POST简略

2015-07-14

简单描述:

post的数据在 request Payload 内, 因此,Request Headers 里面带有一个 boundary 属性,服务器收到 post 请求之后,通过 boundary 将参数从 Payload 中分离出来。

params = body.split(boundary)

唯一需要注意的是,CRLF(回车换行符)的使用。HTTP协议对CRLF的内容分割要求还是略严的。

Request Headers

Content-Type:multipart/form-data; boundary=----WebKitFormBoundarydKY7YrWhI3bdiNYz

Request Payload

--{boundary}
Content-Disposition: form-data; name="{name1}"

{value1}
--{boundary}
Content-Disposition: form-data; name="{name2}"

{value2}
--{boundary}
Content-Disposition: form-data; name="{file_name1}"; filename="xxx.png"
Content-Type: image/png

0x120x12...

--{boundary}--

示例说明

    <form method="post" enctype="multipart/form-data">
        <div><input type="checkbox" name="k1" checked value="1"/><label>1</label></div>
        <div><input type="checkbox" name="k1" checked value="2"/><label>2</label></div>
        <div><input type="file" name="pic"/></div>
    </form>

提交格式:

headers

Content-Type:multipart/form-data; boundary=----WebKitFormBoundarydKY7YrWhI3bdiNYz

payload:

------WebKitFormBoundarydKY7YrWhI3bdiNYz
Content-Disposition: form-data; name="k1"

1
------WebKitFormBoundarydKY7YrWhI3bdiNYz
Content-Disposition: form-data; name="k2"

2
------WebKitFormBoundarydKY7YrWhI3bdiNYz
Content-Disposition: form-data; name="{file_name1}"; filename="xxx.png"
Content-Type: image/png

....(这里是图片字节).....

------WebKitFormBoundarydKY7YrWhI3bdiNYz--

示例代码

    import java.io.*;
    import java.net.HttpURLConnection;
    import java.net.MalformedURLException;
    import java.net.ProtocolException;
    import java.net.URL;
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;

    public class Post {

        private String BOUNDARY = "-------1234567890987654321";
        private String CRLF = "\r\n";
        private Map<String, List<String>> keyValues = new HashMap<>();
        private Map<String, List<String>> pngs = new HashMap<>();

        //添加字符串键值对
        public void keyValue(String key, String value) {
            if (!keyValues.containsKey(key)) {
                keyValues.put(key, new ArrayList<>());
            }
            keyValues.get(key).add(value);
        }

        //添加png图片
        public void png(String key, String pngFilePath) {
            if (!pngs.containsKey(key)) {
                pngs.put(key, new ArrayList<>());
            }
            pngs.get(key).add(pngFilePath);
        }

        public String post(String urlString) {
            try {
                URL url = new URL(urlString);
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                connection.setConnectTimeout(5000);
                connection.setReadTimeout(10000);
                connection.setDoOutput(true);
                connection.setDoInput(true);
                connection.setUseCaches(false);
                connection.setRequestMethod("POST");
                connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + BOUNDARY);

                OutputStream out = new DataOutputStream(connection.getOutputStream());

                for (Map.Entry<String, List<String>> kv : keyValues.entrySet()) {
                    for (String value : kv.getValue()) {
                        String item = new StringBuilder("--").append(BOUNDARY).append(CRLF)
                                .append("Content-Disposition: form-data; name=").append(kv.getKey()).append(CRLF)
                                .append(CRLF)
                                .append(value).append(CRLF)
                                .toString();
                        out.write(item.getBytes());
                    }
                }

                //添加png图片
                for (Map.Entry<String, List<String>> kv : pngs.entrySet()) {
                    for (String value : kv.getValue()) {
                        String item = new StringBuilder("--").append(BOUNDARY).append(CRLF)
                                .append("Content-Disposition: form-data; name=").append(kv.getKey()).append(";").append("filename=").append(value).append(CRLF)
                                .append("Content-Type: image/png").append(CRLF)
                                .append(CRLF)
                                .toString();
                        out.write(item.getBytes());

                        //写入文件内容
                        FileInputStream fileInputStream = new FileInputStream(value);
                        byte[] bytes = new byte[512];
                        int count;
                        while ((count = fileInputStream.read(bytes)) != -1) {
                            out.write(bytes, 0, count);
                        }
                        out.write(CRLF.getBytes());
                    }
                }
                out.write(("--" + BOUNDARY + "--" + CRLF).getBytes());//结尾

                out.flush();
                out.close();

                StringBuffer response = new StringBuffer();
                BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
                String line;
                while ((line = reader.readLine()) != null) {
                    response.append(line).append("\n");
                }
                reader.close();
                return response.toString();

            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (ProtocolException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return "";
        }

        public static void main(String[] args) throws IOException {

            Post post = new Post();
            post.keyValue("k1", "a");
            post.keyValue("k2", "b");
            post.png("pic", "/home/xe/Pictures/1.png");
            post.png("pic", "/home/xe/Pictures/1.png");

            String response = post.post("http://127.0.0.1:3000/upload");
            System.out.println(response);
        }
    }


文档信息 by XiaoPingYuan

版权声明:自由转载-非商用-非衍生-保持署名。发表日期:2015-07-14 by XiaoPingYuan(https://xesam.github.io/)