Java调用https接口

http 与 https 区别

https协议需要到ca申请证书，一般免费证书较少，因而需要一定费用。
http是超文本传输协议，信息是明文传输，https则是具有安全性的ssl加密传输协议。
http和https使用的是完全不同的连接方式，用的端口也不一样，前者是80，后者是443。
http的连接很简单，是无状态的；HTTPS协议是由SSL+HTTP协议构建的可进行加密传输、身份认证的网络协议，比http协议安全。

上代码：
HttpsTrustClient 类

import javax.net.ssl.X509TrustManager;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;

public class HttpsTrustClient implements X509TrustManager {
    @Override
    public void checkClientTrusted(X509Certificate[] x509Certificates, String s) throws CertificateException {

    }

    @Override
    public void checkServerTrusted(X509Certificate[] x509Certificates, String s) throws CertificateException {

    }

    @Override
    public X509Certificate[] getAcceptedIssuers() {
//        return new X509Certificate[0];
        return null;
    }
}

HttpRequestUtil 实现post请求

import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManager;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.URL;

public class HttpRequestUtil {
    public static String sendPost(String url, String param) {
        PrintWriter out = null;
        BufferedReader in = null;
        String result = "";
        try {
            // 创建SSLContext对象，并使用我们指定的信任管理器初始化
            TrustManager[] tm = { new HttpsTrustClient() };
            SSLContext sslContext = SSLContext.getInstance("SSL");
            sslContext.init(null, tm, new java.security.SecureRandom());

            // 从上述SSLContext对象中得到SSLSocketFactory对象
            SSLSocketFactory ssf = sslContext.getSocketFactory();
            // 打开和URL之间的连接
            URL realUrl = new URL(url);
            HttpsURLConnection conn = (HttpsURLConnection) realUrl.openConnection();
            conn.setSSLSocketFactory(ssf);
            // 设置通用的请求属性
            conn.setRequestProperty("accept", "*/*");
            conn.setRequestProperty("connection", "Keep-Alive");
            conn.setRequestProperty("content-Type", "application/json");
            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) {
            e.printStackTrace();
        } finally {// 使用finally块来关闭输出流、输入流
            try {
                if (out != null) {
                    out.close();
                }
                if (in != null) {
                    in.close();
                }
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        return result;
    }
}

测试

public class Test {
	public static void main(String[] args){ 
        String url = "访问地址";
        Map<String,Object> param = new HashMap<String,Object>();
	    param.put("参数", "值");
	    String message = JSONUtils.toJSONString(param);
        String str = HttpRequest.sendPost(url, message);
        System.out.println(str);
	}
}

参考：https://blog.youkuaiyun.com/qq_17476231/article/details/95359207