android下载图片在手机中展示

在项目开发中从互联网上下载图片是经常用到的功能，再次总结一下

1.普通的下载方式

布局文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent">
  
    <ImageView android:src="@drawable/icon" 
	    android:layout_width="wrap_content" 
	    android:id="@+id/imgPic" 
	    android:layout_gravity="center|center_vertical" 
	    android:layout_height="fill_parent">
    </ImageView>
        
</LinearLayout>

java文件

public class DownloadImage extends Activity {
	private ImageView imgPic;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.download_image);
		imgPic = (ImageView) findViewById(R.id.imgPic);
		String url = "http://ww1.sinaimg.cn/bmiddle/6834c769jw1djjf4p3p9rj.jpg";
		loadRmoteImage(url);
	}

	/**
	 * @param imgUrl
	 *            远程图片文件的URL
	 *             
	 *            下载远程图片
	 */
	private void loadRmoteImage(String imgUrl) {
		URL fileURL = null;
		Bitmap bitmap = null;
		try {
			fileURL = new URL(imgUrl);
		} catch (MalformedURLException err) {
			err.printStackTrace();
		}
		try {
			HttpURLConnection conn = (HttpURLConnection) fileURL
					.openConnection();
			conn.setDoInput(true);
			conn.connect();
			InputStream is = conn.getInputStream();
			int length = (int) conn.getContentLength();
			if (length != -1) {
				byte[] imgData = new byte[length];
				byte[] buffer = new byte[512];
				int readLen = 0;
				int destPos = 0;
				while ((readLen = is.read(buffer)) > 0) {
					System.arraycopy(buffer, 0, imgData, destPos, readLen);
					destPos += readLen;
				}
				bitmap = BitmapFactory.decodeByteArray(imgData, 0,
						imgData.length);
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
		imgPic.setImageBitmap(bitmap);
	}

2.带进度条的下载

有时候网络差，或者是图片太大，会出现黑屏的情况，用户体验比较差，那么增加一个进度条是提高用户体验的好方法

/**
 * @author xushilin xsl xushilin@kingtoneinfo.com
 * @version： 创建时间：2011-7-27 下午02:55:56 
 * 说 明: android中下载图片 
 * 修改历史：
 */
public class DownloadImage extends Activity {
	private ImageView imgPic;	
	private ProgressBar progressBar;
	private int totalSize=0;
	private int size=0;
	private Handler mHandler;
	String url = "http://ww1.sinaimg.cn/bmiddle/6834c769jw1djjf4p3p9rj.jpg";
	private Bitmap bitmap=null;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.download_image);
		imgPic = (ImageView) findViewById(R.id.imgPic);
		
		progressBar = (ProgressBar) findViewById(R.id.progressBar);
		progressBar.setProgress(getProgressInt(progressBar.getMax()));
		mHandler = new Handler() {
			public void handleMessage(Message msg) {				
				progressBar.setProgress(getProgressInt(progressBar.getMax()));		
				if(bitmap!=null){
					imgPic.setImageBitmap(bitmap);
				}
			}
		};
		new Thread(){	
			public void run(){
				loadRmoteImage(url);
			}
		}.start();
	}

	/**
	 * @param imgUrl
	 *            远程图片文件的URL
	 *             
	 *            下载远程图片
	 */
	private void loadRmoteImage(String imgUrl) {
		URL fileURL = null;		
		try {
			fileURL = new URL(imgUrl);
		} catch (MalformedURLException err) {
			err.printStackTrace();
		}
		try {
			HttpURLConnection conn = (HttpURLConnection) fileURL
					.openConnection();
			conn.setDoInput(true);
			conn.connect();
			InputStream is = conn.getInputStream();
			int length = (int) conn.getContentLength();
			totalSize=length;
			if (length != -1) {
				byte[] imgData = new byte[length];
				byte[] buffer = new byte[512];
				int readLen = 0;
				int destPos = 0;
				while ((readLen = is.read(buffer)) > 0) {					
					System.arraycopy(buffer, 0, imgData, destPos, readLen);
					destPos += readLen;
					size=destPos;
					mHandler.sendEmptyMessage(1);
					Thread.sleep(100);
				}
				bitmap = BitmapFactory.decodeByteArray(imgData, 0,
						imgData.length);
				mHandler.sendEmptyMessage(1);
			}
		} catch (IOException e) {
			e.printStackTrace();
		} catch (InterruptedException e) {			
			e.printStackTrace();
		}
		
	}
	private  int getProgressInt(int max) {
		int result = (totalSize > 0) ? (int) (size * max * 1.0 / totalSize) : 0;
		return result;
	}	
}

效果如下：

下载过程

下载完成：