webview实现文件下载的功能

WebView控制调用相应的WEB页面进行展示。当碰到页面有下载链接的时候，点击上去是一点反应都没有的。原来是因为WebView默认没有开启文件下载的功能，如果要实现文件下载的功能，需要设置WebView的DownloadListener，通过实现自己的DownloadListener来实现文件的下载。具体操作如下：

1、设置WebView的DownloadListener：

webView.setDownloadListener(new MyWebViewDownLoadListener());

2、实现MyWebViewDownLoadListener这个类，具体可以如下这样：

[java]
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private class MyWebViewDownLoadListener implements DownloadListener{

@Override
public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimetype,
long contentLength) {
Log.i("tag", "url="+url);
Log.i("tag", "userAgent="+userAgent);
Log.i("tag", "contentDisposition="+contentDisposition);
Log.i("tag", "mimetype="+mimetype);
Log.i("tag", "contentLength="+contentLength);
Uri uri = Uri.parse(url);
Intent intent = new Intent(Intent.ACTION_VIEW, uri);
startActivity(intent);
}
}

private class MyWebViewDownLoadListener implements DownloadListener{

@Override
public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimetype,
long contentLength) {
Log.i("tag", "url="+url);
Log.i("tag", "userAgent="+userAgent);
Log.i("tag", "contentDisposition="+contentDisposition);
Log.i("tag", "mimetype="+mimetype);
Log.i("tag", "contentLength="+contentLength);
Uri uri = Uri.parse(url);
Intent intent = new Intent(Intent.ACTION_VIEW, uri);
startActivity(intent);
}
}

这只是调用系统中已经内置的浏览器进行下载，还没有WebView本身进行的文件下载，不过，这也基本上满足我们的应用场景了。

我在项目中的运用

项目要求这样：

1，需要使用WebView加载一个网页；

2，网页中有文件下载的链接，点击后需要下载文件到SDcard；

3，然后自动打开文件；

下面是具体解决办法

第一步，对WebView进行一系列设置。

[java]
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WebView webview=(WebView)layout.findViewById(R.id.webview);
webview.getSettings().setJavaScriptEnabled(true);
webview.setWebChromeClient(new MyWebChromeClient());
webview.requestFocus();
// webview.loadUrl("file:///android_asset/risktest.html");

webview.loadUrl(jcrs_sub.get(position).addr);
// 设置web视图客户端

webview.setWebViewClient(new MyWebViewClient());
webview.setDownloadListener(new MyWebViewDownLoadListener());

//内部类
public class MyWebViewClient extends WebViewClient {
// 如果页面中链接，如果希望点击链接继续在当前browser中响应，

// 而不是新开Android的系统browser中响应该链接，必须覆盖 webview的WebViewClient对象。

public boolean shouldOverviewUrlLoading(WebView view, String url) {
L.i("shouldOverviewUrlLoading");
view.loadUrl(url);
return true;
}

public void onPageStarted(WebView view, String url, Bitmap favicon) {
L.i("onPageStarted");
showProgress();
}

public void onPageFinished(WebView view, String url) {
L.i("onPageFinished");
closeProgress();
}

public void onReceivedError(WebView view, int errorCode,
String description, String failingUrl) {
L.i("onReceivedError");
closeProgress();
}
}

// 如果不做任何处理，浏览网页，点击系统“Back”键，整个Browser会调用finish()而结束自身，

// 如果希望浏览的网 页回退而不是推出浏览器，需要在当前Activity中处理并消费掉该Back事件。

public boolean onKeyDown(int keyCode, KeyEvent event) {
// if((keyCode==KeyEvent.KEYCODE_BACK)&&webview.canGoBack()){

// webview.goBack();
// return true;

// }
return false;
}

WebView webview=(WebView)layout.findViewById(R.id.webview);
webview.getSettings().setJavaScriptEnabled(true);
webview.setWebChromeClient(new MyWebChromeClient());
webview.requestFocus();
//				webview.loadUrl("file:///android_asset/risktest.html");
webview.loadUrl(jcrs_sub.get(position).addr);
// 设置web视图客户端
webview.setWebViewClient(new MyWebViewClient());
webview.setDownloadListener(new MyWebViewDownLoadListener());

//内部类
public class MyWebViewClient extends WebViewClient {
// 如果页面中链接，如果希望点击链接继续在当前browser中响应，
// 而不是新开Android的系统browser中响应该链接，必须覆盖 webview的WebViewClient对象。
public boolean shouldOverviewUrlLoading(WebView view, String url) {
L.i("shouldOverviewUrlLoading");
view.loadUrl(url);
return true;
}

public void onPageStarted(WebView view, String url, Bitmap favicon) {
L.i("onPageStarted");
showProgress();
}

public void onPageFinished(WebView view, String url) {
L.i("onPageFinished");
closeProgress();
}

public void onReceivedError(WebView view, int errorCode,
String description, String failingUrl) {
L.i("onReceivedError");
closeProgress();
}
}

// 如果不做任何处理，浏览网页，点击系统“Back”键，整个Browser会调用finish()而结束自身，
// 如果希望浏览的网 页回退而不是推出浏览器，需要在当前Activity中处理并消费掉该Back事件。
public boolean onKeyDown(int keyCode, KeyEvent event) {
// if((keyCode==KeyEvent.KEYCODE_BACK)&&webview.canGoBack()){
// webview.goBack();
// return true;
// }
return false;
}

第二步，起线程开始下载文件。

[java]
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//内部类
private class MyWebViewDownLoadListener implements DownloadListener {

@Override
public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimetype,
long contentLength) {
if(!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
Toast t=Toast.makeText(mContext, "需要SD卡。", Toast.LENGTH_LONG);
t.setGravity(Gravity.CENTER, 0, 0);
t.show();
return;
}
DownloaderTask task=new DownloaderTask();
task.execute(url);
}

}
//内部类
private class DownloaderTask extends AsyncTask<String, Void, String> {

public DownloaderTask() {
}

@Override
protected String doInBackground(String... params) {
// TODO Auto-generated method stub

String url=params[0];
// Log.i("tag", "url="+url);

String fileName=url.substring(url.lastIndexOf("/")+1);
fileName=URLDecoder.decode(fileName);
Log.i("tag", "fileName="+fileName);

File directory=Environment.getExternalStorageDirectory();
File file=new File(directory,fileName);
if(file.exists()){
Log.i("tag", "The file has already exists.");
return fileName;
}
try {
HttpClient client = new DefaultHttpClient();
// client.getParams().setIntParameter("http.socket.timeout",3000);//设置超时

HttpGet get = new HttpGet(url);
HttpResponse response = client.execute(get);
if(HttpStatus.SC_OK==response.getStatusLine().getStatusCode()){
HttpEntity entity = response.getEntity();
InputStream input = entity.getContent();

writeToSDCard(fileName,input);

input.close();
// entity.consumeContent();

return fileName;
}else{
return null;
}
} catch (Exception e) {
e.printStackTrace();
return null;
}
}

@Override
protected void onCancelled() {
// TODO Auto-generated method stub

super.onCancelled();
}

@Override
protected void onPostExecute(String result) {
// TODO Auto-generated method stub

super.onPostExecute(result);
closeProgressDialog();
if(result==null){
Toast t=Toast.makeText(mContext, "连接错误！请稍后再试！", Toast.LENGTH_LONG);
t.setGravity(Gravity.CENTER, 0, 0);
t.show();
return;
}

Toast t=Toast.makeText(mContext, "已保存到SD卡。", Toast.LENGTH_LONG);
t.setGravity(Gravity.CENTER, 0, 0);
t.show();
File directory=Environment.getExternalStorageDirectory();
File file=new File(directory,result);
Log.i("tag", "Path="+file.getAbsolutePath());

Intent intent = getFileIntent(file);

startActivity(intent);

}

@Override
protected void onPreExecute() {
// TODO Auto-generated method stub

super.onPreExecute();
showProgressDialog();
}

@Override
protected void onProgressUpdate(Void... values) {
// TODO Auto-generated method stub

super.onProgressUpdate(values);
}

}

//内部类
private class MyWebViewDownLoadListener implements DownloadListener {

@Override
public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimetype,
long contentLength) {
if(!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
Toast t=Toast.makeText(mContext, "需要SD卡。", Toast.LENGTH_LONG);
t.setGravity(Gravity.CENTER, 0, 0);
t.show();
return;
}
DownloaderTask task=new DownloaderTask();
task.execute(url);
}

}
//内部类
private class DownloaderTask extends AsyncTask<String, Void, String> {

public DownloaderTask() {
}

@Override
protected String doInBackground(String... params) {
// TODO Auto-generated method stub
String url=params[0];
//			Log.i("tag", "url="+url);
String fileName=url.substring(url.lastIndexOf("/")+1);
fileName=URLDecoder.decode(fileName);
Log.i("tag", "fileName="+fileName);

File directory=Environment.getExternalStorageDirectory();
File file=new File(directory,fileName);
if(file.exists()){
Log.i("tag", "The file has already exists.");
return fileName;
}
try {
HttpClient client = new DefaultHttpClient();
//                client.getParams().setIntParameter("http.socket.timeout",3000);//设置超时
HttpGet get = new HttpGet(url);
HttpResponse response = client.execute(get);
if(HttpStatus.SC_OK==response.getStatusLine().getStatusCode()){
HttpEntity entity = response.getEntity();
InputStream input = entity.getContent();

writeToSDCard(fileName,input);

input.close();
//					entity.consumeContent();
return fileName;
}else{
return null;
}
} catch (Exception e) {
e.printStackTrace();
return null;
}
}

@Override
protected void onCancelled() {
// TODO Auto-generated method stub
super.onCancelled();
}

@Override
protected void onPostExecute(String result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
closeProgressDialog();
if(result==null){
Toast t=Toast.makeText(mContext, "连接错误！请稍后再试！", Toast.LENGTH_LONG);
t.setGravity(Gravity.CENTER, 0, 0);
t.show();
return;
}

Toast t=Toast.makeText(mContext, "已保存到SD卡。", Toast.LENGTH_LONG);
t.setGravity(Gravity.CENTER, 0, 0);
t.show();
File directory=Environment.getExternalStorageDirectory();
File file=new File(directory,result);
Log.i("tag", "Path="+file.getAbsolutePath());

Intent intent = getFileIntent(file);

startActivity(intent);

}

@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
showProgressDialog();
}

@Override
protected void onProgressUpdate(Void... values) {
// TODO Auto-generated method stub
super.onProgressUpdate(values);
}

}

第三步，实现一些工具方法。

[java]
view plaincopyprint?

<SPAN style="FONT-FAMILY: Helvetica, Tahoma, Arial, sans-serif">private ProgressDialog mDialog;
private void showProgressDialog(){
if(mDialog==null){
mDialog = new ProgressDialog(mContext);
mDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);//设置风格为圆形进度条

mDialog.setMessage("正在加载 ，请等待...");
mDialog.setIndeterminate(false);//设置进度条是否为不明确

mDialog.setCancelable(true);//设置进度条是否可以按退回键取消

mDialog.setCanceledOnTouchOutside(false);
mDialog.setOnDismissListener(new OnDismissListener() {

@Override
public void onDismiss(DialogInterface dialog) {
// TODO Auto-generated method stub

mDialog=null;
}
});
mDialog.show();

}
}
private void closeProgressDialog(){
if(mDialog!=null){
mDialog.dismiss();
mDialog=null;
}
}
public Intent getFileIntent(File file){
// Uri uri = Uri.parse("http://m.ql18.com.cn/hpf10/1.pdf");

Uri uri = Uri.fromFile(file);
String type = getMIMEType(file);
Log.i("tag", "type="+type);
Intent intent = new Intent("android.intent.action.VIEW");
intent.addCategory("android.intent.category.DEFAULT");
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.setDataAndType(uri, type);
return intent;
}

public void writeToSDCard(String fileName,InputStream input){

if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
File directory=Environment.getExternalStorageDirectory();
File file=new File(directory,fileName);
// if(file.exists()){

// Log.i("tag", "The file has already exists.");

// return;

// }
try {
FileOutputStream fos = new FileOutputStream(file);
byte[] b = new byte[2048];
int j = 0;
while ((j = input.read(b)) != -1) {
fos.write(b, 0, j);
}
fos.flush();
fos.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block

e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block

e.printStackTrace();
}
}else{
Log.i("tag", "NO SDCard.");
}
}

private String getMIMEType(File f){
String type="";
String fName=f.getName();
/* 取得扩展名 */
String end=fName.substring(fName.lastIndexOf(".")+1,fName.length()).toLowerCase();

/* 依扩展名的类型决定MimeType */
if(end.equals("pdf")){
type = "application/pdf";//

}
else if(end.equals("m4a")||end.equals("mp3")||end.equals("mid")||
end.equals("xmf")||end.equals("ogg")||end.equals("wav")){
type = "audio/*";
}
else if(end.equals("3gp")||end.equals("mp4")){
type = "video/*";
}
else if(end.equals("jpg")||end.equals("gif")||end.equals("png")||
end.equals("jpeg")||end.equals("bmp")){
type = "image/*";
}
else if(end.equals("apk")){
/* android.permission.INSTALL_PACKAGES */
type = "application/vnd.android.package-archive";
}
// else if(end.equals("pptx")||end.equals("ppt")){

// type = "application/vnd.ms-powerpoint";

// }else if(end.equals("docx")||end.equals("doc")){

// type = "application/vnd.ms-word";

// }else if(end.equals("xlsx")||end.equals("xls")){

// type = "application/vnd.ms-excel";

// }
else{
// /*如果无法直接打开，就跳出软件列表给用户选择 */

type="*/*";
}
return type;
} </SPAN>

<span style="font-family:Helvetica, Tahoma, Arial, sans-serif;"><span>private ProgressDialog mDialog;
private void showProgressDialog(){
if(mDialog==null){
mDialog = new ProgressDialog(mContext);
mDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);//设置风格为圆形进度条
mDialog.setMessage("正在加载 ，请等待...");
mDialog.setIndeterminate(false);//设置进度条是否为不明确
mDialog.setCancelable(true);//设置进度条是否可以按退回键取消
mDialog.setCanceledOnTouchOutside(false);
mDialog.setOnDismissListener(new OnDismissListener() {

@Override
public void onDismiss(DialogInterface dialog) {
// TODO Auto-generated method stub
mDialog=null;
}
});
mDialog.show();

}
}
private void closeProgressDialog(){
if(mDialog!=null){
mDialog.dismiss();
mDialog=null;
}
}
public Intent getFileIntent(File file){
//		 Uri uri = Uri.parse("http://m.ql18.com.cn/hpf10/1.pdf");
Uri uri = Uri.fromFile(file);
String type = getMIMEType(file);
Log.i("tag", "type="+type);
Intent intent = new Intent("android.intent.action.VIEW");
intent.addCategory("android.intent.category.DEFAULT");
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.setDataAndType(uri, type);
return intent;
}

public void writeToSDCard(String fileName,InputStream input){

if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
File directory=Environment.getExternalStorageDirectory();
File file=new File(directory,fileName);
//			if(file.exists()){
//				Log.i("tag", "The file has already exists.");
//				return;
//			}
try {
FileOutputStream fos = new FileOutputStream(file);
byte[] b = new byte[2048];
int j = 0;
while ((j = input.read(b)) != -1) {
fos.write(b, 0, j);
}
fos.flush();
fos.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}else{
Log.i("tag", "NO SDCard.");
}
}

private String getMIMEType(File f){
String type="";
String fName=f.getName();
/* 取得扩展名 */
String end=fName.substring(fName.lastIndexOf(".")+1,fName.length()).toLowerCase();

/* 依扩展名的类型决定MimeType */
if(end.equals("pdf")){
type = "application/pdf";//
}
else if(end.equals("m4a")||end.equals("mp3")||end.equals("mid")||
end.equals("xmf")||end.equals("ogg")||end.equals("wav")){
type = "audio/*";
}
else if(end.equals("3gp")||end.equals("mp4")){
type = "video/*";
}
else if(end.equals("jpg")||end.equals("gif")||end.equals("png")||
end.equals("jpeg")||end.equals("bmp")){
type = "image/*";
}
else if(end.equals("apk")){
/* android.permission.INSTALL_PACKAGES */
type = "application/vnd.android.package-archive";
}
//      else if(end.equals("pptx")||end.equals("ppt")){
//    	  type = "application/vnd.ms-powerpoint";
//      }else if(end.equals("docx")||end.equals("doc")){
//    	  type = "application/vnd.ms-word";
//      }else if(end.equals("xlsx")||end.equals("xls")){
//    	  type = "application/vnd.ms-excel";
//      }
else{
//    	  /*如果无法直接打开，就跳出软件列表给用户选择 */
type="*/*";
}
return type;
}   </span></span>

[java]
view plaincopyprint?

<SPAN style="FONT-FAMILY: Helvetica, Tahoma, Arial, sans-serif">转自：<A href="http://gundumw100.iteye.com/blog/1338645">http://gundumw100.iteye.com/blog/1338645</A>
</SPAN>

<span style="font-family:Helvetica, Tahoma, Arial, sans-serif;"><span>转自：</span><a target=_blank href="http://gundumw100.iteye.com/blog/1338645"><span>http://gundumw100.iteye.com/blog/1338645</span></a>
</span>