图片下载

package com.example.tupian;

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.MalformedURLException;
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 MainActivity<IcsTestActivity> extends Activity {


    private final static String TAG = "MainActivity";
    private final static String ALBUM_PATH
            = Environment.getExternalStorageDirectory()+"/TT/";
    private ImageView mImageView;
    private ImageView mImageView1;
    private Button mBtnSave;
    private ProgressDialog mSaveDialog = null;
    private Bitmap mBitmap;
    private String mFileName;
    private String mSaveMessage;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        mImageView = (ImageView)findViewById(R.id.IV);
        mImageView1 = (ImageView)findViewById(R.id.IV1);
        mBtnSave = (Button)findViewById(R.id.BT);

        new Thread(connectNet).start();


//下载图片
mBtnSave.setOnClickListener(new Button.OnClickListener(){
    public void onClick(View v) {
        mSaveDialog = ProgressDialog.show(MainActivity.this, "保存图片", "图片正在保存中，请稍等...", true);
        new Thread(saveFileRunnable).start();
        showiv();
}

    
});

    }
    private void showiv() {
        // TODO Auto-generated method stub
        BitmapFactory factory= new BitmapFactory();
        Bitmap bm= factory.decodeFile(ALBUM_PATH+"test.jpg");
        mImageView1.setImageBitmap(bm);
    }
    
    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;
    }

   
    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;
    }
   
    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();
    }

   
    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(mBitmap, mFileName);
                mSaveMessage = "图片保存成功！";
            } catch (IOException 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(MainActivity.this, mSaveMessage, Toast.LENGTH_SHORT).show();
        }
    };


    private Bitmap getImageBitmap(String url){
        URL imgUrl = null;
        Bitmap bitmap = null;
        try {
            imgUrl = new URL(url);
            HttpURLConnection conn = (HttpURLConnection)imgUrl.openConnection();
            conn.setDoInput(true);
            conn.connect();
            InputStream is = conn.getInputStream();
            bitmap = BitmapFactory.decodeStream(is);
            is.close();
        } catch (MalformedURLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }catch(IOException e){
            e.printStackTrace();
        }
        return bitmap;
    }
   
    private Runnable connectNet = new Runnable(){
        @Override
        public void run() {
            try {
                String filePath = "https://ss0.baidu.com/73t1bjeh1BF3odCf/it/u=1014815171,2992716709&fm=96&s=8010CD3314A5D7153FACE9CD0300A0A3";
                mFileName = "test.jpg";

                //以下是取得图片的两种方法
                //////////////// 方法1：取得的是byte数组, 从byte数组生成bitmap
              /*  byte[] data = getImage(filePath);
                if(data!=null){
                    mBitmap = BitmapFactory.decodeByteArray(data, 0, data.length);// bitmap
                }else{
                    Toast.makeText(IcsTestActivity.this, "Image error!", 1).show();
                }
                ////////////////////////////////////////////////////////
*/
                //******** 方法2：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(MainActivity.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
            }
        }
    };
   
}

<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"
 >

    <ImageView
        android:layout_width="200dp"
        android:layout_height="200dp"
        android:id="@+id/IV" />
<Button  android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/BT"
        android:layout_below="@id/IV"/>
<ImageView
    android:layout_below="@id/BT"
      android:layout_width="200dp"
        android:layout_height="600dp"
        android:id="@+id/IV1" />
</RelativeLayout>

权限

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