HttpURLConnection 发送https请求 并且配置连接池

要使用 `HttpURLConnection` 发送 `https` 请求并配置连接池，可以按照以下步骤操作：

1. 获取 `SSLContext` 对象，用于创建 `SSLSocketFactory` 对象，以便在 `HttpsURLConnection` 中使用：

SSLContext sslContext = SSLContext.getInstance("TLS");
sslContext.init(null, null, null);
SSLSocketFactory sslSocketFactory = sslContext.getSocketFactory();

2. 创建连接池对象 `PoolingHttpClientConnectionManager`，并设置最大连接数和每个路由的最大连接数：

PoolingHttpClientConnectionManager connManager = new PoolingHttpClientConnectionManager();
connManager.setMaxTotal(200);
connManager.setDefaultMaxPerRoute(20);

3. 创建 `HttpClient` 对象，设置连接池和请求参数：

HttpClient httpClient = HttpClients.custom()
        .setSSLSocketFactory(sslSocketFactory)
        .setConnectionManager(connManager)
        .build();

4. 创建 `URL` 对象，并打开连接：

URL url = new URL("https://example.com");
HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();

5. 设置连接的一些属性，如请求方法、超时时间、是否允许重定向等：

connection.setRequestMethod("GET");
connection.setConnectTimeout(5000);
connection.setReadTimeout(5000);
connection.setInstanceFollowRedirects(false);

6. 设置请求头部信息：

connection.setRequestProperty("User-Agent", "Mozilla/5.0");
connection.setRequestProperty("Accept-Language", "en-US,en;q=0.5");

7. 发送请求并读取响应：

InputStream inputStream = connection.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
String line;
StringBuilder response = new StringBuilder();
while ((line = reader.readLine()) != null) {
    response.append(line);
}
reader.close();

完整代码示例：

import org.apache.http.client.HttpClient;
import org.apache.http.conn.ssl.NoopHostnameVerifier;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;

import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSocketFactory;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;

public class HttpsExample {

    public static void main(String[] args) throws Exception {
        SSLContext sslContext = SSLContext.getInstance("TLS");
        sslContext.init(null, null, null);
        SSLSocketFactory sslSocketFactory = sslContext.getSocketFactory();

        PoolingHttpClientConnectionManager connManager = new PoolingHttpClientConnectionManager();
        connManager.setMaxTotal(200);
        connManager.setDefaultMaxPerRoute(20);

        HttpClient httpClient = HttpClients.custom()
                .setSSLSocketFactory(sslSocketFactory)
                .setConnectionManager(connManager)
                .build();

        URL url = new URL("https://example.com");
        HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();

        connection.setRequestMethod("GET");
        connection.setConnectTimeout(5000);
        connection.setReadTimeout(5000);
        connection.setInstanceFollowRedirects(false);

        connection.setRequestProperty("User-Agent", "Mozilla/5.0");
        connection.setRequestProperty("Accept-Language", "en-US,en;q=0.5");

        InputStream inputStream = connection.getInputStream();
        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
        String line;
        StringBuilder response = new StringBuilder();
        while ((line = reader.readLine()) != null) {
            response.append(line);
        }
        reader.close();

        System.out.println(response.toString());
    }
}