Java常用工具類： HttpClientUtil

package *************************

import org.apache.commons.httpclient.HttpStatus;
import org.apache.http.NameValuePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.entity.StringEntity;
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;

import java.io.IOException;
import java.net.URI;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

/**
 * <p>
 * HttpClient工具類
 * </p>
 *
 * @author Mazen
 * @since 2019-12-31
 */
public class HttpClientUtil {
    private HttpClientUtil() {
    }

    public static String doGet(String url, Map<String, String> param) {

        // 創建Httpclient對象
        CloseableHttpClient httpclient = HttpClients.createDefault();

        String resultString = "";
        CloseableHttpResponse response = null;
        try {
            // 創建uri
            URIBuilder builder = new URIBuilder(url);
            if (param != null) {
                for (String key : param.keySet()) {
                    builder.addParameter(key, param.get(key));
                }
            }
            URI uri = builder.build();

            // 創建http GET請求
            HttpGet httpGet = new HttpGet(uri);

            // 執行請求
            response = httpclient.execute(httpGet);
            // 判斷返回狀態是否爲200
            if (response.getStatusLine().getStatusCode() == 200) {
                resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (response != null) {
                    response.close();
                }
                httpclient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return resultString;
    }

    public static String doGet(String url) {
        return doGet(url, null);
    }

    public static String doPost(String url, Map<String, Object> param) {
        // 創建Httpclient對象
        CloseableHttpClient httpClient = HttpClients.createDefault();
        CloseableHttpResponse response = null;
        String resultString = "";
        try {
            // 創建Http Post請求
            HttpPost httpPost = new HttpPost(url);
            // 創建參數列表
            if (param != null) {
                List<NameValuePair> paramList = new ArrayList<NameValuePair>();
                for (String key : param.keySet()) {
                    paramList.add(new BasicNameValuePair(key, (String) param.get(key)));
                }
                // 模擬表單
                UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList);
                httpPost.setEntity(entity);
            }
            // 執行http請求
            response = httpClient.execute(httpPost);
            resultString = EntityUtils.toString(response.getEntity(), "utf-8");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (response != null) {
                    response.close();
                }
                httpClient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        return resultString;
    }

    public static String doPost(String url) {
        return doPost(url, null);
    }

    public static String doPostJson(String url, String json) throws Exception {
        // 創建Httpclient對象
        CloseableHttpClient httpClient = HttpClients.createDefault();
        CloseableHttpResponse response = null;
        String resultString = "";
        try {
            StringEntity entity = new StringEntity(json, "utf-8");
            entity.setContentEncoding("UTF-8");

            // 創建Http Post請求
            HttpPost httpPost = new HttpPost(url);
            httpPost.setHeader("Content-Type", "application/json");
            httpPost.setEntity(entity);

            // 執行http請求
            response = httpClient.execute(httpPost);

            if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
            }
        } catch (Exception e) {
            throw e;
        } finally {
            try {
                if (response != null) {
                    response.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        return resultString;
    }

}

依賴：

<dependency>
	<groupId>org.apache.httpcomponents</groupId>
	<artifactId>httpcore</artifactId>
	<version>4.4.11</version>
</dependency>
<dependency>
	<groupId>commons-httpclient</groupId>
	<artifactId>commons-httpclient</artifactId>
	<version>3.1</version>
</dependency>
<dependency>
	<groupId>org.apache.httpcomponents</groupId>
	<artifactId>httpclient</artifactId>
	<version>4.5.9</version>
</dependency>