org.apache.commons.httpclient工具類

import org.apache.commons.httpclient.DefaultHttpMethodRetryHandler;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpMethod;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.NameValuePair;
import org.apache.commons.httpclient.URIException;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.methods.StringRequestEntity;
import org.apache.commons.httpclient.params.HttpConnectionManagerParams;
import org.apache.commons.httpclient.params.HttpMethodParams;
import org.apache.commons.httpclient.util.URIUtil;
import org.apache.commons.lang3.StringUtils;
import org.apache.http.HttpEntity;
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.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.StreamUtils;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

public class HttpUtils {

    private static final Logger logger = LoggerFactory.getLogger(HttpUtil.class);

    /**
     * 執行一個HTTP GET請求，返回請求響應的HTML
     *
     * @param url 請求的URL地址
     * @return 返回請求響應的HTML
     */
    public static int doGet(String url) {
        HttpClient client = new HttpClient();
        HttpMethod method = new GetMethod(url);

        try {
            client.executeMethod(method);
        } catch (URIException e) {
            logger.error("執行HTTP Get請求時，發生異常！", e);
            return HttpStatus.SC_BAD_REQUEST;
        } catch (IOException e) {
            logger.error("執行HTTP Get請求" + url + "時，發生異常！", e);
            return HttpStatus.SC_BAD_REQUEST;
        } finally {
            method.releaseConnection();
        }
        logger.info("執行HTTP GET請求，返回碼: {}", method.getStatusCode());
        return method.getStatusCode();
    }

    /**
     * 執行一個帶參數的HTTP GET請求，返回請求響應的JSON字符串
     *
     * @param url 請求的URL地址
     * @return 返回請求響應的JSON字符串
     */
    public static String doGet(String url, String param) {
        // 構造HttpClient的實例
        HttpClient client = new HttpClient();
        //設置參數
        // 建立GET方法的實例
        GetMethod method = new GetMethod(url + "?" + param);
        // 使用系統提供的默認的恢復策略
        method.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,
                new DefaultHttpMethodRetryHandler());
        try {
            // 執行getMethod
            client.executeMethod(method);
            if (method.getStatusCode() == HttpStatus.SC_OK) {
                return StreamUtils.copyToString(method.getResponseBodyAsStream(), Charset.forName("utf-8"));
            }
        } catch (IOException e) {
            logger.error("執行HTTP Get請求" + url + "時，發生異常！", e);
        } finally {
            method.releaseConnection();
        }
        return null;
    }

    /**
     * 執行一個HTTP GET請求，返回請求響應的HTML
     *
     * @param url         請求的URL地址
     * @param queryString 請求的查詢參數,能夠爲null
     * @param charset     字符集
     * @param pretty      是否美化
     * @return 返回請求響應的HTML
     */
    public static String doGet(String url, String queryString, String charset, boolean pretty) {
        //logger.info("http的請求地址爲:"+url);
        logger.info("http的請求參數爲：" + queryString);

        StringBuffer response = new StringBuffer();
        HttpClient client = new HttpClient();
        HttpMethod method = new GetMethod(url);

        try {
            if (StringUtils.isNotBlank(queryString)) {
                method.setQueryString(URIUtil.encodeQuery(queryString));
            }

            HttpConnectionManagerParams managerParams = client.getHttpConnectionManager().getParams();

            // 設置鏈接的超時時間 
            managerParams.setConnectionTimeout(3 * 60 * 1000);

            // 設置讀取數據的超時時間 
            managerParams.setSoTimeout(5 * 60 * 1000);

            client.executeMethod(method);
            logger.info("http的請求地址爲:" + url + ",返回的狀態碼爲" + method.getStatusCode());

            BufferedReader reader = new BufferedReader(new InputStreamReader(method.getResponseBodyAsStream(), charset));
            String line;
            while ((line = reader.readLine()) != null) {
                if (pretty) {
                    response.append(line).append(System.getProperty("line.separator"));
                } else {
                    response.append(line);
                }
            }

            reader.close();

        } catch (Exception e) {
            logger.error("執行HTTP Get請求" + url + "時，發生異常！" + e);
            return response.toString();
        } finally {
            method.releaseConnection();
        }
        return response.toString();

    }

    /**
     * 執行一個帶參數的HTTP POST請求，返回請求響應的JSON字符串
     *
     * @param url 請求的URL地址
     * @param map 請求的map參數
     * @return 返回請求響應的JSON字符串
     */
    public static String doPost(String url, Map<String, Object> map) {
        // 構造HttpClient的實例
        HttpClient httpClient = new HttpClient();
        // 建立POST方法的實例
        PostMethod method = new PostMethod(url);

        // 這個basicNameValue**放在List中
        List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
        // 建立basicNameValue***對象參數
        if (map != null) {
            for (Map.Entry<String, Object> entry : map.entrySet()) {
                nameValuePairs.add(new NameValuePair(entry.getKey(), entry.getValue().toString()));
            }
        }

        // 填入各個表單域的值
        NameValuePair[] param = nameValuePairs.toArray(new NameValuePair[nameValuePairs.size()]);

        method.setRequestHeader("Content-Type", "application/x-www-form-urlencoded;charset=utf-8");

        // 將表單的值放入postMethod中
        method.addParameters(param);
        try {
            // 執行postMethod
            int statusCode = httpClient.executeMethod(method);
            if (method.getStatusCode() == HttpStatus.SC_OK) {
                return StreamUtils.copyToString(method.getResponseBodyAsStream(), Charset.forName("utf-8"));
            }
        } catch (UnsupportedEncodingException e1) {
            logger.error(e1.getMessage());
        } catch (IOException e) {
            logger.error("執行HTTP Post請求" + url + "時，發生異常！" + e.toString());
        } finally {
            method.releaseConnection();
        }
        return null;
    }

    /**
     * 執行一個HTTP POST請求，返回請求響應的HTML
     *
     * @param url     請求的URL地址
     * @param reqStr  請求的查詢參數,能夠爲null
     * @param charset 字符集
     * @return 返回請求響應的HTML
     */
    public static String doPost(String url, String reqStr, String contentType, String charset) {
        HttpClient client = new HttpClient();

        PostMethod method = new PostMethod(url);
        try {
            HttpConnectionManagerParams managerParams = client
                    .getHttpConnectionManager().getParams();
            managerParams.setConnectionTimeout(30000); // 設置鏈接超時時間(單位毫秒)
            managerParams.setSoTimeout(30000); // 設置讀數據超時時間(單位毫秒)

            method.setRequestEntity(new StringRequestEntity(reqStr, contentType, "utf-8"));

            client.executeMethod(method);
            logger.info("返回的狀態碼爲" + method.getStatusCode());
            if (method.getStatusCode() == HttpStatus.SC_OK) {
                return StreamUtils.copyToString(method.getResponseBodyAsStream(), Charset.forName(charset));
            }
        } catch (UnsupportedEncodingException e1) {
            logger.error(e1.getMessage());
            return "";
        } catch (IOException e) {
            logger.error("執行HTTP Post請求" + url + "時，發生異常！" + e.toString());

            return "";
        } finally {
            method.releaseConnection();
        }

        return null;
    }

    /**
     * @param url
     * @param entity
     * @return
     * @throws IOException
     */
    public static String doPost(String url, HttpEntity entity) {

        //建立httpclient對象
        CloseableHttpClient client = HttpClients.createSystem();
        //建立post方式請求對象
        HttpPost httpPost = new HttpPost(url);
        //設置參數到請求對象中
        httpPost.setEntity(entity);

        BufferedReader reader = null;
        try {
            CloseableHttpResponse response = client.execute(httpPost);
            logger.info("Status:" + response.getStatusLine().getStatusCode());

            if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
                String inputLine;
                StringBuffer buffer = new StringBuffer();
                while ((inputLine = reader.readLine()) != null) {
                    buffer.append(inputLine);
                }
                reader.close();
                return buffer.toString();
            }
        } catch (IOException ex) {
            logger.info("執行http post請求出錯,exception={}", ex.getMessage());
        } finally {
            try {
                client.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }
}

注：

若是PostMethod提交的是中文字符，須要加上相應的編碼格式： post.setRequestHeader("Content-Type","application/x-www-form-urlencoded;charset=utf-8"); 
若是GetMethod提交的參數有中文字符，須要先轉換成utf-8格式：String param = "enterpriseName="+ URLEncoder.encode("中國移動", "utf-8"); HttpUtil.doGet(param, url);

maven依賴說明
commons-httpclient 是 apache-commons 項目下的一個子項目，後來被 HttpComponents 取代，後者提供了更好的性能和更大的靈活性。

commons-httpclient的GAV地址爲
<dependency>
<groupId>commons-httpclient</groupId>
<artifactId>commons-httpclient</artifactId>
<version>3.1</version>
</dependency>
其最新版本爲3.1，且已經再也不更新；


HttpComponents的GAV地址爲
<!-- https://mvnrepository.com/artifact/org.apache.httpcomponents/httpclient -->
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.5</version>
</dependency>