android下载图片显示在模拟器上

最新推荐文章于 2022-04-12 19:27:49 发布

原创最新推荐文章于 2022-04-12 19:27:49 发布 · 371 阅读

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本文介绍了一个简单的Android应用程序，该程序通过按钮点击触发图片的异步下载，并使用进度对话框显示下载进度。下载完成后，图片将显示在ImageView中。

1. main.xml文件内容为：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >


    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />


    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:text="@string/button" />


    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/textView1"
        android:layout_centerHorizontal="true"
        />


</RelativeLayout>

2. MainActivity

<pre name="code" class="java">import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;

import android.app.Activity;
import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

public class MainActivity extends Activity {

	private Button myButton = null;
	private ImageView imageView = null;
	private String image_path = "http://11.203.18.14:8080/image/001.png";
	
	private ProgressDialog dialog = null;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		myButton = (Button)findViewById(R.id.button1);
		imageView = (ImageView)findViewById(R.id.imageView1);
		dialog = new ProgressDialog(MainActivity.this);
		dialog.setTitle("提示信息");
		dialog.setMessage("正在下载,请稍后......");
		dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); //水平显示
		dialog.setCancelable(false);
		myButton.setOnClickListener(new View.OnClickListener() {
			
			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				new MyTask().execute(image_path);
			}
		});
	}

	public class MyTask extends AsyncTask<String, Integer, Bitmap>{

		
		@Override
		protected void onPreExecute() {
			// TODO Auto-generated method stub
			super.onPreExecute();
			dialog.show();
		}

		
		@Override
		protected void onProgressUpdate(Integer... values) {
			// TODO Auto-generated method stub
			super.onProgressUpdate(values);
			dialog.setProgress(values[0]);
		}


		@Override
		protected Bitmap doInBackground(String... params) {
			// TODO Auto-generated method stub
			//完成图片下载功能
			Bitmap bitmap = null;
			ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
			InputStream inputStream = null;
			try {
				HttpClient httpClient = new DefaultHttpClient();
				HttpGet httpGet = new HttpGet(params[0]);
				HttpResponse httpResponse = httpClient.execute(httpGet);
				if(httpResponse.getStatusLine().getStatusCode() == 200){
					inputStream = httpResponse.getEntity().getContent();
					long file_length = httpResponse.getEntity().getContentLength();
					int len = 0;
					byte[] data = new byte[1024];
					int total_length = 0;
					while((len=inputStream.read(data))!=-1){
						total_length+=len;
						int value = (int)((total_length/(float)file_length)*100);
						publishProgress(value);
						outputStream.write(data, 0, len);
						outputStream.flush();
					}
					
					byte[] result = outputStream.toByteArray();
					bitmap = BitmapFactory.decodeByteArray(result, 0, result.length);
				}                    
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}finally{
				if(inputStream!=null){
					try {
						inputStream.close();
					} catch (IOException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
				}
			}
			
			return bitmap;
		}


		@Override
		protected void onPostExecute(Bitmap result) {
			// TODO Auto-generated method stub
			super.onPostExecute(result);
			dialog.dismiss();
			imageView.setImageBitmap(result);
		}
		
		
	}
	@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;
	}

}

3. android注册文件一定要加访问网络的权限

<uses-permission android:name="android.permission.INTERNET"/>