android 下载图片保存在sdcard并显示可拖动缩放

java代码

package com.example.catchlong;
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.annotation.TargetApi;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PointF;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.FloatMath;
import android.util.Log;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.view.GestureDetector.OnGestureListener;
import android.view.View.OnTouchListener;
import android.view.animation.AnimationUtils;
import android.widget.ImageView;
import android.widget.Toast;

@SuppressLint({ "NewApi", "NewApi", "NewApi", "NewApi" })
@TargetApi(5)
public class ImageActivity extends Activity implements OnTouchListener {
    //implements OnTouchListener {
    private ImageView imgview;
    private ImageView img;
 
    
    private Matrix matrix=new Matrix();
    private Matrix savedMatrix=new Matrix();
    
    static final int NONE = 0;  
    static final int DRAG = 1;  
    static final int ZOOM = 2;  
    int mode = NONE;  

    // Remember some things for zooming  
    PointF start = new PointF();  
    PointF mid = new PointF();  
    float oldDist = 1f;  
    
    //private GestureDetector gesture;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        this.setContentView(R.layout.imagectrl);
        imgview=(ImageView)this.findViewById(R.id.imag);
        downloadImage();
        //imgview.setAnimation(AnimationUtils.loadAnimation(this, R.anim.newanim));
        
        
        img=(ImageView)this.findViewById(R.id.imag);
        Matrix mt=img.getImageMatrix();    
        //mt.postRotate(30);
        mt.postScale(0.5f,0.5f);mt.postScale(1.5f,1.5f);
        //mt.postRotate(30, 130, 100);
        mt.postTranslate(100, 10);
        
        img.setImageMatrix(mt);
        
    
        //imgview.setLongClickable(true);
        
        //imgview.setImageBitmap(BitmapFactory.decodeResource(this.getResources(), R.drawable.xieer_1));
        imgview.setOnTouchListener(this);
        imgview.setLongClickable(true);
        
    }
    private float spacing(MotionEvent event) {  
        float x = event.getX(0) - event.getX(1);  
        float y = event.getY(0) - event.getY(1);  
        return FloatMath.sqrt(x * x + y * y);  
}  

 
      private void midPoint(PointF point, MotionEvent event) {  
        float x = event.getX(0) + event.getX(1);  
        float y = event.getY(0) + event.getY(1);  
        point.set(x / 2, y / 2);  
}  

    @TargetApi(8)
    public boolean onTouch(View v, MotionEvent event) {
        // TODO Auto-generated method stub
        /*
        Log.d("Infor", "类别:"+event.getAction());
        Log.d("Infor", "mask:"+event.getActionMasked());
        Log.d("Infor", "index:"+event.getActionIndex());
        Log.d("Infor", "points:"+event.getPointerCount());*/
        Log.d("Infor", "size:"+event.getSize());
        if(event.getActionMasked()==MotionEvent.ACTION_POINTER_UP)
            Log.d("Infor", "多点操作");
        switch(event.getActionMasked()){
        case MotionEvent.ACTION_DOWN:
              matrix.set(imgview.getImageMatrix());
              savedMatrix.set(matrix);
              start.set(event.getX(),event.getY());
              Log.d("Infor", "触摸了...");
              mode=DRAG;
              break;
        case MotionEvent.ACTION_POINTER_DOWN:  //多点触控
             oldDist=this.spacing(event);
            if(oldDist>10f){
             Log.d("Infor", "oldDist"+oldDist);
             savedMatrix.set(matrix);
             midPoint(mid,event);
             mode=ZOOM;
            }
            break;
        case MotionEvent.ACTION_POINTER_UP:
            mode=NONE;
            break;
        case MotionEvent.ACTION_MOVE:
            if(mode==DRAG){         //此实现图片的拖动功能...
                matrix.set(savedMatrix);
                matrix.postTranslate(event.getX()-start.x, event.getY()-start.y);
            }
                else if(mode==ZOOM){// 此实现图片的缩放功能...
             float newDist=spacing(event);
             if(newDist>10){
                 matrix.set(savedMatrix);
                 float scale=newDist/oldDist;
                 matrix.postScale(scale, scale, mid.x, mid.y);                 
             }
                }
            break;
        }
        imgview.setImageMatrix(matrix);
        return false;
    }    
    private void downloadImage(){

           String filePath= "http://img.jdxi.net/upload/2012/9/201209011610355146.jpg";

           @SuppressWarnings("unused")
        String imgName ="liying.jpg";

             //使用【方法1】取得的是InputStream，直接从InputStream生成bitmap

            try{

                Bitmap bitmap = BitmapFactory.decodeStream(getImageStream(filePath));

                if(bitmap!=null){

                    saveFile(bitmap, "liying.jpg");  //调用保存方法
                  
                    String str2 = "/sdcard/mbookyang/liying.jpg";

                    File file = new File(str2);

                    if(file.exists()){     //判断文件是否存在

                        Bitmap bm = BitmapFactory.decodeFile(str2);
                        //由File获取图片并转为Bitmap

                       imgview.setImageBitmap(bm);

                    }

                }

            }

            catch(Exception e) {            
                Toast.makeText(ImageActivity.this,"下载图片失败", Toast.LENGTH_SHORT).show();  

                e.printStackTrace();

            }

           

        }

       

        //方法1

        public InputStream getImageStream(String path)throws Exception{     

            URL url = new URL(path);     

            HttpURLConnection conn =(HttpURLConnection) url.openConnection();     

            conn.setConnectTimeout(5 * 1000);        //设定超时

            conn.setRequestMethod("GET");   //GET为下载，POST为上传

            if(conn.getResponseCode()== HttpURLConnection.HTTP_OK){     

                return conn.getInputStream();         //获得数据流  

            }     

            return null;   

        } 

       

        //方法2

        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 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Bitmap为图片文件

        public void saveFile(Bitmap bitmap, String fileName) throws IOException {  

            File dirFile = new File("/sdcard/mbookyang");  

            if(!dirFile.exists()){  //判断路径是否存在，不存在则创建

                dirFile.mkdir();  

            }

            File savePath = new File("/sdcard/mbookyang/" + fileName);  //保存路径

            BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(savePath));  

            bitmap.compress(Bitmap.CompressFormat.JPEG, 80, bos);  //质量压缩为80%

            bos.flush();  

            bos.close();  

        }

}