这里做个记录，通过此次问题的解决，弄清POST同时传文件及参数时，底层到底是怎么组成，文件流及参数是怎么分隔组成，及分隔符如何写入流。
好，废话不多说，直接上代码，此代码配置好自己参数可直接调试，无需引入更多包。
1 package com.hhb;
2 import java.io.*;
3 import java.net.HttpURLConnection;
4 import java.net.URL;
5 import java.net.URLConnection;
6 public class upoad {
7 public static void main(String[] args) {
8 System.out.println("上传开始");
9 //要上传的图片
10 String uploadFilePaths = "D:\\loadFile.jpg";
11 //请求上传图片API地址
12 String actionUrl = "https://localhost/api/File/UploadFile";
13
14 //参数 Rax 随机数(10位数)。TimeUtc 时间戳(秒级别)
15 String Scope = "TrackReceipt";
16 String Rax = "5tqczr48id";
17 String TimeUtc = "1677722176";
18 String token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJodHRwOi8vc2NoZW1hcy5taWNyb3NvZnQuY29tL3dzLzIwMDgvMDYvaWRlbnRpdHkvY2xhaW1zL3ByaW1hcnlzaWQiOiIzYTA5YjIxMC04OGE3LWE4MDItY2Y1Mi1iOGI2YzhjNDE1OTMiLCJodHRwOi8vc2NoZW1hcy54bWxzb2FwLm9yZy93cy8yMDA1LzA1L2lkZW50aXR5L2NsYWltcy9zaWQiOiIwOGRhZjgyYy01M2Q4LTQxZTQtODAzOC1kMmUyMDkyMmNhM2MiLCJuYmYiOjE2Nzc3MTk3NDQsImV4cCI6MTY4MDMxMTc0NCwiaXNzIjoib2NlbG90IiwiYXVkIjoiaGNkIn0.erl5opo0tie-MVmEMQYYoaGkIs-LbbftYREoHAfyzJg";
19 //调用
20 String rel = uploadFile(actionUrl, uploadFilePaths, Scope, Rax, TimeUtc, token);
21 System.out.println("返回结果：" + rel);
22 }
23
24 /**
25 * 多文件上传的方法
26 *
27 * @param actionUrl：上传的路径
28 * @param uploadFilePaths：需要上传的文件路径，数组
29 * @return
30 */
31 @SuppressWarnings("finally")
32 public static String uploadFile(String actionUrl, String uploadFilePaths, String Scope
33 , String Rax, String TimeUtc, String token) {
34 String end = "\r\n";
35 String twoHyphens = "--";
36 String boundary = "*****";
37
38 DataOutputStream ds = null;
39 InputStream inputStream = null;
40 InputStreamReader inputStreamReader = null;
41 BufferedReader reader = null;
42 StringBuffer resultBuffer = new StringBuffer();
43 String tempLine = null;
44 token = "Bearer " + token;
45
46 String uploadFile = uploadFilePaths;
47 String filename = uploadFile.substring(uploadFile.lastIndexOf("\\") + 1);
48
49 try {
50 // 统一资源
51 URL url = new URL(actionUrl);
52 // 连接类的父类，抽象类
53 URLConnection urlConnection = url.openConnection();
54 // http的连接类
55 HttpURLConnection httpURLConnection = (HttpURLConnection) urlConnection;
56 // 设置是否从httpUrlConnection读入，默认情况下是true;
57 httpURLConnection.setDoInput(true);
58 // 设置是否向httpUrlConnection输出
59 httpURLConnection.setDoOutput(true);
60 // Post 请求不能使用缓存
61 httpURLConnection.setUseCaches(false);
62 // 设定请求的方法，默认是GET
63 httpURLConnection.setRequestMethod("POST");
64 // 设置字符编码连接参数
65 httpURLConnection.setRequestProperty("Connection", "Keep-Alive");
66 // 设置字符编码
67 httpURLConnection.setRequestProperty("Charset", "UTF-8");
68 // 设置请求内容类型
69 httpURLConnection.setRequestProperty("Authorization", token);
70
71 httpURLConnection.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
72
73 // 设置DataOutputStream
74 ds = new DataOutputStream(httpURLConnection.getOutputStream());
75
76 //封装键值对数据一
77 ds.writeBytes(twoHyphens + boundary + end);
78 ds.writeBytes("Content-Disposition: form-data; name=\"" + "Scope" + "\"");
79 ds.writeBytes(end);
80 // ds.writeBytes("Content-Type: " + "text/plain");
81 // ds.writeBytes(end);
82 // ds.writeBytes("Content-Lenght: " + ("" + Scope).length());
83 // ds.writeBytes(end);
84 ds.writeBytes(end);
85 ds.writeBytes("" + Scope);
86 ds.writeBytes(end);
87
88
89 //封装键值对数据三
90 ds.writeBytes(twoHyphens + boundary + end);
91 ds.writeBytes("Content-Disposition: form-data; name=\"" + "Rax" + "\"");
92 ds.writeBytes(end);
93 ds.writeBytes(end);
94 ds.writeBytes("" + Rax);
95 ds.writeBytes(end);
96
97 //封装键值对数据四
98 ds.writeBytes(twoHyphens + boundary + end);
99 ds.writeBytes("Content-Disposition: form-data; name=\"" + "TimeUtc" + "\"");
100 ds.writeBytes(end);
101 ds.writeBytes(end);
102 ds.writeBytes("" + TimeUtc);
103 ds.writeBytes(end);
104
105 //封装图片数据
106 ds.writeBytes(twoHyphens + boundary + end);
107 ds.writeBytes("Content-Disposition: form-data; " + "name=\"File\";filename=\"" + filename
108 + "\"" + end);
109 ds.writeBytes("Content-Type: " + "image/jpeg" + end);
110 //ds.writeBytes("Content-Lenght: "+file.length()+ end);
111 ds.writeBytes(end);
112 FileInputStream fStream = new FileInputStream(uploadFile);
113 int bufferSize = 1024;
114 byte[] buffer = new byte[bufferSize];
115 int length = -1;
116 while ((length = fStream.read(buffer)) != -1) {
117 ds.write(buffer, 0, length);
118 }
119 ds.writeBytes(end);
120 /* close streams */
121 fStream.close();
122 //输入结束
123 ds.writeBytes(twoHyphens + boundary + twoHyphens + end);
124 /* close streams */
125 ds.flush();
126 if (httpURLConnection.getResponseCode() >= 300) {
127 throw new Exception(
128 "HTTP Request is not success, Response code is " + httpURLConnection.getResponseCode());
129 }
130 if (httpURLConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {
131 inputStream = httpURLConnection.getInputStream();
132 inputStreamReader = new InputStreamReader(inputStream);
133 reader = new BufferedReader(inputStreamReader);
134 tempLine = null;
135 resultBuffer = new StringBuffer();
136 while ((tempLine = reader.readLine()) != null) {
137 resultBuffer.append(tempLine);
138 resultBuffer.append("\n");
139 }
140 }
141 } catch (Exception e) {
142 e.printStackTrace();
143 } finally {
144 if (ds != null) {
145 try {
146 ds.close();
147 } catch (IOException e) {
148 // TODO Auto-generated catch block
149 e.printStackTrace();
150 }
151 }
152 if (reader != null) {
153 try {
154 reader.close();
155 } catch (IOException e) {
156 // TODO Auto-generated catch block
157 e.printStackTrace();
158 }
159 }
160 if (inputStreamReader != null) {
161 try {
162 inputStreamReader.close();
163 } catch (IOException e) {
164 // TODO Auto-generated catch block
165 e.printStackTrace();
166 }
167 }
168 if (inputStream != null) {
169 try {
170 inputStream.close();
171 } catch (IOException e) {
172 // TODO Auto-generated catch block
173 e.printStackTrace();
174 }
175 }
176 return resultBuffer.toString();
177 }
178 }
179 }
参考:http://www.manongjc.com/detail/26-ibpgtovosforqma.html标签：end,String,form,Java,writeBytes,null,data,ds,httpURLConnection From： https://www.cnblogs.com/tjdk/p/17172258.html
https://blog.csdn.net/AP0906424/article/details/108998071