上下文中，存储内部存储器，并从中读取

你好，我有一个productLookup(productId, Contexto)行的上下文有问题，我不明白。上下文中，存储内部存储器，并从中读取

我想要做的是当我通过网络从数据库中获取数据时，我还希望将对象的ID传递给productLookup函数以下载关联的jpg并将其保存在内部存储器。不知道是否是最好的为什么要这样做。如果你们有任何建议，请不要犹豫，让我知道它！

package com.example.proyectoprueba; 

import java.io.File; 
import java.io.FileInputStream; 
import java.io.FileNotFoundException; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.InputStream; 
import java.net.URL; 
import java.util.ArrayList; 
import java.util.HashMap; 

import org.json.JSONArray; 
import org.json.JSONException; 
import org.json.JSONObject; 

import android.app.ProgressDialog; 
import android.content.Context; 
import android.content.Intent; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.os.Bundle; 
import android.support.v7.app.ActionBarActivity; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.widget.ListAdapter; 
import android.widget.ListView; 
import android.widget.SimpleAdapter; 
import android.widget.Toast; 

import com.google.gson.Gson; 
import com.google.gson.GsonBuilder; 
import com.loopj.android.http.AsyncHttpClient; 
import com.loopj.android.http.AsyncHttpResponseHandler; 
import com.loopj.android.http.RequestParams; 

public class prueba extends ActionBarActivity{ 

// DB Class to perform DB related operations 
DBController controller = new DBController(this); 
// Progress Dialog Object 
ProgressDialog prgDialog; 
HashMap<String, String> queryValues; 

@Override 
protected void onCreate(Bundle savedInstanceState){ 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.lista); 

    ArrayList<HashMap<String, String>> platoList = controller.getAllPlatos(); 
    // If users exists in SQLite DB 
    if (platoList.size() != 0) { 
     // Set the User Array list in ListView 
     ListAdapter adapter = new SimpleAdapter(prueba.this, platoList, R.layout.itemlista, new String[] { 
         "platoId", "platoNombre", "platoDescripcion", "platoPrecio" }, new int[] { R.id.codigo, R.id.nombre, R.id.descripcion, R.id.precio }); 
     ListView myList = (ListView) findViewById(R.id.listaplatos); 
     myList.setAdapter(adapter); 
    } 

// Initialize Progress Dialog properties 
    prgDialog = new ProgressDialog(this); 
    prgDialog.setMessage("Transferring Data from Remote MySQL DB and Syncing SQLite. Please wait..."); 
    prgDialog.setCancelable(false); 

} 

@Override 
public boolean onCreateOptionsMenu(Menu menu) { 

    // Inflate the menu; this adds items to the action bar if it is present. 
    getMenuInflater().inflate(R.menu.main, menu); 
    return true; 
} 
public boolean onOptionsItemSelected(MenuItem item) { 

    Intent intent; 
    switch (item.getItemId()){ 
    case R.id.entremeses: 
     intent =new Intent(this,prueba.class); 
     this.startActivity(intent); 
     break; 
    case R.id.arrocesypasta: 
     intent=new Intent(this,prueba.class); 
     this.startActivity(intent); 
     break; 
    case R.id.bebidas: 
     intent=new Intent(this,prueba.class); 
     this.startActivity(intent); 
     break; 
    case R.id.refresh: 
//    Transfer data from remote MySQL DB to SQLite on Android and perform Sync 

      syncSQLiteMySQLDB(); 
      return true; 

    } 


    return super.onOptionsItemSelected(item); 
} 



// Method to Sync MySQL to SQLite DB 
public void syncSQLiteMySQLDB() { 
    // Create AsycHttpClient object 
    AsyncHttpClient client = new AsyncHttpClient(); 
    // Http Request Params Object 
    RequestParams params = new RequestParams(); 
    // Show ProgressBar 
    prgDialog.show(); 
    // Make Http call to getusers.php 
    client.post("http://restaurantechinaimperial.com/mysqlsqlitesync/getplatos.php", params, new AsyncHttpResponseHandler() { 
      @Override 
      public void onSuccess(String response) { 
       // Hide ProgressBar 
       prgDialog.hide(); 
       // Update SQLite DB with response sent by getusers.php 
       updateSQLite(response); 
      } 
      // When error occured 
      @Override 
      public void onFailure(int statusCode, Throwable error, String content) { 
       // TODO Auto-generated method stub 
       // Hide ProgressBar 
       prgDialog.hide(); 
       if (statusCode == 404) { 
        Toast.makeText(getApplicationContext(), "Requested resource not found", Toast.LENGTH_LONG).show(); 
       } else if (statusCode == 500) { 
        Toast.makeText(getApplicationContext(), "Something went wrong at server end", Toast.LENGTH_LONG).show(); 
       } else { 
        Toast.makeText(getApplicationContext(), "Unexpected Error occcured! [Most common Error: Device might not be connected to Internet]", 
          Toast.LENGTH_LONG).show(); 
       } 
      } 
    }); 
} 

public void updateSQLite(String response){ 
    ArrayList<HashMap<String, String>> platosynclist; 
    platosynclist = new ArrayList<HashMap<String, String>>(); 
    // Create GSON object 
    Gson gson = new GsonBuilder().create(); 
    try { 
     // Extract JSON array from the response 
     JSONArray arr = new JSONArray(response); 
     System.out.println(arr.length()); 
     // If no of array elements is not zero 
     if(arr.length() != 0){ 
      // Loop through each array element, get JSON object which has userid and username 
      for (int i = 0; i < arr.length(); i++) { 
       // Get JSON object 
       JSONObject obj = (JSONObject) arr.get(i); 
       System.out.println(obj.get("platoId")); 
       System.out.println(obj.get("platoNombre")); 
       System.out.println(obj.get("platoDescripcion")); 
       System.out.println(obj.get("platoCategoria")); 
       System.out.println(obj.get("platoCaracteristicas")); 
       System.out.println(obj.get("platoPrecio")); 
       // DB QueryValues Object to insert into SQLite 
       queryValues = new HashMap<String, String>(); 
       // Add userID extracted from Object 
       queryValues.put("platoId", obj.get("platoId").toString()); 
       // Add userName extracted from Object 
       queryValues.put("platoNombre", obj.get("platoNombre").toString()); 
      // Add userID extracted from Object 
       queryValues.put("platoDescripcion", obj.get("platoDescripcion").toString()); 
       // Add userName extracted from Object 
       queryValues.put("platoCategoria", obj.get("platoCategoria").toString()); 
      // Add userID extracted from Object 
       queryValues.put("platoCaracteristicas", obj.get("platoCaracteristicas").toString()); 
       // Add userName extracted from Object 
       queryValues.put("platoPrecio", obj.get("platoPrecio").toString()); 
       // Insert Plato into SQLite DB 
       controller.insertPlato(queryValues); 
       HashMap<String, String> map = new HashMap<String, String>(); 
       // Add status for each plato in Hashmap 
       map.put("Id", obj.get("platoId").toString()); 
       map.put("status", "1"); 
//I made the call here... it's right they why I did it? 
        platosynclist.add(map); 
        String productId=map.get("platoId"); 
        try { 
         productLookup(productId); 
        } catch (IOException e) { 
         e.printStackTrace(); 
        } 
       } 


     // Inform Remote MySQL DB about the completion of Sync activity by passing Sync status of Users 
      updateMySQLSyncSts(gson.toJson(platosynclist)); 
      // Reload the Main Activity 
      reloadActivity(); 
     } 
    } catch (JSONException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 
} 

// Method to inform remote MySQL DB about completion of Sync activity 
public void updateMySQLSyncSts(String json) { 
    System.out.println(json); 
    AsyncHttpClient client = new AsyncHttpClient(); 
    RequestParams params = new RequestParams(); 
    params.put("syncsts", json); 
    // Make Http call to updatesyncsts.php with JSON parameter which has Sync statuses of Users 
    client.post("http://restaurantechinaimperial.com/mysqlsqlitesync/updatesyncstsplatos.php", params, new AsyncHttpResponseHandler() { 
     @Override 
     public void onSuccess(String response) { 
      Toast.makeText(getApplicationContext(), "MySQL DB has been informed about Sync activity", Toast.LENGTH_LONG).show(); 
     } 

     @Override 
     public void onFailure(int statusCode, Throwable error, String content) { 
       Toast.makeText(getApplicationContext(), "Error Occured", Toast.LENGTH_LONG).show(); 
     } 
    }); 
}

//下载图片

public String productLookup(String productID) throws IOException{ 


    URL url = new URL("http://www.restaurantechinaimperial.com/menufotos/" + productID + ".jpg"); 

    InputStream input = null; 
    FileOutputStream output = null; 

    try { 
     String outputName = productID + "-thumbnail.jpg"; 

     input = url.openConnection().getInputStream(); 
     output = getApplicationContext().openFileOutput(outputName, Context.MODE_PRIVATE); 

     int read; 
     byte[] data = new byte[1024]; 
     while ((read = input.read(data)) != -1) 
      output.write(data, 0, read); 

     return outputName; 

    } finally { 
     if (output != null) 
      output.close(); 
     if (input != null) 
      input.close(); 
    } 
} 

public Bitmap decodeFile(File f){ 
    try { 
     //decode image size 
     BitmapFactory.Options o = new BitmapFactory.Options(); 
     o.inJustDecodeBounds = true; 
     BitmapFactory.decodeStream(new FileInputStream(f),null,o);  
     int scale=1; 
     //decode with inSampleSize 
     BitmapFactory.Options o2 = new BitmapFactory.Options(); 
     o2.inSampleSize=scale; 
     return BitmapFactory.decodeStream(new FileInputStream(f), null, o2); 
    } catch (FileNotFoundException e) {} 
    return null; 
}

我的另一个问题是如何读取存储的图像，在我有一个列表视图对话框添加。我想我必须使用 getFileStreamPath（filename）; FileInputStream fi = new FileInputStream（filePath）;

但是不确定。还有来自其他活动

// If users exists in SQLite DB 
     if (platoList.size() != 0) { 
      // Set the User Array list in ListView 
      final ListAdapter adapter = new SimpleAdapter(PlantillaChina.this, platoList, R.layout.itemlista, new String[] { 
          "platoId", "platoNombre", "platoDescripcion", "platoPrecio" }, new int[] {R.id.codigo, R.id.nombre, R.id.descripcion, R.id.precio }); 
      ListView myList = (ListView) findViewById(R.id.listaplatos); 
      myList.setAdapter(adapter); 
      myList.setOnItemClickListener(new OnItemClickListener() { 
       @Override 
       public void onItemClick(AdapterView<?> parent, View view, int 
             position, long id) 
       { 
        HashMap<String, String> obj = (HashMap<String, String>) adapter.getItem(position); 
        String platoId=(String) obj.get("platoId"); 
        String name = (String) obj.get("platoNombre"); 
        String description= (String) obj.get("platoDescripcion"); 
        final Dialog dialog = new Dialog(PlantillaChina.this); 
        dialog.setContentView(R.layout.platocompleto); 
        dialog.setTitle(name); 
        ImageView image=(ImageView) dialog.findViewById(R.id.imagen); 

//     image.setImageResource(R.drawable.ic_launcher); 
        String fname=new File(getFilesDir(),platoId +".jpg").getAbsolutePath(); 
        Bitmap Imagen=BitmapFactory.decodeFile(fname); 
        image.setImageBitmap(Imagen); 



        TextView texto=(TextView) dialog.findViewById(R.id.descripcionCompleta); 
        texto.setText(description); 
        dialog.getWindow().setBackgroundDrawable(new ColorDrawable(android.graphics.Color.BLACK)); 
        dialog.show(); 


       } 

      }); 
     } 
    }

新的错误日志

02-27 06:20:51.264: W/System.err(26443): java.io.FileNotFoundException: http://www.restaurantechinaimperial.com/menufotos/null.jpg 
02-27 06:20:51.265: W/System.err(26443): at com.android.okhttp.internal.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:186) 
02-27 06:20:51.266: W/System.err(26443): at com.example.proyectoprueba.prueba.productLookup(prueba.java:235) 
02-27 06:20:51.266: W/System.err(26443): at com.example.proyectoprueba.prueba.updateSQLite(prueba.java:186) 
02-27 06:20:51.267: W/System.err(26443): at com.example.proyectoprueba.prueba$1.onSuccess(prueba.java:122) 
02-27 06:20:51.267: W/System.err(26443): at com.loopj.android.http.AsyncHttpResponseHandler.onSuccess(AsyncHttpResponseHandler.java:232) 
02-27 06:20:51.268: W/System.err(26443): at com.loopj.android.http.AsyncHttpResponseHandler.onSuccess(AsyncHttpResponseHandler.java:220) 
02-27 06:20:51.269: W/System.err(26443): at com.loopj.android.http.AsyncHttpResponseHandler.onSuccess(AsyncHttpResponseHandler.java:245) 
02-27 06:20:51.270: W/System.err(26443): at com.loopj.android.http.AsyncHttpResponseHandler.handleMessage(AsyncHttpResponseHandler.java:365) 
02-27 06:20:51.270: W/System.err(26443): at com.loopj.android.http.AsyncHttpResponseHandler$ResponderHandler.handleMessage(AsyncHttpResponseHandler.java:135) 
02-27 06:20:51.271: W/System.err(26443): at android.os.Handler.dispatchMessage(Handler.java:110) 
02-27 06:20:51.272: W/System.err(26443): at android.os.Looper.loop(Looper.java:193) 
02-27 06:20:51.272: W/System.err(26443): at android.app.ActivityThread.main(ActivityThread.java:5323) 
02-27 06:20:51.273: W/System.err(26443): at java.lang.reflect.Method.invokeNative(Native Method) 
02-27 06:20:51.274: W/System.err(26443): at java.lang.reflect.Method.invoke(Method.java:515) 
02-27 06:20:51.274: W/System.err(26443): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:825) 
02-27 06:20:51.275: W/System.err(26443): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:641) 
02-27 06:20:51.275: W/System.err(26443): at dalvik.system.NativeStart.main(Native Method)

从法这里面调用检索部分updateSQLITE

HashMap<String, String> map = new HashMap<String, String>(); 
        // Add status for each plato in Hashmap 
        map.put("Id", obj.get("platoId").toString()); 
        map.put("status", "1"); 
    //I made the call here... it's right they why I did it? 
         platosynclist.add(map); 
         String productId=map.get("platoId"); 
         try { 
          productLookup(productId); 
         } catch (IOException e) { 
          e.printStackTrace(); 
         } 
        }

来源

2015-02-24 Avashiva

在给你一个可靠的解决方案之前，我想问你，为什么从url下载图片？有什么需要吗？或者只是在列表或网格视图中显示？ – IshRoid 2015-02-27 05:38:01

以及我想这将是可用这个应用程序的10个设备都是同步和他们将要使用它的地方没有最好的无线信号。是的，我正在列表或网格视图中显示它们。 – Avashiva 2015-02-27 05:54:59

那么为什么你不使用AsyncTask或LazyLoader？您的代码可能会挂起设备。 – IshRoid 2015-02-27 05:56:49

首先把你的大的网络交易操作AsynTask然后再更新您的productLookup方法如下

public String productLookup(String productID) throws IOException{ 

    URL url = new URL("http://www.samplewebsite.com/" + productID + ".jpg"); 

    InputStream input = null; 
    FileOutputStream output = null; 

    try { 
     String outputName = productID + "-thumbnail.jpg"; 

     input = url.openConnection().getInputStream(); 
     output = getApplicationContext().openFileOutput(outputName, Context.MODE_PRIVATE); 

     int read; 
     byte[] data = new byte[1024]; 
     while ((read = input.read(data)) != -1) 
      output.write(data, 0, read); 

     return outputName; 

    } finally { 
     if (output != null) 
      output.close(); 
     if (input != null) 
      input.close(); 
    } 
}

然后调用此方法

try { 
      productLookup(productId); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     }

最后读你保存的文件使用下面

private Bitmap decodeFile(File f){ 
     try { 
      //decode image size 
      BitmapFactory.Options o = new BitmapFactory.Options(); 
      o.inJustDecodeBounds = true; 
      BitmapFactory.decodeStream(new FileInputStream(f),null,o);  
      int scale=1; 
      //decode with inSampleSize 
      BitmapFactory.Options o2 = new BitmapFactory.Options(); 
      o2.inSampleSize=scale; 
      return BitmapFactory.decodeStream(new FileInputStream(f), null, o2); 
     } catch (FileNotFoundException e) {} 
     return null; 
    }

给出的代码，不要忘了加写外部存储许可。

添加以下代码的onCreate

StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build(); StrictMode.setThreadPolicy(policy);

要显示在对话框中的图像与enter code here

Bitmap Imagen=decodeFile(new File(getFilesDir(),platoId +".jpg")); 
      image.setImageBitmap(Imagen);

来源

2015-02-24 16:38:25 IshRoid

所以我打电话给decodeFile从其他活动。哪个（文件f）值应该是？ – Avashiva 2015-02-24 17:28:13

这个电话应该是这样吗？位图Imagen = decodeFile（new File（****））; ****应该在哪里存储路径？ – Avashiva 2015-02-24 17:36:32

是的，它是存储图像的路径 – IshRoid 2015-02-25 02:02:28

首先更换你的代码，你应该使用AsycnTask做任何HTTP调用不做它在应用主线程中，这里是官方链接：

http://developer.android.com/reference/android/os/AsyncTask.html

以及如何读取图像文件存储一次做到这一点：

File myImage = new File(filePath); 
try { 
      Bitmap pictureBitmap = MediaStore.Images.Media.getBitmap(activity.getContentResolver(), Uri.fromFile(myImage)); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 

     BitmapDrawable picture = new BitmapDrawable(activity.getResources(), pictureBitmap);

和外部存储权限添加到清单。

来源

2015-02-24 17:07:30 Rensodarwin

上下文中，存储内部存储器，并从中读取

回答

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