java如何上传文件到指定服务器

在 Java 中可以使用 Apache HttpClient 或者 HttpURLConnection 来实现文件上传到指定服务器，以下是两种方法的示例：

使用 Apache HttpClient:

import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpPost; import org.apache.http.entity.ContentType; import org.apache.http.entity.mime.MultipartEntityBuilder; import org.apache.http.impl.client.HttpClients;  import java.io.File; import java.io.IOException;  public class FileUploader {      public static void main(String[] args) {         HttpClient httpClient = HttpClients.createDefault();         HttpPost httpPost = new HttpPost("http://example.com/upload");          File file = new File("path/to/file.txt");          HttpEntity entity = MultipartEntityBuilder.create()                 .addBinaryBody("file", file, ContentType.DEFAULT_BINARY, file.getName())                 .build();          httpPost.setEntity(entity);          try {             HttpResponse response = httpClient.execute(httpPost);             System.out.println(response.getStatusLine());         } catch (IOException e) {             e.printStackTrace();         }     } } 

使用 HttpURLConnection:

import java.io.DataOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.net.HttpURLConnection; import java.net.URL;  public class FileUploader {      public static void main(String[] args) {         String url = "http://example.com/upload";         String fileName = "path/to/file.txt";          try {             URL serverUrl = new URL(url);             HttpURLConnection connection = (HttpURLConnection) serverUrl.openConnection();             connection.setRequestMethod("POST");             connection.setDoOutput(true);             connection.setRequestProperty("Content-Type", "multipart/form-data");              File file = new File(fileName);             FileInputStream fileInputStream = new FileInputStream(file);             DataOutputStream outputStream = new DataOutputStream(connection.getOutputStream());              byte[] buffer = new byte[4096];             int bytesRead;             while ((bytesRead = fileInputStream.read(buffer)) != -1) {                 outputStream.write(buffer, 0, bytesRead);             }              fileInputStream.close();             outputStream.flush();             outputStream.close();              int responseCode = connection.getResponseCode();             System.out.println("Server response code: " + responseCode);         } catch (IOException e) {             e.printStackTrace();         }     } } 

以上示例代码演示了如何使用 Apache HttpClient 和 HttpURLConnection 来上传文件到指定服务器。在实际应用中，需要根据服务器的接口要求和认证方式进行适当的配置。