如何使用JProgressBar显示文件复制进度？

Question

我正在开发一个通过网络传输文件的项目，我想合并一个 JProgressBar 来显示文件传输过程中的进度，但我需要这方面的帮助。

Answer 1

您可能会发现 ProgressMonitorInputStream 最简单，但如果这对您来说还不够，请查看其源代码以准确获取您想要的内容。

 InputStream in = new BufferedInputStream(
                     new ProgressMonitorInputStream(
                              parentComponent,
                              "Reading " + fileName,
                              new FileInputStream(fileName)
                     )
                  );

要使用不同的传输方法，请用适当的流替换 FileInputStream。

Answer 2

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLConnection;
import javax.swing.JProgressBar;

....

public OutputStream loadFile(URL remoteFile, JProgressBar progress) throws IOException
{
    URLConnection connection = remoteFile.openConnection(); //connect to remote file
    InputStream inputStream = connection.getInputStream(); //get stream to read file

    int length = connection.getContentLength(); //find out how long the file is, any good webserver should provide this info
    int current = 0;

    progress.setMaximum(length); //we're going to get this many bytes
    progress.setValue(0); //we've gotten 0 bytes so far

    ByteArrayOutputStream out = new ByteArrayOutputStream(); //create our output steam to build the file here

    byte[] buffer = new byte[1024];
    int bytesRead = 0;

    while((bytesRead = inputStream.read(buffer)) != -1) //keep filling the buffer until we get to the end of the file 
    {   
        out.write(buffer, current, bytesRead); //write the buffer to the file offset = current, length = bytesRead
        current += bytesRead; //we've progressed a little so update current
        progress.setValue(current); //tell progress how far we are
    }
    inputStream.close(); //close our stream

    return out;
}

我很确定这会起作用。

Answer 3

听起来您应该使用 SwingWorker，如此核心 Java 技术提示中所述。 另请参见使用 Swing 工作线程。

Answer 4

好吧这里是JProgressBar的教程，也许是会有帮助的。