阿冰教你一步一步做Android新闻客户端（二）两种异步线程加载图片的方法

哈哈哈抱着没人看的心态随便写，直接上代码，各位看官看注释

一种Thread  一种AsyncTask 先不说用框架 

public class ImageLoader {
    private ImageView mImageView;
    private String mUrl;

//Thread明显很low 还需要handler来传递消息，好累T T

    android.os.Handler mHandler = new android.os.Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            if (mImageView.getTag().equals(mUrl))
            mImageView.setImageBitmap((Bitmap)msg.obj);
        }
    };

    public void showImageByThread(ImageView imageView, final String url) {
        mImageView =imageView;
        mUrl = url;//对传过来的imageView 和url进行映射下 映射成mImageView 和mUrl 哈哈 这样就可以使用咯（还为了避免程序逻辑顺序错误，和viewholder的机制差不多）
        new Thread() {
            @Override
            public void run() {
                super.run();
                Bitmap bitmap = getBitmapFromURL(url);
                Message message = Message.obtain();
                message.obj = bitmap;
                mHandler.sendMessage(message);
            }
        }.start();

    }

    //创建从URL获取Bitmap的放方法，还是老一套 很多try/catch 看着就心累，这么多就为了获取Bitmap
    public Bitmap getBitmapFromURL(String stringUrl) {

        Bitmap bitmap;
        BufferedInputStream bis = null;

        URL url1 = null;
        try {
            url1 = new URL(stringUrl);
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }

        HttpURLConnection connection = null;
        try {
            connection = (HttpURLConnection) url1.openConnection();
        } catch (IOException e) {
            e.printStackTrace();
        }
        try {
            bis = new BufferedInputStream(connection.getInputStream());

            bitmap = BitmapFactory.decodeStream(bis);
            connection.disconnect();
            return bitmap;
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                bis.close();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }return null;
        }
//========================================================我是无耻的分割线========请无视我==============下面是AsyncTask获取网络图片=================================================高能警报======================



    public void showImageByAsyncTask (ImageView imageView,final String mUrl){
                    new MyIconSyncTask(imageView,mUrl).execute(mUrl);

    }
　　　　//三个参数传进来的String url ，过程返回值不要写Void ， 结果返回值 Bitmap
    class MyIconSyncTask extends AsyncTask<String,Void,Bitmap> {
            private ImageView mImageView;
            private String mUrl;
        public MyIconSyncTask(ImageView imageView,String url){  //写个构造方法是为了映射下得到的Imageview 和String url
            mUrl = url;
            mImageView = imageView;
        }
        @Override
        protected Bitmap doInBackground(String... params) {

            return getBitmapFromURL(params[0]);             //把耗时操作交给doInBackground 
        }

        @Override
        protected void onPostExecute(Bitmap bitmap) {    //通过onPostExecute和UI线程交互 完全不用handler 妈妈再也不用担心我用handler了 ，再这个方法里imageview设置bitmap
            super.onPostExecute(bitmap);
            if (mImageView.getTag().equals(mUrl)) {
                mImageView.setImageBitmap(bitmap);
            }
        }
    }
    }