android网络编程--从网络下载图片，并保存到内存卡

功能1：从网络上取得的图片显示到imageview上面，生成Bitmap时有两种方法，一种是先转换为byte[]，再生成bitmap；一种是直接用InputStream生成bitmap。功能2：点击按钮将显示的图片下载到sd卡上。原文地址：http://www.cnblogs.com/gzggyy/archive/2013/05/18/3085552.html

下面就贴一种直接用InputStream生成bitmap的代码吧，另外一种直接看原文咯。mark一下，方便自己用

package com.robin.httpcommunicationtest;

import java.io.BufferedOutputStream;
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.app.Activity;
import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

public class SaveImageActivity extends Activity {

    private static final String TAG = "SaveImageActivity";
    private final static String ALBUM_PATH = Environment
            .getExternalStorageDirectory() + "/download_test/";
    private ImageView mImageView;
    private Button mBtnSave;
    private ProgressDialog mSaveDialog = null;
    private Bitmap mBitmap;
    private String mFileName;
    private String mSaveMessage;
    private Thread connectThread;
    private Thread saveThread;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.image_download);

        mImageView = (ImageView) findViewById(R.id.imgSource);
        mBtnSave = (Button) findViewById(R.id.btnSave);

        connectThread = new Thread(connectNet);
        connectThread.start();

        mBtnSave.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                mSaveDialog = ProgressDialog.show(SaveImageActivity.this,
                        "保存图片", "图片正在保存，请稍后...", true);
                saveThread = new Thread(saveFileRunnable);
                saveThread.start();
            }
        });
    }

    private Runnable connectNet = new Runnable() {

        @Override
        public void run() {
            try {
                String filePath = "http://img.my.csdn.net/uploads/201402/24/1393242467_3999.jpg";
                mFileName = "robin.jpg";
                // 取得的是inputstream，直接从inputstream生成bitmap
                mBitmap = BitmapFactory.decodeStream(getImageStream(filePath));
                // 发送消息，通知handler在主线程中更新ui
                connectHanlder.sendEmptyMessage(0);
                Log.d(TAG, "set image ...");
            } catch (Exception e) {
                Toast.makeText(SaveImageActivity.this, "无法链接网络！", 1).show();
                e.printStackTrace();
            }

        }
    };
    private Handler connectHanlder = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            Log.d(TAG, "display image");
            // 更新UI，显示图片
            if (mBitmap != null) {
                mImageView.setImageBitmap(mBitmap);// display image
            }
        }
    };
    private Runnable saveFileRunnable = new Runnable() {

        @Override
        public void run() {
            try {
                saveFile(mBitmap, mFileName);
                mSaveMessage = "图片保存成功！";
            } catch (Exception e) {
                mSaveMessage = "图片保存失败！";
                e.printStackTrace();
            }
            messageHandler.sendMessage(messageHandler.obtainMessage());
        }
    };

    private Handler messageHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            mSaveDialog.dismiss();
            Log.d(TAG, mSaveMessage);
            Toast.makeText(SaveImageActivity.this, mSaveMessage,
                    Toast.LENGTH_SHORT).show();
        }
    };

    /*
     * 从网络获取图片
     */
    protected InputStream getImageStream(String path) throws Exception {
        URL url = new URL(path);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setConnectTimeout(10 * 1000);
        conn.setRequestMethod("GET");
        if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) {
            return conn.getInputStream();
        }
        return null;
    }

    /*
     * 保存文件
     */
    protected 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();
    }
}

demo下载地址：

http://download.csdn.net/detail/lanhuzi9999/7507995