Android学习之查看网络图片

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

private EditText etImageUrl;
    private ImageView ivImage;

/**控件初始化*/
    private void init() {
        ivImage = (ImageView) findViewById(R.id.ivImage);
        etImageUrl = (EditText) findViewById(R.id.etImageUrl);
        
    }

private Handler handler = new Handler(){
        public void handleMessage(android.os.Message msg) {
            //对接收到的消息进行处理
//            Looper.prepare();
            switch (msg.what) {
            case SHOW_IMAGE:
                Bitmap bitmap = (Bitmap) msg.obj;//将OS流中的Object强制转换为Bitmap对象
                ivImage.setImageBitmap(bitmap);
                
                Toast toast = Toast.makeText(MainActivity.this, "图片加载成功", Toast.LENGTH_SHORT);
                toast.setGravity(0, 0, 100);
                toast.show();
                break;

            default:
                break;
            }
        };
    };

public void showImage(View view){//若在xml文件中使用onClick（）属性，则其方法格式必须为  方法名（View view）
        final String path = etImageUrl.getText().toString();
        if (TextUtils.isEmpty(path)) {
            Toast.makeText(MainActivity.this, "图片路径不能为空", Toast.LENGTH_SHORT).show();
        } else {
            new Thread(){
                public void run(){
                    
                    //链接服务器，请求获取图片
                    try {
                        URL url = new URL(path);
                        //发出http请求
                        HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
                        httpURLConnection.setRequestMethod("GET");
                        //设置链接超时时间
                        httpURLConnection.setConnectTimeout(5000);
                        
                        int responsecode = httpURLConnection.getResponseCode();//获取响应码
                        if (responsecode == 200) {
                            InputStream is = httpURLConnection.getInputStream();//获取输入流
                            Bitmap bitmap = BitmapFactory.decodeStream(is);
                            
                            //2.告诉主线程，帮我更新界面，内容是Bitmap
                            Message msg = new Message();
                            msg.what = SHOW_IMAGE;
                            msg.obj = bitmap;
                            handler.sendMessage(msg);
                        }else{
                            Toast toast = Toast.makeText(MainActivity.this, "图片加载失败", Toast.LENGTH_SHORT);
                            toast.setGravity(0, 0, 100);
                            toast.show();
                        }
                        
                    } catch (MalformedURLException e) {
                        e.printStackTrace();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }.start();//务必启动线程
        }
    }