private String imgurl = "";

    /***
     * 功能：长按图片保存到手机
     */
    @Override
    public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {
        super.onCreateContextMenu(menu, v, menuInfo);
        MenuItem.OnMenuItemClickListener handler = new MenuItem.OnMenuItemClickListener() {
            public boolean onMenuItemClick(MenuItem item) {
                if (item.getTitle() == "保存到手机") {
                    new SaveImage().execute(); // Android 4.0以后要使用线程来访问网络
                } else {
                    return false;
                }
                return true;
            }
        };
        if (v instanceof WebView) {
            WebView.HitTestResult result = ((WebView) v).getHitTestResult();
            if (result != null) {
                int type = result.getType();
                if (type == WebView.HitTestResult.IMAGE_TYPE || type == WebView.HitTestResult.SRC_IMAGE_ANCHOR_TYPE) {
                    imgurl = result.getExtra();
                    menu.setHeaderTitle("提示");
                    menu.add(0, v.getId(), 0, "保存到手机").setOnMenuItemClickListener(handler);
                }
            }
        }
    }

    /***
     * 功能：用线程保存图片
     * 
     * @author wangyp
     * 
     */
    private class SaveImage extends AsyncTask<String, Void, String> {
        @Override
        protected String doInBackground(String... params) {
            String result = "";
            try {
                String sdcard = Environment.getExternalStorageDirectory().toString();
                File file = new File(sdcard + "/Download");
                if (!file.exists()) {
                    file.mkdirs();
                }
                int idx = imgurl.lastIndexOf(".");
                String ext = imgurl.substring(idx);
                file = new File(sdcard + "/Download/" + new Date().getTime() + ext);
                InputStream inputStream = null;
                URL url = new URL(imgurl);
                HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                conn.setRequestMethod("GET");
                conn.setConnectTimeout(20000);
                if (conn.getResponseCode() == 200) {
                    inputStream = conn.getInputStream();
                }
                byte[] buffer = new byte[4096];
                int len = 0;
                FileOutputStream outStream = new FileOutputStream(file);
                while ((len = inputStream.read(buffer)) != -1) {
                    outStream.write(buffer, 0, len);
                }
                outStream.close();
                result = "图片已保存至：" + file.getAbsolutePath();
            } catch (Exception e) {
                result = "保存失败！" + e.getLocalizedMessage();
            }
            return result;
        }

        @Override
        protected void onPostExecute(String result) {
            MsgBox("提示", result);
        }
    }