Java发送get,post请求

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import org.apache.http.HttpEntity;
import org.apache.http.NameValuePair;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

public class HttpRequestUtils {
	/** 
	 * 发送post请求
	 * @param url  请求路径
	 * @param headers 请求参数(需封装成Map<String, String>, 无参数为null)
	 * @return
	 */
	public static String executePost(String url, Map<String, String> headers) {
		String body = "";
		// 创建httpclient对象
		CloseableHttpClient closeableHttpClient = HttpClients.createDefault();
		// 创建post方式请求对象
		HttpPost httpPost = new HttpPost(url);
		// 超时设置
		RequestConfig requestConfig = RequestConfig.custom().setSocketTimeout(2000).setConnectTimeout(2000).build();
		httpPost.setConfig(requestConfig);
		// 装填参数
		List<NameValuePair> nvps = new ArrayList<NameValuePair>();
		if (headers != null) {
			for (Entry<String, String> entry : headers.entrySet()) {
				nvps.add(new BasicNameValuePair(entry.getKey(), entry.getValue()));
			}
		}

		CloseableHttpResponse httpResponse = null;
		try {
			// 设置参数到请求对象中
			httpPost.setEntity(new UrlEncodedFormEntity(nvps, "utf-8"));

			// 设置header信息
			// 指定报文头
			httpPost.setHeader("x-access-token", "52D9C7AE-626F-405C-AB4C-8762E7C32184");

			// 执行请求操作，并拿到结果（同步阻塞）
			httpResponse = closeableHttpClient.execute(httpPost);
			// 获取结果实体
			HttpEntity entity = httpResponse.getEntity();
			if (entity != null) {
				// 按指定编码转换结果实体为String类型
				body = EntityUtils.toString(entity, "utf-8");
			}
			EntityUtils.consume(entity);
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				httpResponse.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		try {
			closeableHttpClient.close(); // 关闭连接、释放资源
		} catch (IOException e) {
			e.printStackTrace();
		}
		return body;
	}

	/**
	 * 发送get请求
	 * @param url  请求路径
	 * @param param 请求参数
	 * @return
	 */
	public static String sendGet(String url, String param) {
		String urlName = url + "?" + param;
		return sendGet(urlName);
	}

	/**
	 * 发送get请求
	 * @param url 请求路径
	 * @return
	 */
	public static String sendGet(String url) {
        String result = "";
        BufferedReader in = null;
        try {
            URL realUrl = new URL(url);
            // 打开和URL之间的连接
            URLConnection connection = realUrl.openConnection();
            // 设置通用的请求属性
            connection.setRequestProperty("accept", "*/*");
            connection.setRequestProperty("connection", "Keep-Alive");
            connection.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            // 建立实际的连接
            connection.connect();
            // 获取所有响应头字段
            Map<String, List<String>> map = connection.getHeaderFields();
            // 遍历所有的响应头字段
            for (String key : map.keySet()) {
                System.out.println(key + "--->" + map.get(key));
            }
            // 定义 BufferedReader输入流来读取URL的响应
            in = new BufferedReader(new InputStreamReader(
                    connection.getInputStream()));
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }
        } catch (Exception e) {
            System.out.println("发送GET请求出现异常！" + e);
            e.printStackTrace();
        }
        // 使用finally块来关闭输入流
        finally {
            try {
                if (in != null) {
                    in.close();
                }
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
        return result;
    }
}