android小知识

 

android多点触摸缩放图片

[java]  view plain copy

   /**
    * 自定义触摸事件
    * @author tian
    *
    */
 rivate class TouchListener implements OnTouchListener{
  private PointF startPoint = new PointF();
     private Matrix matrix = new Matrix();
     private Matrix currentMaritx = new Matrix();

     private int mode = 0;//用于标记模式
     private static final int DRAG = 1;//拖动
     private static final int ZOOM = 2;//放大
     private float startDis = 0;
     private PointF midPoint;//中心点
 @Override
 public boolean onTouch(View v, MotionEvent event) {
     // TODO Auto-generated method stub
     switch (event.getAction() & MotionEvent.ACTION_MASK)
     {
         case MotionEvent.ACTION_DOWN:
             mode = DRAG;
             currentMaritx.set(imageView.getImageMatrix());//记录ImageView当期的移动位置
             startPoint.set(event.getX(),event.getY());//开始点
             break;
         case MotionEvent.ACTION_MOVE://移动事件
             if (mode == DRAG) {//图片拖动事件
                 float dx = event.getX() - startPoint.x;//x轴移动距离
                 float dy = event.getY() - startPoint.y;
                 matrix.set(currentMaritx);//在当前的位置基础上移动
                 matrix.postTranslate(dx, dy);
                 } else if(mode == ZOOM)
                     {//图片放大事件
                         float endDis = distance(event);//结束距离
                         if(endDis > 10f){
                             float scale = endDis / startDis;//放大倍数
                             matrix.set(currentMaritx);
                             matrix.postScale(scale, scale, midPoint.x, midPoint.y);
                         }
                     }
             break;
      case MotionEvent.ACTION_UP:
         mode = 0;
         break;
        //有手指离开屏幕，但屏幕还有触点(手指)
      case MotionEvent.ACTION_POINTER_UP:
         mode = 0;
         break;
        //当屏幕上已经有触点（手指）,再有一个手指压下屏幕
      case MotionEvent.ACTION_POINTER_DOWN:
         mode = ZOOM;
         startDis = distance(event);
         if(startDis > 10f){//避免手指上有两个茧
          midPoint = mid(event);
          currentMaritx.set(imageView.getImageMatrix());//记录当前的缩放倍数
         }
         break;
        }

         imageView.setImageMatrix(matrix);
         return true;
       }
     }
         /**
          * 两点之间的距离
          * @param event
          * @return
          */
         private static float distance(MotionEvent event){
          //两根线的距离
          float dx = event.getX(1) - event.getX(0);
          float dy = event.getY(1) - event.getY(0);
          return FloatMath.sqrt(dx*dx + dy*dy);
         }
         /**
          * 计算两点之间中心点的距离
          * @param event
          * @return
          */
         private static PointF mid(MotionEvent event){
          float midx = event.getX(1) + event.getX(0);
          float midy = event.getY(1) - event.getY(0);
          return new PointF(midx/2, midy/2);
         }

 

android保存图片到SD卡并以时间命名

 private void storeInSD(Bitmap bitmap1) {
         File file = new File(FILE_DIR);
                     if (!file.exists()) {
                         file.mkdir();
                     }
                     File imageFile = new File(file, FileUtils.getFileName() + ".png");
                     try {
                         imageFile.createNewFile();
                         FileOutputStream fos = new FileOutputStream(imageFile);
                         bitmap1.compress(CompressFormat.PNG, 50, fos);

                         Toast.makeText(MainActivity.this, "保存成功！", 1);

                         fos.flush();
                         fos.close();
                     } catch (FileNotFoundException e) {
                         e.printStackTrace();
                         Toast.makeText(MainActivity.this, "保存失败！", 1);
                     } catch (IOException e) {
                         // TODO Auto-generated catch block
                         e.printStackTrace();
                         Toast.makeText(MainActivity.this, "保存失败！", 1);
                     }
                 }

 public static String getCharacterAndNumber() {
         String rel="";
         SimpleDateFormat formatter = new SimpleDateFormat("yyyyMMddHHmmss");
         Date curDate = new Date(System.currentTimeMillis());
         rel = formatter.format(curDate);
         return rel;
     }

 public static String getFileName() {
         // mu
         //String fileNameRandom = getCharacterAndNumber(8);
         String fileNameRandom = getCharacterAndNumber();
         return  fileNameRandom;
     }

 

android实现自动关机代码

 private void shutdown() {
             try {
                 Process process = Runtime.getRuntime().exec("su");
                 DataOutputStream out = new DataOutputStream(
                         process.getOutputStream());
                 out.writeBytes("reboot -p\n");
                 out.writeBytes("exit\n");
                 out.flush();
             } catch (IOException e) {
                 e.printStackTrace();
             }
         }

Note:手机必须获取Root权限！！！

 

android 自定义listview无法响应点击事件OnItemClickListener

转载自: http://blog.csdn.net/qzzsunly/article/details/7824591

如果你的自定义ListViewItem中有Button或者Checkable的子类控件的话，那么默认focus是交给了子控件，而ListView的Item能被选中的基础是它能获取Focus，也就是说我们可以通过将ListView中Item中包含的所有控件的focusable属性设置为false，这样的话ListView的Item自动获得了Focus的权限，也就可以被选中了

   我们可以通过对Item Layout的根控件设置其android:descendantFocusability=”blocksDescendants”即可，这样Item Layout就屏蔽了所有子控件获取Focus的权限，不需要针对Item Layout中的每一个控件重新设置focusable属性了，如此就可以顺利的响应onItemClickListener中的onItemClick()方法了。

如何为ListView加上快速滑块，是否可以修改快速滑块图像呢？

1.android:fastScrollEnabled="true"

2.Listview组件没有提供修改快速滑块的图像的API，因此不能直接修改，需要用java的反射技术修改

 listView1 = (ListView)findViewById(R.id.listView1);
         listView1.setFastScrollEnabled(true);
         //获取FastScroller对象
         try {
             Field field = AbsListView.class.getDeclaredField("mFastScroller");
             field.setAccessible(true);
             Object obj = field.get(listView1);
             //获取FastScroller.mThumbDrable变量的Field对象
             field = field.getType().getDeclaredField("mThumbDrawable");
             field.setAccessible(true);
             //获取FastScroller.mThumbDrable的值
             Drawable drawable = (Drawable)field.get(obj);
             drawable = getResources().getDrawable(R.drawable.ic_launcher);
             field.set(obj, drawable);

         } catch (Exception e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }

运行效果：

android TextView图文混写 嵌入表情

 private void setImageText()
     {
         //根据ID获取图像的Bitmap对象
         Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
         //创建imageSpan对象
         ImageSpan imageSpan = new ImageSpan(this, bitmap);
         //创建一个SpannableString对imageSpan进行封装
         SpannableString spannableString = new SpannableString("icon哇咔咔");
         //用ImageSpan对象替换icon
         spannableString.setSpan(imageSpan, 0, 4, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
         tv_hello.setText(spannableString);
     }

彻底退出android程序的方法

 package com.cqupt.util;
 import java.util.LinkedList;
 import java.util.List;

 import android.app.Activity;
 import android.app.Application;

 public class ExitApplication extends Application {

     private List<Activity> activityList = new LinkedList();
     private static ExitApplication instance;

     private ExitApplication()
     {
     }
     //单例模式中获取唯一的ExitApplication实例
     public static ExitApplication getInstance()
     {
     if(null == instance)
     {
     instance = new ExitApplication();
     }
     return instance;

     }
     //添加Activity到容器中
     public void addActivity(Activity activity)
     {
         activityList.add(activity);
     }
     //遍历所有Activity并finish

     public void exit()
     {

         for(Activity activity : activityList)
         {
             activity.finish();
         }

         System.exit(0);

     }
     }

在每个Activity的OnCreate方法里面写上

 ExitApplication.getInstance().addActivity(this);

在要结束程序的地方：

 if (!isExit) {
                     Toast.makeText(MoreActivity.this, "再点一次退出程序", Toast.LENGTH_SHORT).show();
                     isExit = true;
                 }else{
                     ExitApplication.getInstance().exit();
                 }

转载自： http://www.yoyong.com/archives/199