网络文件下载与上传

要下载网络文件，首先需要获取网络文件的URL。可以使用Java中的URL类来创建URL对象，并通过openStream方法获取网络文件的输入流。然后，我们可以使用Java File中的FileOutputStream类将网络文件的输入流写入到本地文件中，实现文件的下载。

下面是一个简单的示例代码，用于下载网络文件：

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;

public class FileDownloader {
    public static void downloadFile(String fileUrl, String savePath) throws IOException {
        URL url = new URL(fileUrl);
        try (InputStream inputStream = url.openStream();
             FileOutputStream outputStream = new FileOutputStream(savePath)) {
            byte[] buffer = new byte[4096];
            int bytesRead;
            while ((bytesRead = inputStream.read(buffer)) != -1) {
                outputStream.write(buffer, 0, bytesRead);
            }
        }
    }

    public static void main(String[] args) {
        String fileUrl = "
        String savePath = "C:/path/to/save/example.txt";
        try {
            downloadFile(fileUrl, savePath);
            System.out.println("File downloaded successfully.");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

2.2 上传文件到服务器
要上传文件到服务器，首先需要获取服务器的URL和文件的本地路径。然后，我们可以使用Java File中的FileInputStream类将本地文件的输入流读取出来，并通过HTTP请求将文件发送到服务器。

下面是一个简单的示例代码，用于上传文件到服务器：

 

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;

public class FileUploader {
    public static void uploadFile(String fileUrl, String serverUrl) throws IOException {
        URL url = new URL(serverUrl);
        File file = new File(fileUrl);
        try (InputStream inputStream = new FileInputStream(file);
             OutputStream outputStream = url.openConnection().getOutputStream()) {
            byte[] buffer = new byte[4096];
            int bytesRead;
            while ((bytesRead = inputStream.read(buffer)) != -1) {
                outputStream.write(buffer, 0, bytesRead);
            }
        }
    }

    public static void main(String[] args) {
        String fileUrl = "C:/path/to/upload/example.txt";
        String serverUrl = "
        try {
            uploadFile(fileUrl, serverUrl);
            System.out.println("File uploaded successfully.");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

2.3 删除网络文件
要删除网络文件，我们可以使用Java中的URL类来创建URL对象，并通过URLConnection类的实例来发送HTTP DELETE请求，将要删除的文件的URL作为请求的目标。

下面是一个简单的示例代码，用于删除网络文件：

 

import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;

public class FileDeleter {
    public static void deleteFile(String fileUrl) throws IOException {
        URL url = new URL(fileUrl);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setRequestMethod("DELETE");
        int responseCode = connection.getResponseCode();
        if (responseCode == HttpURLConnection.HTTP_OK) {
            System.out.println("File deleted successfully.");
        } else {
            System.out.println("Failed to delete file. Response code: " + responseCode);
        }
    }

    public static void main(String[] args) {
        String fileUrl = "
        try {
            deleteFile(fileUrl);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}