android 自定义进度条下载apk并更新

下载文件使用子线程，更新到UI上使用handler，效果如图：

主要代码如下：

    public void downFile(final String httpUrl,final Handler handler) {        new Thread(new Runnable() {            @Override            public void run() {                try {                    File file = null;                    URL url = new URL(httpUrl);                    HttpURLConnection connection = (HttpURLConnection) url.openConnection();                    connection.setRequestMethod("GET");                    connection.setConnectTimeout(5000);                    FileOutputStream fileOutputStream = null;                    InputStream inputStream;                    if (connection.getResponseCode() == 200) {                        inputStream = connection.getInputStream();                        if (inputStream != null) {                            file = getFile(httpUrl);                            delFile(file.getAbsolutePath());                            fileOutputStream = new FileOutputStream(file);                            byte[] buffer = new byte[1024];                            int length = 0;                            int total = 0;                            int max = connection.getContentLength();                            while ((length = inputStream.read(buffer)) != -1) {                                fileOutputStream.write(buffer, 0, length);                                total += length;                                Message msg = handler.obtainMessage();                                msg.what = LoadingActivity.DOWNLOADING;                                msg.arg1 = (int)(total*100/max);                                handler.sendMessage(msg);                            }                            fileOutputStream.close();                            fileOutputStream.flush();                        }                        inputStream.close();                    }                    Message message = handler.obtainMessage();                    message.what = LoadingActivity.DOWNLOAD_COMPLETE;                    handler.sendMessage(message);                    installApk(file);                } catch (MalformedURLException e) {                    e.printStackTrace();                } catch (IOException e) {                    e.printStackTrace();                }            }        }).start();    }    /**     * 根据传过来url创建文件     *      */    private  File getFile(String url) {        File files = new File(Environment.getExternalStorageDirectory().getAbsoluteFile(), getFilePath(url));        return files;    }    /**     * 截取出url后面的apk的文件名     *      * @param url     * @return     */    private  String getFilePath(String url) {        return url.substring(url.lastIndexOf("/"), url.length());    }    /***     * 删除临时存放的文件     *      * @param url     *            文件路径     */    private  void delFile(String url) {        File myFile = new File(url);        if (myFile.exists()) {            myFile.delete();        }    }    /**     * 安装APK     */    private void installApk(File file) {        Intent intent = new Intent(Intent.ACTION_VIEW);        intent.setDataAndType(Uri.fromFile(file), "application/vnd.android.package-archive");        context.startActivity(intent);        context.finish();    }

然后在handler中处理UI：

    private Handler mHandler = new Handler() {        public void handleMessage(Message msg) {            int what = msg.what;            switch(what) {            case DOWNLOAD_COMPLETE:                break;            case DOWNLOADING:                int percent = (int)msg.arg1;                progressBar.setProgress(percent);                break;            }        };    };

下面重点说下自定义的进度条

    public RoundProgressBar(Context context) {        this(context, null);    }    public RoundProgressBar(Context context, AttributeSet attrs) {        this(context, attrs, 0);    }    public RoundProgressBar(Context context, AttributeSet attrs, int defStyle) {        super(context, attrs, defStyle);        paint = new Paint();        TypedArray mTypedArray = context.obtainStyledAttributes(attrs,                R.styleable.RoundProgressBar);        roundColor = mTypedArray.getColor(R.styleable.RoundProgressBar_roundColor, Color.RED);        roundProgressColor = mTypedArray.getColor(R.styleable.RoundProgressBar_roundProgressColor, Color.GREEN);        textColor = mTypedArray.getColor(R.styleable.RoundProgressBar_textColor, Color.GREEN);        textSize = mTypedArray.getDimension(R.styleable.RoundProgressBar_textSize, 15);        roundWidth = mTypedArray.getDimension(R.styleable.RoundProgressBar_roundWidth, 5);        max = mTypedArray.getInteger(R.styleable.RoundProgressBar_max, 100);        textIsDisplayable = mTypedArray.getBoolean(R.styleable.RoundProgressBar_textIsDisplayable, true);        style = mTypedArray.getInt(R.styleable.RoundProgressBar_style, 0);        mTypedArray.recycle();    }    @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        int centre = getWidth()/2;         int radius = (int) (centre - roundWidth/2);         paint.setColor(roundColor);         paint.setStyle(Paint.Style.STROKE);         paint.setStrokeWidth(roundWidth);         paint.setAntiAlias(true);         canvas.drawCircle(centre, centre, radius, paint);        paint.setStrokeWidth(0);         paint.setColor(textColor);        paint.setTextSize(textSize);        paint.setTypeface(Typeface.DEFAULT_BOLD);         int percent = (int)(((float)progress / (float)max) * 100);          float textWidth = paint.measureText(percent + "%");          if(textIsDisplayable && percent != 0 && style == STROKE){            canvas.drawText(percent + "%", centre - textWidth / 2, centre + textSize/2, paint);         }        paint.setStrokeWidth(roundWidth);         paint.setColor(roundProgressColor);         RectF oval = new RectF(centre - radius, centre - radius, centre                + radius, centre + radius);          switch (style) {        case STROKE:{            paint.setStyle(Paint.Style.STROKE);            canvas.drawArc(oval, 0, 360 * progress / max, false, paint);            break;        }        case FILL:{            paint.setStyle(Paint.Style.FILL_AND_STROKE);            if(progress !=0)                canvas.drawArc(oval, 0, 360 * progress / max, true, paint);              break;        }        }    }    public synchronized int getMax() {        return max;    }    public synchronized void setMax(int max) {        if(max < 0){            throw new IllegalArgumentException("max not less than 0");        }        this.max = max;    }    public synchronized int getProgress() {        return progress;    }    public synchronized void setProgress(int progress) {        if(progress < 0){            throw new IllegalArgumentException("progress not less than 0");        }        if(progress > max){            progress = max;        }        if(progress <= max){            this.progress = progress;            postInvalidate();        }    }    public int getCricleColor() {        return roundColor;    }    public void setCricleColor(int cricleColor) {        this.roundColor = cricleColor;    }    public int getCricleProgressColor() {        return roundProgressColor;    }    public void setCricleProgressColor(int cricleProgressColor) {        this.roundProgressColor = cricleProgressColor;    }    public int getTextColor() {        return textColor;    }    public void setTextColor(int textColor) {        this.textColor = textColor;    }    public float getTextSize() {        return textSize;    }    public void setTextSize(float textSize) {        this.textSize = textSize;    }    public float getRoundWidth() {        return roundWidth;    }    public void setRoundWidth(float roundWidth) {        this.roundWidth = roundWidth;    }

类RoundProgressBar继承于view，基本属性在attr.xml中去定义，而我们需要关注的是setProgress(),因为封装的RoundProgressBar，我们都是通过调用setProgress()方法去刷新进度，在这个方法中也是不断调用postInvalidate()方法，即不断去draw，接下来就是我们的重头戏onDraw()了：
我们可以将此view分为三部分，
1. 圆形的圈(空心的)；
2. 中间的文字加百分比符号，统一为字符串；
3. 弧形的圈。
通过这样分析，就简单啦～
自定义view少不了跟android的画笔paint和canvas打交道。

paint.setColor(roundColor); paint.setStyle(Paint.Style.STROKE); paint.setStrokeWidth(roundWidth); paint.setAntiAlias(true); canvas.drawCircle(centre, centre, radius, paint);

其中的canvas.drawCircle(float cx, float cy, float radius, Paint paint)表示以(cx,cy) 为中心，radius为半径画一个圆。paint.setStrokeWidth(roundWidth)表示画的圆的外围的宽度。
这样我们的空心圆就出来了～
接下来就是画中间的字符串：

paint.setStrokeWidth(0); paint.setColor(textColor);paint.setTextSize(textSize);paint.setTypeface(Typeface.DEFAULT_BOLD); int percent = (int)(((float)progress / (float)max) * 100);  float textWidth = paint.measureText(percent + "%"); canvas.drawText(percent + "%", centre - textWidth / 2, centre + textSize/2, paint);  

其中canvas.(String text, float x, float y, Paint paint)表示以坐标(x,y)为中心，画出文字text,这里我们使用paint.measureText(text)方法，使得画出的文字能居中。
最后就是画弧度了：

paint.setStrokeWidth(roundWidth); paint.setColor(roundProgressColor); RectF oval = new RectF(centre - radius, centre - radius, centre+radius, centre + radius);  paint.setStyle(Paint.Style.STROKE);canvas.drawArc(oval, 0, 360 * progress / max, false, paint);

canvas.drawArc(RectF oval, float startAngle, float sweepAngle, boolean useCenter, Paint paint)表示用长方形画出sweepAngle角度的弧度。这里我试了设置画笔Paint.Style.STROKE和Paint.Style.FILL_AND_STROKE效果一样的，然后就是长方形的四个坐标，找了半天没找到笔，只能口述了～假设有个中心点center,那左上角left的物理坐标就是centre-left，以此类推～

好了，自定义进度条下载apk并更新已讲解完，自己也对自定义view有更好的理解了，哈哈～