mCurrentWebView.setDownloadListener(new DownloadListener() {

    @Override

    public void onDownloadStart(final String url, String userAgent, String contentDisposition, String mimetype, long contentLength) {

    　　// TODO 实现下载逻辑

        Log.e("onDownloadStart", "url===" + url + "---userAgent=" + userAgent + "---contentDisposition=" + contentDisposition + "---mimetype=" + mimetype + "---contentLength=" + contentLength);

　　}

});

HttpParams params = new BasicHttpParams();

HttpConnectionParams.setConnectionTimeout(params, 5 * 1000);

HttpConnectionParams.setSoTimeout(params, 5 * 1000);

HttpGet httpGet = new HttpGet(url);

try {

    File file = new File(Environment.getExternalStorageDirectory(), fileName);

    if (!file.exists()) {

        file.createNewFile();

    } else {

　　　　 boolean flag = file.delete();

　　　　 if (flag) {

        　　file.createNewFile();

　　　　 } else {

　　　　 　　return;

　　　　 }
　　}

    RandomAccessFile randomFile = new RandomAccessFile(file, "rw");

    HttpResponse response = new DefaultHttpClient(params).execute(httpGet);

    HttpEntity entity = response.getEntity();

    InputStream in = entity.getContent();

    randomFile.seek(randomFile.length());

    byte[] buffer = new byte[1024];

    int lenght = 0;

    while ((lenght = in.read(buffer)) > 0) {

        randomFile.write(buffer, 0, lenght);

        DebugTraceTool.debugTraceE(this, "file length == " + randomFile.length());

    }

    randomFile.close();

    httpGet.abort();

} catch (Exception e) {

    e.printStackTrace();

}