文件下载案例

文件下载 简单案例

package com.example.demo.controller;
 
import java.io.*;
import javax.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
 
@Controller
public class FileDownloadController {
    private static final int BUFFER_SIZE = 4096;
    @GetMapping("/download/{fileName:.+}")
    public void downloadFile(@PathVariable String fileName, HttpServletResponse response) throws IOException {
        // 获取文件名和路径
        String filePath = "D:\\" + fileName;
        File file = new File(filePath);
        InputStream inputStream = new FileInputStream(file);
        // 设置响应属性
        response.setContentType("application/octet-stream");
        response.setContentLength((int) file.length());
        response.setHeader("Content-Disposition", String.format("attachment; filename=\"%s\"", file.getName()));
        // 写入输出流
        OutputStream outputStream = response.getOutputStream();
        byte[] buffer = new byte[BUFFER_SIZE];
        int bytesRead = -1;
        while ((bytesRead = inputStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, bytesRead);
        }
        inputStream.close();
        outputStream.close();
    }
}

http的get请求方式，下载文件

 
import java.net.*;
import java.io.*;
 
public class Http {
    public static void main(String[] args) throws Exception {
        URL url = new URL("http://127.0.0.1:9200/download/a.txt");
        HttpURLConnection con = (HttpURLConnection) url.openConnection();
        con.setRequestMethod("GET");
 
        BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
        String inputLine;
        StringBuffer response = new StringBuffer();
 
        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
            System.out.println(inputLine);
        }
        in.close();
 
//        System.out.println(response.toString());
    }
}