怎么利用HttpURLConnection向服务器发送键值对

安卓实现通过放在数据流中OutputStream上传键值对，content请求头怎么写的

看你的服务器怎么约定，一般是post ，content-type 用 x-www-form-urlencoded

也就是post类似 name=xxx&id=xxx 这样的字符串

https://blog.csdn.net/qq_39172525/article/details/78543246，参考一下

package com.honor.web.util.tools;

import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.SocketTimeoutException;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import javax.imageio.stream.ImageInputStream;

public class HttpPostUtil {
URL url;

HttpURLConnection conn;

String boundary = "--------httppost123";

Map<String, String> textParams = new HashMap<String, String>();

Map<String, File> fileparams = new HashMap<String, File>();

DataOutputStream ds;

public HttpPostUtil(String url) throws Exception {
    this.url = new URL(url);
}

//重新设置要请求的服务器地址，即上传文件的地址。
public void setUrl(String url) throws Exception {
    this.url = new URL(url);
}

//增加一个普通字符串数据到form表单数据中
public void addTextParameter(String name, String value) {
    textParams.put(name, value);
}

//增加一个文件到form表单数据中
public void addFileParameter(String name, File value) {
    fileparams.put(name, value);
}

// 清空所有已添加的form表单数据
public void clearAllParameters() {
    textParams.clear();
    fileparams.clear();
}

// 发送数据到服务器，返回一个字节包含服务器的返回结果的数组
public byte[] send() throws Exception {
    initConnection();
    try {
        conn.connect();
    } catch (SocketTimeoutException e) {
        // something
        throw new RuntimeException();
    }
    ds = new DataOutputStream(conn.getOutputStream());
    writeFileParams();
    writeStringParams();
    paramsEnd();
    InputStream in = conn.getInputStream();
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    int b;
    while ((b = in.read()) != -1) {
        out.write(b);
    }
    //out.flush();
    conn.disconnect();
    //in.close();
    //out.close();
    return out.toByteArray();
}

//文件上传的connection的一些必须设置
private void initConnection() throws Exception {
    conn = (HttpURLConnection) this.url.openConnection();
    conn.setDoOutput(true);
    conn.setUseCaches(false);
    conn.setConnectTimeout(10000);//连接超时为10秒  
    conn.setRequestMethod("POST");
    conn.setRequestProperty("Content-Type",
            "multipart/form-data; boundary=" + boundary);
}

//普通字符串数据
private void writeStringParams() throws Exception {
    Set<String> keySet = textParams.keySet();
    for (Iterator<String> it = keySet.iterator(); it.hasNext();) {
        String name = it.next();
        String value = textParams.get(name);
        ds.writeBytes("--" + boundary + "\r\n");
        ds.writeBytes("Content-Disposition: form-data; name=\"" + name
                + "\"\r\n");
        ds.writeBytes("\r\n");
        ds.writeBytes(encode(value) + "\r\n");
    }
}

//文件数据
private void writeFileParams() throws Exception {
    Set<String> keySet = fileparams.keySet();
    for (Iterator<String> it = keySet.iterator(); it.hasNext();) {
        String name = it.next();
        File value = fileparams.get(name);
        ds.writeBytes("--" + boundary + "\r\n");
        ds.writeBytes("Content-Disposition: form-data; name=\"" + name
                + "\"; filename=\"" + encode(value.getName()) + "\"\r\n");
        ds.writeBytes("Content-Type: " + getContentType(value) + "\r\n");
        ds.writeBytes("\r\n");
        ds.write(getBytes(value));
        ds.writeBytes("\r\n");
    }
}

//获取文件的上传类型，图片格式为image/png,image/jpg等。非图片为application/octet-stream
private String getContentType(File f) throws Exception {

    //return "application/octet-stream";  // 此行不再细分是否为图片，全部作为application/octet-stream 类型
    ImageInputStream imagein = ImageIO.createImageInputStream(f);
    if (imagein == null) {
        return "application/octet-stream";
    }
    Iterator<ImageReader> it = ImageIO.getImageReaders(imagein);
    if (!it.hasNext()) {
        imagein.close();
        return "application/octet-stream";
    }
    imagein.close();
    return "image/" + it.next().getFormatName().toLowerCase();//将FormatName返回的值转换成小写，默认为大写

}

//把文件转换成字节数组
private byte[] getBytes(File f) throws Exception {
    FileInputStream in = new FileInputStream(f);
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    byte[] b = new byte[1024];
    int n;
    while ((n = in.read(b)) != -1) {
        out.write(b, 0, n);
    }
    in.close();
    return out.toByteArray();
}

//添加结尾数据
private void paramsEnd() throws Exception {
    ds.writeBytes("--" + boundary + "--" + "\r\n");
    ds.writeBytes("\r\n");
}

// 对包含中文的字符串进行转码，此为UTF-8。服务器那边要进行一次解码
private String encode(String value) throws Exception {
    return URLEncoder.encode(value, "UTF-8");
}

public static void main(String[] args) throws Exception {//
    HttpPostUtil u = new HttpPostUtil("地址");//
    u.addTextParameter("fileType", "1");
    u.addFileParameter("file", new File("C:\\Users\\Administrator\\Pictures\\hq1.jpg"));
    //u.addTextParameter("text", "中文");
    byte[] b = u.send();
    String result = new String(b, "utf-8");
    System.out.println(result);
}

}