android - 如何从 Web 服务获取图像到 android 应用程序？

Question

我正在尝试根据它们的 ID 号从服务器加载图像。哪个是从网络服务中检索它的最佳方法？

package com.crispsys;

import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;

import android.app.Activity;
import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

public class imageviewer extends Activity {
    /** Called when the activity is first created. */
    
    Bitmap image; 
    private TextView ordernumber;
     ImageView imageView;
     private Button butt;
     String Str="image",ordno;
     
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.imageviewerr);
        
         this.butt = (Button) this.findViewById(R.id.getbutt);
          this.imageView =(ImageView) findViewById(R.id.blodig);
          this.ordernumber=(TextView)this.findViewById(R.id.ordernotext);
          
          final Bundle getdata = getIntent().getExtras();
          
          if (getdata != null)    
          {
              ordno=getdata.getString("orono");
              ordernumber.setText(ordno);
          }
         
        
        this.butt.setOnClickListener(new View.OnClickListener() {
            
            public void onClick(View v) {
                // TODO Auto-generated method stub
                
                
                Toast.makeText(getApplicationContext(),"loading" , Toast.LENGTH_LONG).show();
                
                      URL url = null;
                
                
                      try 
                      {
                        
                          url = new URL("http://www.cyberstudents.in/aaa/car.jpg");
                          
                      }
                      catch (MalformedURLException e) 
                      {
                          e.printStackTrace();
                      }
                      try {
                          image = BitmapFactory.decodeStream(url.openStream());
                         
                      } 
                      catch (IOException e) 
                      {
                          e.printStackTrace();
                      }
                
                imageView.setImageBitmap(image);
            }
        });
       
    }
}

XML 文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:background="@drawable/cr_isp"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TableRow
        android:id="@+id/tableRow1"
        android:layout_width="match_parent"
        android:gravity="center"
        android:paddingTop="20dp"
        android:layout_height="wrap_content" >

        <TextView
            android:id="@+id/ordernotext"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="#8B8682"
            android:text="" />

       
    </TableRow> 
    
    <TableRow
        android:id="@+id/tableRow1"
        android:layout_width="match_parent"
        android:gravity="center"
        android:paddingTop="20dp"
        android:layout_height="wrap_content" >

        <Button
            android:id="@+id/getbutt"
            android:layout_width="210dp"
            android:layout_height="40dp"
            android:background="@drawable/bcbut"
            android:textColor="#8B8682"
            android:text="Get Block Dig" />
        
    </TableRow>

    <TableRow
        android:id="@+id/tableRow2"
        android:layout_width="match_parent"
        android:gravity="center"
        android:paddingTop="20dp"
        android:layout_height="wrap_content" >

        <ImageView
            android:id="@+id/blodig"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/ic_launcher" />

    </TableRow>

</LinearLayout>

尝试使用此代码，但我只能使用小尺寸图像。当我去一个大尺寸的图像时，它不起作用。它保持不变，我找不到任何错误。它显示相同的屏幕。

score 11 · Accepted Answer

您可以使用异步图像加载器异步加载图像。检查下面的代码。

private class FetchImageTask extends AsyncTask<String, Integer, Bitmap> {
    @Override
    protected Bitmap doInBackground(String... arg0) {
        Bitmap b = null;
        try {
            b = BitmapFactory.decodeStream((InputStream) new URL(arg0[0]).getContent());
        }
        catch (MalformedURLException e) {
            e.printStackTrace();
        }
        catch (IOException e) {
            e.printStackTrace();
        }
        return b;
    }
}

要实现使用此代码。

new FetchImageTask() {
        @Override
        protected void onPostExecute(Bitmap result) {
            if (result != null) {
                image.setImageBitmap(result);
            }
        }
    }.execute("IMAGE_URL");

score 2 · Accepted Answer

这取决于服务器的响应，即它以何种形式提供图像。它可以是base 64 字符串或 URL的形式。

如果它是一个 base 64 字符串，那么您可以使用 java 中的 base64 类对其进行编码，如果它是 url，那么您只需通过将图像从 url 转换为位图来使用位图设置图像。您需要通过以下方式使用 httpGet 向服务器发出 get 请求。

public static String connect(String url) throws IOException {
    HttpClient httpclient = new DefaultHttpClient();
    HttpGet httpget = new HttpGet(url);
    HttpResponse response;
    try {
        response = httpclient.execute(httpget);
        HttpEntity entity = response.getEntity();
        if (entity != null) {
            InputStream instream = entity.getContent();
            result = convertStreamToString(instream);
            instream.close();
        }
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return result;
}


private static String convertStreamToString(InputStream input) {
    /*
     * To convert the InputStream to String we use the
     * BufferedReader.readLine() method. We iterate until the BufferedReader
     * return null which means there's no more data to read. Each line will
     * appended to a StringBuilder and returned as String.
     */
    BufferedReader reader = new BufferedReader(new InputStreamReader(input));
    StringBuilder buffer = new StringBuilder();
    String line = null;
    try {
        while ((line = reader.readLine()) != null) {
            buffer.append(line + "\n");
        }
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
            input.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return buffer.toString();
}

score 1 · Accepted Answer

1

使用该 ID 号向 Web 服务发出 Get 请求，该服务将使用所需的图像进行响应。

于 2012-05-15T05:21:08.943 回答

android - 如何从 Web 服务获取图像到 android 应用程序？

3 回答 3

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