONG).show();} else {  Toast.makeText(getApplicationContext(), "当前wu可用网络！", Toast.LENGTH_LONG).show();}public boolean isNetworkAvailable(Activity activity){  Context context = activity.getApplicationContext();  // 获取手机所有连接管理对象（包括对wi-fi,net等连接的管理）  ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);  if (connectivityManager == null)  {    return false;  }  else  {    // 获取NetworkInfo对象    NetworkInfo[] networkInfo = connectivityManager.getAllNetworkInfo();    if (networkInfo != null && networkInfo.length > 0)    {      for (int i = 0; i < networkInfo.length; i++)      {        System.out.println(i + "===状态===" + networkInfo[i].getState());        System.out.println(i + "===类型===" + networkInfo[i].getTypeName());        // 判断当前网络状态是否为连接状态        if (networkInfo[i].getState() == NetworkInfo.State.CONNECTED)        {          return true;        }      }    }  }  return false;}

  if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){  File sdCardDir = Environment.getExternalStorageDirectory();//获取SDCard目录  File saveFile = new File(sdCardDir, "itcast.txt");  FileOutputStream outStream = new FileOutputStream(saveFile);  outStream.write(result.getBytes());  outStream.close();}

File sdCardDir = Environment.getExternalStorageDirectory();//获取SDCard目录File saveFile1  = new File(sdCardDir, "itcast.txt");BufferedReader br = null;try {  br = new BufferedReader(new FileReader(saveFile1));  String readline = "";  StringBuffer sb = new StringBuffer();  while ((readline = br.readLine()) != null) {    System.out.println("readline:" + readline);    sb.append(readline);  }  String str = sb.toString();

if (isNetworkAvailable(MainActivity.this)) {  Toast.makeText(getApplicationContext(), "当前有可用网络！", Toast.LENGTH_LONG).show();} else {  Toast.makeText(getApplicationContext(), "当前wu可用网络！", Toast.LENGTH_LONG).show();  File sdCardDir = Environment.getExternalStorageDirectory();//获取SDCard目录  File saveFile1  = new File(sdCardDir, "itcast.txt");  BufferedReader br = null;  try {    br = new BufferedReader(new FileReader(saveFile1));    String readline = "";    StringBuffer sb = new StringBuffer();    while ((readline = br.readLine()) != null) {      System.out.println("readline:" + readline);      sb.append(readline);    }    String str = sb.toString();    JSONObject jsonObject = new JSONObject(str);    JSONArray jsonArray = jsonObject.getJSONArray("data");    for (int i = 0; i < jsonArray.length(); i++) {      JSONObject object = jsonArray.getJSONObject(i);      String title = object.getString("name");      String content = object.getString("description");      String url = object.getString("picSmall");      domainBean newsInfo = new domainBean(title, content, url);      //String path = Environment.getExternalStorageDirectory() + "/" + name;      //ObjectOutputStream out =new ObjectOutputStream(new FileOutputStream(path));      //out.writeObject(newsInfo);      list.add(newsInfo);      //新建适配器      beanAdapter = new BeanAdapter(list, MainActivity.this);      //配置适配器      xListView.setAdapter(beanAdapter);      br.close();    }  } catch (IOException e) {    e.printStackTrace();  } catch (JSONException e) {    e.printStackTrace();  }}

 public String logoutPost(String URL){    String result = "";    try {      String data = URLEncoder.encode("UTF-8");// + "&password=" + URLEncoder.encode(password, "UTF-8");//传递的数据      URL url = new URL(URL);//2、url.openConnection()打开网络链接      HttpURLConnection conn = (HttpURLConnection) url.openConnection();//3、设置请求的方式      conn.setRequestMethod("POST");      conn.setDoInput(true);//发送POST请求必须设置允许输出      conn.setDoOutput(true);//发送POST请求必须设置允许输入      conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");      conn.setRequestProperty("Charset", "utf-8");      conn.setRequestProperty("Content-Length", String.valueOf(data.getBytes().length));//5、获取输出流      OutputStream os = conn.getOutputStream();      os.write(data.getBytes());      os.flush();      BufferedReader in=new BufferedReader(new InputStreamReader(conn.getInputStream()));      String line;      while((line=in.readLine())!=null){result+="/n"+line;}            if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){        File sdCardDir = Environment.getExternalStorageDirectory();//获取SDCard目录        File saveFile = new File(sdCardDir, "itcast.txt");        FileOutputStream outStream = new FileOutputStream(saveFile);        outStream.write(result.getBytes());        outStream.close();      }    } catch (UnsupportedEncodingException e) {      e.printStackTrace();    } catch (ProtocolException e) {      e.printStackTrace();    } catch (MalformedURLException e) {      e.printStackTrace();    } catch (IOException e) {      e.printStackTrace();    }    return result;  }