你可以使用Java的URL类和URLConnection类来下载文件到本地指定文件夹。以下是一个简单的示例：

```java

import java.io.*;

import java.net.URL;

import java.net.URLConnection;

public class FileDownloader {

public static void main(String[] args) {

String fileUrl = "-to-download.txt";

String saveDir = "/path/to/save/directory/";

try {

URL url = new URL(fileUrl);

URLConnection conn = url.openConnection();

InputStream inputStream = conn.getInputStream();

// 获取文件名

String fileName = getFileName(fileUrl);

// 在保存目录中创建文件

File outputFile = new File(saveDir + "/" + fileName);

FileOutputStream outputStream=

new FileOutputStream(outputFile);

byte[] buffer=new byte[1024];

    int len;

              while((len=inputStream.read(buffer))!=-1){

                outputStream.write(buffer,0,len);

}

            inputStream.close();

               outputStream.close();

System.out.println("Downloaded successfully!");

} catch (IOException e) {

e.printStackTrace();