android 下载网络图片 实例源码

【核心代码】

package com.example.downloadpic;

import java.io.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.os.StrictMode;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

public class MainActivity extends Activity {

	private final static String TAG = "AndroidTest2_3_3";
	private final static String ALBUM_PATH = Environment
			.getExternalStorageDirectory()   "/KXX/Pic/";
	private ImageView imageView;
	private Button btnSave;
	private Bitmap bitmap;
	private String fileName;

	@SuppressLint("NewApi")
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		btnSave = (Button) findViewById(R.id.btnSave);
		imageView = (ImageView) findViewById(R.id.iv);
		if (android.os.Build.VERSION.SDK_INT > 9) {
			StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder()
					.permitAll().build();
			StrictMode.setThreadPolicy(policy);
		}
		String filePath = "http://e.hiphotos.baidu.com/image/pic/item/f3d3572c11dfa9ecc675b97f61d0f703918fc17b.jpg";
		fileName = "est.jpg";
		try {
			// ////////////// 取得的是byte数组, 从byte数组生成bitmap
			byte[] data = getImage(filePath);
			if (data != null) {
				bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);// bitmap
			}
			bitmap = BitmapFactory.decodeStream(getImageStream(filePath));
			if (bitmap != null) {
				
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		// 下载图片
		btnSave.setOnClickListener(new Button.OnClickListener() {
			public void onClick(View v) {
				new Thread(saveFileRunnable).start();
				Bitmap bitmap = BitmapFactory.decodeFile(ALBUM_PATH   fileName);
				Drawable drawable = new BitmapDrawable(bitmap);
				imageView.setBackgroundDrawable(drawable);
				imageView.invalidate();  
			}
		});
	}
	
	
	public boolean fileIsExists() {
		try {
			String ALBUM_PATH = Environment.getExternalStorageDirectory()
					  "/KXX/";
			String fileName = "first_bg.jpg";
			File f = new File(ALBUM_PATH fileName);
			if (!f.exists()) {
				return false;
			}

		} catch (Exception e) {
			// TODO: handle exception
			return false;
		}
		return true;
	}
	
	/**
	 * Get image from newwork
	 * 
	 * @param path
	 *            The path of image
	 * @return byte[]
	 * @throws Exception
	 */
	public byte[] getImage(String path) throws Exception {
		URL url = new URL(path);
		HttpURLConnection conn = (HttpURLConnection) url.openConnection();
		conn.setConnectTimeout(5 * 1000);
		conn.setRequestMethod("GET");
		InputStream inStream = conn.getInputStream();
		if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) {
			return readStream(inStream);
		}
		return null;
	}

	/**
	 * Get image from newwork
	 * 
	 * @param path
	 *            The path of image
	 * @return InputStream
	 * @throws Exception
	 */
	public InputStream getImageStream(String path) throws Exception {
		URL url = new URL(path);
		HttpURLConnection conn = (HttpURLConnection) url.openConnection();
		conn.setConnectTimeout(5 * 1000);
		conn.setRequestMethod("GET");
		if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) {
			return conn.getInputStream();
		}
		return null;
	}

	/**
	 * Get data from stream
	 * 
	 * @param inStream
	 * @return byte[]
	 * @throws Exception
	 */
	public static byte[] readStream(InputStream inStream) throws Exception {
		ByteArrayOutputStream outStream = new ByteArrayOutputStream();
		byte[] buffer = new byte[1024];
		int len = 0;
		while ((len = inStream.read(buffer)) != -1) {
			outStream.write(buffer, 0, len);
		}
		outStream.close();
		inStream.close();
		return outStream.toByteArray();
	}

	/**
	 * 保存文件
	 * 
	 * @param bm
	 * @param fileName
	 * @throws IOException
	 */
	public void saveFile(Bitmap bm, String fileName) throws IOException {
		File dirFile = new File(ALBUM_PATH);
		if (!dirFile.exists()) {
			dirFile.mkdir();
		}
		File myCaptureFile = new File(ALBUM_PATH   fileName);
		BufferedOutputStream bos = new BufferedOutputStream(
				new FileOutputStream(myCaptureFile));
		bm.compress(Bitmap.CompressFormat.JPEG, 80, bos);
		bos.flush();
		bos.close();
	}

	private Runnable saveFileRunnable = new Runnable() {
		@Override
		public void run() {
			try {
				saveFile(bitmap, fileName);
			} catch (IOException e) {
				e.printStackTrace();
			}
		}

	};

}