Android中使用HttpURLConnection实现GET POST JSON数据与下载图片

三、下载图片显示下载进度

package com.example.demo; 
 
import java.io.ByteArrayInputStream; 
import java.io.ByteArrayOutputStream; 
import java.io.IOException; 
import java.io.InputStream; 
import java.net.HttpURLConnection; 
import java.net.URL; 
 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.os.AsyncTask; 
import android.os.Handler; 
import android.os.Message; 
import android.util.Log; 
 
public class ImageLoadTask extends AsyncTask<String, Void, Bitmap> { 
 private Handler handler; 
 
 public ImageLoadTask(Handler handler) { 
  this.handler = handler; 
 } 
 
 protected void onPostExecute(Bitmap result) { 
  Message msg = new Message(); 
  msg.obj = result; 
  handler.sendMessage(msg); 
 } 
 
 protected Bitmap doInBackground(String... getUrls) { 
  InputStream inputStream = null; 
  HttpURLConnection urlConnection = null; 
 
  try { 
   // open connection 
   URL url = new URL(getUrls[0]); 
   urlConnection = (HttpURLConnection) url.openConnection(); 
   /* for Get request */ 
   urlConnection.setRequestMethod("GET"); 
   int fileLength = urlConnection.getContentLength(); 
   int statusCode = urlConnection.getResponseCode(); 
   if (statusCode == 200) { 
    inputStream = urlConnection.getInputStream(); 
    byte data[] = new byte[4096]; 
    long total = 0; 
    int count; 
    ByteArrayOutputStream output = new ByteArrayOutputStream(); 
    while ((count = inputStream.read(data)) != -1) { 
     total += count; 
     // publishing the progress.... 
     if (fileLength > 0 && handler != null) { 
      handler.sendEmptyMessage(((int) (total * 100 / fileLength)) - 1); 
     } 
     output.write(data, 0, count); 
    } 
    ByteArrayInputStream bufferInput = new ByteArrayInputStream(output.toByteArray()); 
    Bitmap bitmap = BitmapFactory.decodeStream(bufferInput); 
    inputStream.close(); 
    bufferInput.close(); 
    output.close(); 
    Log.i("image", "already get the image by uuid : " + getUrls[0]); 
    handler.sendEmptyMessage(100); 
    return bitmap; 
   } 
  } catch (Exception e) { 
   e.printStackTrace(); 
  } finally { 
   if (inputStream != null) { 
    try { 
     inputStream.close(); 
    } catch (IOException e) { 
     e.printStackTrace(); 
    } 
   } 
   if (urlConnection != null) { 
    urlConnection.disconnect(); 
   } 
  } 
  return null; 
 } 
 
} 

总结：使用HttpURLConnection提交JSON数据的时候编码方式为UTF-8所有中文字符请一定要预先转码为UTF-8，然后在后台服务器对应的API中解码为UTF-8，不然就会报错HTTP 400。

以上就是本文的全部内容，希望对大家的学习Android软件编程有所帮助。