在开发中WebView不会主动去下载文件，但webView提供了下载文件的的接口
webView.setOnDownloadListener(new OnDownloadListener(){
})；
第一种：实现Java代码下载
其中有一个回调方法返回要下载文件的url，我们可以使用该url在native中实现网络下载
class MyDownloadStart implements DownloadListener{
@Override
public void onDownloadStart(String url, String userAgent,
String contentDisposition, String mimetype, long contentLength) {
// TODO Auto-generated method stub
//调用自己的下载方式
// new HttpThread(url).start();
}
} 第二种：使用系统下载器下载
class MyDownloadStart implements DownloadListener{
@Override
public void onDownloadStart(String url, String userAgent,
String contentDisposition, String mimetype, long contentLength){
AppUtils.LogD(mimetype);
// download file
DownloadManager downloadManager = ((DownloadManager) activity
.getSystemService(Activity.DOWNLOAD_SERVICE));
Request request = new Request(Uri.parse(url));
// set request header, 如session等 www.2cto.com
request.addRequestHeader("Accept",
"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
request.addRequestHeader("Accept-Language", "en-us,en;q=0.5");
request.addRequestHeader("Accept-Encoding", "gzip, deflate");
request.addRequestHeader("Accept-Charset",
"ISO-8859-1,utf-8;q=0.7,*;q=0.7");
request.addRequestHeader("Cache-Control", "max-age=0");
String host = "";
try {
host = new URL(url).getHost();
} catch (MalformedURLException e) {
e.printStackTrace();
}
String cookieStr = CookieManager.getInstance().getCookie(host);
if (!AppUtils.isEmpty(cookieStr)) {
request.addRequestHeader("Cookie", cookieStr + "; AcSe=0");
}
// generate filename dynamically
String fileName = contentDisposition.replaceFirst(
"attachment; filename=", "");
request.setDestinationInExternalPublicDir(
Environment.DIRECTORY_DOWNLOADS, fileName);
downloadManager.enqueue(request);
});第三种：使用默认浏览器下载
将获得到的url转为 uri，然后调用系统的浏览器去下载，这种方式可以看见文件下载进度条
class MyDownloadStart implements DownloadListener{
@Override
public void onDownloadStart(String url, String userAgent,
String contentDisposition, String mimetype, long contentLength) {
// TODO Auto-generated method stub
//调用系统浏览器下载
Uri uri = Uri.parse(url);
Intent intent = new Intent(Intent.ACTION_VIEW, uri);
startActivity(intent);
}
}
