Java 如何下载文件并在本地获取路径位置

我有一个网址，即。 如果我将其粘贴到选项卡上并按enter键，则文件（SubAngle.exe）将被下载并保存在下载文件夹中。这是手动过程。但可以使用java代码完成。 我使用文件名SubAngle.exe编写了获取绝对路径的代码

要求：-在下载URL文件的帮助下，验证文件是否已下载并返回文件的绝对路径

where  locfile is "http://downloadplugins.verify.com/Windows/SubAngle.exe"  

  public String downloadAndVerifyFile(String locfile) {
     File fileLocation = new File(locfile); 
     File fileLocation1 = new File(fileLocation.getName());
     String fileLocationPath = null;
     if(fileLocation.exists()){
      fileLocationPath = fileLocation1.getAbsolutePath();

     }
     else{
         throw new FileNotFoundException("File with name "+locFile+" may not exits at the location");
     }
     return fileLocationPath;
}

---

从URL下载文件的代码

import java.net.*;
import java.io.*;

public class DownloadFile {
    public static void main(String[] args) throws IOException {
        InputStream in = null;
        FileOutputStream out = null;
        try {
            // URL("http://downloadplugins.verify.com/Windows/SubAngle.exe");
            System.out.println("Starting download");
            long t1 = System.currentTimeMillis();
            URL url = new URL(args[0]);
            // Open the input and out files for the streams
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            in = conn.getInputStream();
            out = new FileOutputStream("YourFile.exe");
            // Read data into buffer and then write to the output file
            byte[] buffer = new byte[8192];
            int bytesRead;
            while ((bytesRead = in.read(buffer)) != -1) {
                out.write(buffer, 0, bytesRead);
            }
            long t2 = System.currentTimeMillis();
            System.out.println("Time for download & save file in millis:"+(t2-t1));
        } catch (Exception e) {
            // Display or throw the error
            System.out.println("Erorr while execting the program: "
                    + e.getMessage());
        } finally {
            // Close the resources correctly
            if (in != null) {
                in.close();
            }
            if (out != null) {
                out.close();
            }
        }

    }

}

正确配置fileName的值，以了解文件的存储位置。 资料来源：

源已被修改为用http URL替换本地文件

import java.net.*;
import java.io.*;

public class DownloadFile {
    public static void main(String[] args) throws IOException {
        InputStream in = null;
        FileOutputStream out = null;
        try {
            // URL("http://downloadplugins.verify.com/Windows/SubAngle.exe");
            System.out.println("Starting download");
            long t1 = System.currentTimeMillis();
            URL url = new URL(args[0]);
            // Open the input and out files for the streams
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            in = conn.getInputStream();
            out = new FileOutputStream("YourFile.exe");
            // Read data into buffer and then write to the output file
            byte[] buffer = new byte[8192];
            int bytesRead;
            while ((bytesRead = in.read(buffer)) != -1) {
                out.write(buffer, 0, bytesRead);
            }
            long t2 = System.currentTimeMillis();
            System.out.println("Time for download & save file in millis:"+(t2-t1));
        } catch (Exception e) {
            // Display or throw the error
            System.out.println("Erorr while execting the program: "
                    + e.getMessage());
        } finally {
            // Close the resources correctly
            if (in != null) {
                in.close();
            }
            if (out != null) {
                out.close();
            }
        }

    }

}

输出：

java下载文件

开始下载

---

下载和保存文件的时间（毫秒）：100184

从URL下载文件的代码

import java.net.*;
import java.io.*;

public class DownloadFile {
    public static void main(String[] args) throws IOException {
        InputStream in = null;
        FileOutputStream out = null;
        try {
            // URL("http://downloadplugins.verify.com/Windows/SubAngle.exe");
            System.out.println("Starting download");
            long t1 = System.currentTimeMillis();
            URL url = new URL(args[0]);
            // Open the input and out files for the streams
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            in = conn.getInputStream();
            out = new FileOutputStream("YourFile.exe");
            // Read data into buffer and then write to the output file
            byte[] buffer = new byte[8192];
            int bytesRead;
            while ((bytesRead = in.read(buffer)) != -1) {
                out.write(buffer, 0, bytesRead);
            }
            long t2 = System.currentTimeMillis();
            System.out.println("Time for download & save file in millis:"+(t2-t1));
        } catch (Exception e) {
            // Display or throw the error
            System.out.println("Erorr while execting the program: "
                    + e.getMessage());
        } finally {
            // Close the resources correctly
            if (in != null) {
                in.close();
            }
            if (out != null) {
                out.close();
            }
        }

    }

}

正确配置fileName的值，以了解文件的存储位置。 资料来源：

源已被修改为用http URL替换本地文件

import java.net.*;
import java.io.*;

public class DownloadFile {
    public static void main(String[] args) throws IOException {
        InputStream in = null;
        FileOutputStream out = null;
        try {
            // URL("http://downloadplugins.verify.com/Windows/SubAngle.exe");
            System.out.println("Starting download");
            long t1 = System.currentTimeMillis();
            URL url = new URL(args[0]);
            // Open the input and out files for the streams
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            in = conn.getInputStream();
            out = new FileOutputStream("YourFile.exe");
            // Read data into buffer and then write to the output file
            byte[] buffer = new byte[8192];
            int bytesRead;
            while ((bytesRead = in.read(buffer)) != -1) {
                out.write(buffer, 0, bytesRead);
            }
            long t2 = System.currentTimeMillis();
            System.out.println("Time for download & save file in millis:"+(t2-t1));
        } catch (Exception e) {
            // Display or throw the error
            System.out.println("Erorr while execting the program: "
                    + e.getMessage());
        } finally {
            // Close the resources correctly
            if (in != null) {
                in.close();
            }
            if (out != null) {
                out.close();
            }
        }

    }

}

输出：

java下载文件

开始下载

---

下载并以毫秒为单位保存文件的时间：100184不要编写这么庞大的代码，而是使用Apache的commons.io 试试这个：

URL ipURL = new URL("inputURL");
File opFile = new File("outputFile");
FileUtils.copyURLToFile(ipURL, opFile);

---

不要编写这么庞大的代码，而是使用Apache的commons.io 试试这个：

URL ipURL = new URL("inputURL");
File opFile = new File("outputFile");
FileUtils.copyURLToFile(ipURL, opFile);

---

我使用的简单而通用的功能：

import org.apache.commons.io.FileUtils;

public static void downLoadFile(String fromFile, String toFile) throws MalformedURLException, IOException {
        try {
            FileUtils.copyURLToFile(new URL(fromFile), new File(toFile), 60000, 60000);

        } catch (FileNotFoundException e) {
            e.printStackTrace();
            System.out.println("exception on: downLoadFile() function: " + e.getMessage());
        }
    }

---

我使用的简单而通用的功能：

import org.apache.commons.io.FileUtils;

public static void downLoadFile(String fromFile, String toFile) throws MalformedURLException, IOException {
        try {
            FileUtils.copyURLToFile(new URL(fromFile), new File(toFile), 60000, 60000);

        } catch (FileNotFoundException e) {
            e.printStackTrace();
            System.out.println("exception on: downLoadFile() function: " + e.getMessage());
        }
    }

---

不，你应该有一个本地路径，它反映了你磁盘上的一个位置，比如C:\Users\{your user name}\Downloadsrelated:可能重复的否，你应该有一个本地路径，它反映了你磁盘上的一个位置，比如C:\Users\{your user name}\Downloadsrelated:如果你复制粘贴，可能重复的，至少要使用OP提供的url和文件，还要注意你的链接断开了，这可能是打字错误。我在“下载”中提供了工作链接，如果文件大小大于1 GB怎么办？它可以处理，因为我们正在写入大小为1024字节的字节数组。它不需要1 GB RAM，但您只需要1 GB磁盘空间。如果您遇到1 GB文件大小的问题，请告诉我。out.write（）之后是Add out.flush（）说真的，你为什么要将文件读入ByteArrayOutputStream？显然，如果文件太大，这会失败。更不用说它毫无意义且效率低下。如果你复制粘贴，至少要使用OP提供的url和文件，还要注意你的链接断开了，这可能是打字错误。我在“中提供了工作链接”下载“如果文件大小大于1GB怎么办？它可以处理，因为我们正在编写大小为1024字节的字节数组。它不需要1GB的RAM，但您只需要1GB的磁盘空间。如果您遇到1 GB文件大小的问题，请告诉我。在out.write（）之后添加out.flush（）。认真地说，为什么要将文件读入ByteArrayOutputStream？显然，如果文件太大，这将失败。更不用说它毫无意义，效率低下。