socket模拟http请求，socket模拟http文件上传

向右看齐 2023-10-08 23:11 44阅读 0赞

后端接收3个参数： file、remotePath、time

@PostMapping("/upload")
            public String upload(@RequestParam("file") MultipartFile file, String remotePath, String time) {
                System.out.println(file);
                System.out.println(remotePath);
                System.out.println(time);
                return "上传成功";
            }

前端准备一个form表单

本地新建一个名为：myfile.txt的文本文件，txt文件内容：123456

发送一个form表单请求

![d176869c575c4dc0a5ffe92491c854c0.png][]

请求后抓包如下：

POST http://localhost:8080/upload HTTP/1.1
    Host: localhost:8080
    Content-Length: 358
    Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryQSFobk9lz8ATC9Ax
    
    ------WebKitFormBoundaryQSFobk9lz8ATC9Ax
    Content-Disposition: form-data; name="file"; filename="myfile.txt"
    
    123456
    ------WebKitFormBoundaryQSFobk9lz8ATC9Ax
    Content-Disposition: form-data; name="remotePath"
    
    123
    ------WebKitFormBoundaryQSFobk9lz8ATC9Ax
    Content-Disposition: form-data; name="time"
    
    456
    ------WebKitFormBoundaryQSFobk9lz8ATC9Ax--

然后 socket 模拟这个报文即可。

\----WebKitFormBoundaryQSFobk9lz8ATC9Ax 这个字符串使用uuid模拟即可，保证唯一就行。

封装成http客户端工具

package com.study;
    
    import java.io.*;
    import java.net.Socket;
    import java.net.URI;
    import java.nio.charset.StandardCharsets;
    import java.util.HashMap;
    import java.util.Map;
    import java.util.UUID;
    
    /**
     * Socket模拟Http客户端
     * @author 
     * @date 2023/3/31 18:05
     */
    public class SocketHttpClient {
    
        public static void main(String[] args) throws Exception {
            String url = "http://localhost:8080/upload";
            // 要上传的文件
            Map<String, String> files = new HashMap<>();
            // key:文件名  value:文件绝对路径
            files.put("myfile.txt", "D:/myfile.txt");
            Map<String, String> params = new HashMap<>();
            // 请求参数：name=vaue
            params.put("remotePath", "123");
            params.put("time", "456");
    
            String sendPost = sendPost(url, null, null);
            System.out.println(sendPost);
        }
    
        /**
         * 模拟POST请求
         * @param url    请求路径
         * @param files  上传的文件
         * @param params 请求参数
         * @author 
         * @date 2023/3/31 17:42
         */
        public static String sendPost(String url, Map<String, String> files, Map<String, String> params) {
            Socket socket = null;
            InputStream inputStream = null;
            OutputStream outputStream = null;
            try {
                URI uri = new URI(url);
                // 要连接的服务端IP地址和端口
                String host = uri.getHost();
                int port = uri.getPort();
                if (port == -1) {
                    port = 80;
                }
                // 与服务端建立连接
                socket = new Socket(host, port);
                socket.setSoTimeout(5000);//读超时
                // 建立好连接后，从socket中获取输入流
                inputStream = socket.getInputStream();
                // 建立好连接后，从socket中获取输出流
                outputStream = socket.getOutputStream();
    
                //获取http模拟报文
                byte[] httpSocket = getHttpSocket(url, files, params);
                outputStream.write(httpSocket);
                outputStream.flush();
    
                //这里需要延时一段时间,等待文件上传完成，再发送终止符
                Thread.sleep(1000);
                socket.shutdownOutput();// 单向关闭输出流，发送流的终止符-1。
    
                byte[] buf = new byte[1024];
                int len;
                StringBuilder sb = new StringBuilder();
                //只有当客户端关闭它的输出流的时候，服务端才能取得结尾的-1
                while ((len = inputStream.read(buf)) != -1) {
                    // 注意指定编码格式，发送方和接收方一定要统一，建议使用UTF-8
                    sb.append(new String(buf, 0, len, StandardCharsets.UTF_8));
                }
                String result = sb.toString();
                if (result != null && result.indexOf("\r\n\r\n") != -1) {
                    return result.substring(result.indexOf("\r\n\r\n") + 4);
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                try {
                    if (inputStream != null) {
                        inputStream.close();
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
                try {
                    if (outputStream != null) {
                        outputStream.close();
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
                try {
                    if (socket != null) {
                        socket.close();
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return null;
        }
    
        /**
         * 拼接http报文
         * @author 
         * @date 2023/3/31 17:47
         */
        private static byte[] getHttpSocket(String url, Map<String, String> files, Map<String, String> params) throws Exception {
            URI uri = new URI(url);
            int port = uri.getPort();
            if (port == -1) {
                port = 80;
            }
            String boundary = UUID.randomUUID().toString().replace("-", "");
            // 请求体
            byte[] body = getBody(boundary, files, params);
            String host = uri.getHost() + ":" + port;
            ByteArrayOutputStream http = new ByteArrayOutputStream();
            http.write(("POST " + url + " HTTP/1.1\r\n").getBytes(StandardCharsets.UTF_8));
            http.write(("Content-Type: multipart/form-data; boundary=" + boundary + "\r\n").getBytes(StandardCharsets.UTF_8));
            http.write(("Host: " + host + "\r\n").getBytes(StandardCharsets.UTF_8));
            http.write(("Content-Length: " + body.length + "\r\n").getBytes(StandardCharsets.UTF_8));
            http.write("\r\n".getBytes(StandardCharsets.UTF_8));
            http.write(body);
            return http.toByteArray();
        }
    
        /**
         * 拼接http请求体内容
         * @author 
         * @date 2023/3/31 17:47
         */
        private static byte[] getBody(String boundary, Map<String, String> files, Map<String, String> params) throws Exception {
            // 定义存放 body 内容的缓冲区
            ByteArrayOutputStream body = new ByteArrayOutputStream();
    
            // 拼接文件部分
            if (files != null) {
                for (Map.Entry<String, String> entry : files.entrySet()) {
                    body.write(("--" + boundary + "\r\n").getBytes(StandardCharsets.UTF_8));
                    // name="file" 是表单name属性，注意要改成跟自己的一致。
                    body.write(("Content-Disposition: form-data; name=\"file\"; filename=\"" + entry.getKey() + "\"\r\n")
                            .getBytes(StandardCharsets.UTF_8));
                    body.write("\r\n".getBytes(StandardCharsets.UTF_8));
                    // 文件绝对路径
                    String path = entry.getValue();
                    byte[] buf = new byte[1024];
                    int len;
                    FileInputStream fis = null;
                    try {
                        // 将文件内容，写入缓冲区
                        fis = new FileInputStream(path);
                        while ((len = fis.read(buf)) != -1) {
                            body.write(buf, 0, len);
                        }
                        body.write("\r\n".getBytes(StandardCharsets.UTF_8));
                    } catch (Exception e) {
                        throw e;
                    } finally {
                        if (fis != null) {
                            try {
                                fis.close();
                            } catch (IOException e) {
                                e.printStackTrace();
                            }
                        }
                    }
                }
            }
    
            // 拼接普通表单参数部分
            if (params != null) {
                for (Map.Entry<String, String> entry : params.entrySet()) {
                    body.write(("--" + boundary + "\r\n").getBytes(StandardCharsets.UTF_8));
                    // 参数名
                    body.write(("Content-Disposition: form-data; name=\"" + entry.getKey() + "\"\r\n")
                            .getBytes(StandardCharsets.UTF_8));
                    body.write("\r\n".getBytes(StandardCharsets.UTF_8));
                    // 参数值
                    body.write(entry.getValue().getBytes(StandardCharsets.UTF_8));
                    body.write("\r\n".getBytes(StandardCharsets.UTF_8));
                }
            }
            if (files != null || params != null) {
                // 结束标记
                body.write(("--" + boundary + "--").getBytes(StandardCharsets.UTF_8));
                body.write("\r\n".getBytes(StandardCharsets.UTF_8));
            }
            return body.toByteArray();
        }
    }

[d176869c575c4dc0a5ffe92491c854c0.png]: https://img-blog.csdnimg.cn/d176869c575c4dc0a5ffe92491c854c0.png