apache httpclient 4 范例

以下是使用 Apache HttpClient 4 发送 HTTP GET 请求的示例代码：

import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

import java.io.IOException;

public class HttpGetExample {

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

        CloseableHttpClient httpclient = HttpClients.createDefault();
        HttpGet httpGet = new HttpGet("http://www.example.com");

        try (CloseableHttpResponse response = httpclient.execute(httpGet)) {
            HttpEntity entity = response.getEntity();
            if (entity != null) {
                String result = EntityUtils.toString(entity);
                System.out.println(result);
            }
        }
    }
}

以上代码使用 HttpClients.createDefault() 创建一个默认的 CloseableHttpClient 对象，然后使用 HttpGet 发送一个 GET 请求到指定的 URL。接着，利用 try-with-resources 语句自动关闭 CloseableHttpResponse 对象。在 try-with-resources 代码块中，使用 response.getEntity() 获取响应的实体，并将其转换为字符串。最后，输出响应的字符串结果。