android开发获取网络图片并可拖拽移动

来源：互联网发布：有感情朗读软件编辑：程序博客网时间：2024/06/05 23:52

这一篇讲获取网络图片，然后显示出来，并对其操作，如拖拽，放大，缩小，移动。

首先，先访问网络图片，代码如下：

先定义一个线程，因为在android4.0以上的系统中，不支持有阻塞的操作在主线程里发生，所以得新定义一个线程，这个线程包括访问网络操作。

Thread xiaoli_thread=new Thread(new Runnable(){@Override//该线程通过网络，获取校历的数据流public void run() { try{ URL url= new URL(PATH); HttpURLConnection conn= (HttpURLConnection)url.openConnection(); conn.setConnectTimeout(6 * 1000); // 别超过6秒 conn.setDoInput(true); conn.connect(); InputStream inputStream=conn.getInputStream(); if(inputStream==null){ Log.i(TAG,"picture got failed"); }else{ bmp= BitmapFactory.decodeStream(inputStream); Log.i(TAG,"picture got");  MAX_W=bmp.getWidth()*2; MAX_H=bmp.getHeight()*2; MIN_W=bmp.getWidth()/2; MIN_H=bmp.getHeight()/2;  Message msg=new Message(); msg.what=SHOW_PICTURE; handler.sendMessage(msg); } }catch (SocketTimeoutException e){ Log.i(TAG,"SocketTimeoutException"); e.printStackTrace(); } catch (MalformedURLException e){ Log.i(TAG,"MalformedURLException"); e.printStackTrace(); }catch (IOException e) { Log.i(TAG,"IOException"); e.printStackTrace(); } } });

再定义一个handler获取线程发送的消息

final Handler handler=new Handler(){    @Override//接收线程发出的信息，缓冲框消失public void handleMessage(Message msg){switch(msg.what){case SHOW_PICTURE: img.setImageBitmap(bmp); dialog.dismiss();break;}}};

然后，在oncreate()方法中

//后台启动校历线程,加载学校校历图片xiaoli_thread.start();Log.i(TAG,"new xiaoli_thread start!");

这样网络上的图片就可以显示出来了，当然还要有配置文件，这里就不说了。

接下来，就是对图片的操作。

先定义触摸、放大、缩小事件

img.setOnTouchListener(new MulitPointTouchListener(img));

zoomcon=(ZoomControls)super.findViewById(R.id.zoomcontrol);this.zoomcon.setOnZoomInClickListener(new onzoominclicklistener());//放大监听this.zoomcon.setOnZoomOutClickListener(new onzoomoutclicklistener());//缩小监听zoomcon.setIsZoomInEnabled(true);    zoomcon.setIsZoomOutEnabled(true);

然后，再写具体的方法

1、触摸即多点触控方法

/** * @继承OnTouchListener实现多点触控 */public class MulitPointTouchListener implements OnTouchListener {        Matrix matrix = new Matrix();        Matrix savedMatrix = new Matrix();         public ImageView image;        static final int NONE = 0;        static final int DRAG = 1; //拖拽       static final int ZOOM = 2; //缩放       int mode = NONE;          PointF start = new PointF();        PointF mid = new PointF();        float oldDist = 1f;        public MulitPointTouchListener(ImageView image) {            super();            this.image = image;        }          @Override        public boolean onTouch(View v, MotionEvent event) {            this.image.setScaleType(ScaleType.MATRIX);            ImageView view = (ImageView) v;          switch (event.getAction() & MotionEvent.ACTION_MASK) {          case MotionEvent.ACTION_DOWN:            Log.w("FLAG", "ACTION_DOWN");                         //设置底部组件的可见性            if(IsVisible){              bottom.setVisibility(View.INVISIBLE);              IsVisible = false;              Log.i(TAG,"onClick1");        }else{              bottom.setVisibility(View.VISIBLE);              IsVisible = true;              Log.i(TAG,"onClick2");        }              matrix.set(view.getImageMatrix());                savedMatrix.set(matrix);                start.set(event.getX(), event.getY());                mode = DRAG;                break;            case MotionEvent.ACTION_POINTER_DOWN:                Log.w("FLAG", "ACTION_POINTER_DOWN");              oldDist = spacing(event);                if (oldDist > 10f) {                    savedMatrix.set(matrix);                    midPoint(mid, event);                    mode = ZOOM;                }                break;            case MotionEvent.ACTION_UP:                Log.w("FLAG", "ACTION_UP");          case MotionEvent.ACTION_POINTER_UP:                Log.w("FLAG", "ACTION_POINTER_UP");              mode = NONE;                break;            case MotionEvent.ACTION_MOVE:                Log.w("FLAG", "ACTION_MOVE");              if (mode == DRAG) {                    matrix.set(savedMatrix);                    matrix.postTranslate(event.getX() - start.x, event.getY()- start.y);                } else if (mode == ZOOM) {                    float newDist = spacing(event);                    if (newDist > 10f) {                        matrix.set(savedMatrix);                        float scale = newDist / oldDist;                        matrix.postScale(scale, scale, mid.x, mid.y);                    }                }                break;            }         view.setImageMatrix(matrix);            return 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);        }     ｝

2、放大操作

/** * @放大图片 */private class onzoominclicklistener implements OnClickListener{@Overridepublic void onClick(View v) {int bmpWidth = bmp.getWidth();     int bmpHeight = bmp.getHeight();     //设置图片放大但比例     double scale = 1.25;     //计算这次要放大的比例     scaleWidth = (float)(scaleWidth*scale);     scaleHeight = (float)(scaleHeight*scale);     //产生新的大小但Bitmap对象     Matrix matrix = new Matrix();     matrix.postScale(scaleWidth, scaleHeight);     try{     Bitmap resizeBmp = Bitmap.createBitmap(bmp,0,0,bmpWidth,bmpHeight,matrix,true);     if(resizeBmp.getWidth()>=(MAX_W-350 )|| resizeBmp.getHeight()>=(MAX_H-350)){     zoomcon.setIsZoomInEnabled(false);     }else{     img.setImageBitmap(resizeBmp);     zoomcon.setIsZoomOutEnabled(true);     }     }catch(IllegalArgumentException e){        Log.e(TAG,"IllegalArgumentException");        e.printStackTrace();     }catch(Exception e){        Log.e(TAG,"Exception");        e.printStackTrace();     }}}

3、缩小操作

/** * @缩小图片 */private class onzoomoutclicklistener implements OnClickListener{@Overridepublic void onClick(View v) {int bmpWidth=bmp.getWidth();            int bmpHeight=bmp.getHeight();                   /* 设置图片缩小的比例 */          double scale=0.8;           /* 计算出这次要缩小的比例 */            scaleWidth=(float) (scaleWidth*scale);            scaleHeight=(float) (scaleHeight*scale);            /* 产生reSize后的Bitmap对象 */          Matrix matrix = new Matrix();           matrix.postScale(scaleWidth, scaleHeight);          try{        Bitmap resizeBmp = Bitmap.createBitmap(bmp,0,0,bmpWidth, bmpHeight,matrix,true);         if(resizeBmp.getWidth()<=MIN_W || resizeBmp.getHeight()<=MIN_H){     zoomcon.setIsZoomOutEnabled(false);     }else{     img.setImageBitmap(resizeBmp);     zoomcon.setIsZoomInEnabled(true);     }         }catch(IllegalArgumentException e){        Log.e(TAG,"IllegalArgumentException");        e.printStackTrace();        }catch(Exception e){        Log.e(TAG,"Exception");        e.printStackTrace();        }        }}

啊，代码有点长，最好在最后还要加上回收图片，因为它占的内存比较多

 @Override    protected void onStop() {      if(bmp!=null){   if(!bmp.isRecycled()){   bmp.recycle();   //回收图片所占的内存   bmp=null;           System.gc();  //提醒系统及时回收   }      }      super.onStop();   }      @Override   protected void onDestroy() {   super.onDestroy();   if(bmp!=null){   if(!bmp.isRecycled()){   bmp.recycle();   //回收图片所占的内存   bmp=null;           System.gc();  //提醒系统及时回收   }   }   }

效果图如下：

安卓市场：http://apk.hiapk.com/html/2013/05/1468059.html?module=256&info=IWjtVg9cqVJLYg%3D%3D
N多市场：http://www.nduoa.com/apk/detail/553415

360手机助手：http://zhushou.360.cn/search/index/?kw=%E6%A0%A1%E5%9B%AD%E5%B0%8F%E5%8A%A9%E6%89%8B

百度应用：http://as.baidu.com/a/item?docid=3101724&pre=web_am_se

优亿市场（eoe)：http://www.eoemarket.com/search/apps/?keyword=%E6%A0%A1%E5%9B%AD%E5%B0%8F%E5%8A%A9%E6%89%8B