Android应用开发之（你必须知道的“文件上传时显示进度的
进行大文件上传时，显示上传进度是很好的用户体验，可以有效的缓解用户急躁的情绪。今天Android IT 分享一个好的显示上传进度的解决方案。
我们用到以下两个类就可实现带进度条的文件上传：
1、CustomMultiPartEntity extends MultipartEntity,
2、HttpMultipartPost extends AsyncTask
代码如下：
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.charset.Charset;
import org.apache.http.entity.mime.HttpMultipartMode;
import org.apache.http.entity.mime.MultipartEntity;
public class CustomMultipartEntity extends MultipartEntity {
private final ProgressListener listener;
public CustomMultipartEntity(final ProgressListener listener) {
super();
this.listener = listener;
}
public CustomMultipartEntity(final HttpMultipartMode mode, final ProgressListener listener) {
super(mode);
this.listener = listener;
}
public CustomMultipartEntity(HttpMultipartMode mode, final String boundary,
final Charset charset, final ProgressListener listener) {
super(mode, boundary, charset);
this.listener = listener;
}
@Override
public void writeTo(final OutputStream outstream) throws IOException {
super.writeTo(new CountingOutputStream(outstream, this.listener));
}
public static interface ProgressListener {
void transferred(long num);
}
public static class CountingOutputStream extends FilterOutputStream {
private final ProgressListener listener;
private long transferred;
public CountingOutputStream(final OutputStream out, final ProgressListener listener) {
super(out);
this.listener = listener;
this.transferred = 0;
}
public void write(byte[] b, int off, int len) throws IOException {
out.write(b, off, len);
this.transferred += len;
this.listener.transferred(this.transferred);
}
public void write(int b) throws IOException {
out.write(b);
this.transferred++;
this.listener.transferred(this.transferred);
}
}
}
该类计算写入的字节数，我们需要在实现ProgressListener中的trasnfered()方法，更行进度条
public class HttpMultipartPost extends AsyncTask<HttpResponse, Integer, TypeUploadImage> {
ProgressDialogpd;
longtotalSize;
@Override
protectedvoidonPreExecute(){
pd= newProgressDialog(this);
pd.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
pd.setMessage("Uploading Picture...");
pd.setCancelable(false);
pd.show();
}
@Override
protectedTypeUploadImagedoInBackground(HttpResponse... arg0) {
HttpClienthttpClient = newDefaultHttpClient();
HttpContexthttpContext = newBasicHttpContext();
HttpPosthttpPost = newHttpPost("http://herpderp.com/UploadImage.php");
try{
CustomMultipartEntitymultipartContent = newCustomMultipartEntity(
newProgressListener() {
@Override
public void transferred(longnum){
publishProgress((int) ((num / (float) totalSize) * 100));
}
});
// We use FileBody to transfer an image
multipartContent.addPart("uploaded_file", newFileBody(
newFile(m_userSelectedImagePath)));
totalSize= multipartContent.getContentLength();
// Send it
httpPost.setEntity(multipartContent);
HttpResponseresponse = httpClient.execute(httpPost, httpContext);
String serverResponse = EntityUtils.toString(response.getEntity());
ResponseFactoryrp = newResponseFactory(serverResponse);
return(TypeImage) rp.getData();
}
catch(Exception e) {
System.out.println(e);
}
returnnull;
}
@Override
protectedvoidonProgressUpdate(Integer... progress){
pd.setProgress((int) (progress[0]));
}
@Override
protectedvoidonPostExecute(TypeUploadImageui) {
pd.dismiss();
}
}
在 transferred()函数中调用publishProgress((int) ((num / (float) totalSize) * 100));
在onProgressUpdate()实现上传进度的更新操作