【Java】不依赖第三方库发送post请求

版权声明：原创 https://blog.csdn.net/hangvane123/article/details/82933604

源码取自某短信平台，不依赖第三方库，无异常处理代码，仅供参考

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.URL;
import java.net.URLConnection;

public class HttpRequest {
    /**
     * 向指定 URL 发送POST方法的请求
     * 
     * @param url
     *            发送请求的 URL
     * @return 所代表远程资源的响应结果
     */
    public static String sendPost(String url, String param) {
        PrintWriter out = null;
        BufferedReader in = null;
        String result = "";
        try {
            URL realUrl = new URL(url);
            // 打开和URL之间的连接
            URLConnection conn = realUrl.openConnection();
            // 设置通用的请求属性
            conn.setRequestProperty("accept", "*/*");
            conn.setRequestProperty("connection", "Keep-Alive");
            conn.setRequestProperty("user-agent",
                    "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            // 发送POST请求必须设置如下两行
            conn.setDoOutput(true);
            conn.setDoInput(true);
            // 获取URLConnection对象对应的输出流
            out = new PrintWriter(conn.getOutputStream());
            // 发送请求参数
            out.print(param);
            // flush输出流的缓冲
            out.flush();
            // 定义BufferedReader输入流来读取URL的响应
            in = new BufferedReader(
                    new InputStreamReader(conn.getInputStream()));
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }
        } catch (Exception e) {
            System.out.println("发送 POST 请求出现异常！"+e);
            e.printStackTrace();
        }
        //使用finally块来关闭输出流、输入流
        finally{
            try{
                if(out!=null){
                    out.close();
                }
                if(in!=null){
                    in.close();
                }
            }
            catch(IOException ex){
                ex.printStackTrace();
            }
        }
        return result;
    }    
}

测试一下：

System.out.println(HttpRequest.sendPost("http://httpbin.org/post", "abc"));

返回值：

{
    "args": { }, 
    "data": "", 
    "files": { }, 
    "form": {
        "abc": ""
    }, 
    "headers": {
        "Accept": "*/*", 
        "Connection": "close", 
        "Content-Length": "3", 
        "Content-Type": "application/x-www-form-urlencoded", 
        "Host": "httpbin.org", 
        "User-Agent": "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)"
    }, 
    "json": null, 
    "origin": "111.11.1.111", 
    "url": "http://httpbin.org/post"
}

测试成功！