HttpClient基本功能的使用 Get方式

一、GET 方法
    使用 HttpClient 需要以下 6 个步骤：
    1. 创建 HttpClient 的实例
    2. 创建某种连接方法的实例，在这里是 GetMethod。在 GetMethod 的构造函数中传入待连接的地址
    3. 调用第一步中创建好的实例的 execute 方法来执行第二步中创建好的 method 实例
    4. 读 response
    5. 释放连接。无论执行方法是否成功，都必须释放连接
    6. 对得到后的内容进行处理
根据以上步骤，我们来编写用GET方法取得某网页内容的代码。

1、大部分情况下 HttpClient 默认的构造函数已经足够使用。

HttpClient httpClient  =   new  HttpClient();

2、创建GET方法的实例。
      在GET方法的构造函数中传入待连接的地址即可。用GetMethod将会自动处理转发过程，如果想要把自动处理转发过程去掉的话，可以调用方法setFollowRedirects(false)。

GetMethod getMethod  =   new  GetMethod( " http://www.ibm.com/ " );

3、调用 httpClient 的 executeMethod 方法来执行 getMethod。

   由于是执行在网络上的程序，在运行executeMethod方法的时候，需要处理两个异常，分别是HttpException和 IOException。

HttpException：引起第一种异常的原因主要可能是在构造getMethod的时候传入的协议不对，比如将"http"写成了"htp"，或者服务 器端返回的内容不正常等，并且该异常发生是不可恢复的；

     IOException：一般是由于网络原因引起的异常，对于这种异常 （IOException），HttpClient会根据你指定的恢复策略自动试着重新执行executeMethod方法。HttpClient的恢复 策略可以自定义（通过实现接口HttpMethodRetryHandler来实现）。通过httpClient的方法setParameter设置你实 现的恢复策略。

本例中使用的是系统提供的默认恢复策略，该策略在碰到第二类异常的时候将自动重试3次。executeMethod返回值是一个整数，表示 了执行该方法后服务器返回的状态码，该状态码能表示出该方法执行是否成功、需要认证或 者页面发生了跳转（默认状态下GetMethod的实例是自动处理跳 转的）等。

getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,new  DefaultHttpMethodRetryHandler()); // 设置成了默认的恢复策略，在发生异常时候将自动重试3次，在这里你也可以设置成自定义的恢复策略 
int  statusCode  =  client.executeMethod(getMethod); // 执行getMethod
if  (statusCode  !=  HttpStatus.SC_OK) {
       System.err.println( " Method failed:  "   +  getMethod.getStatusLine());
 }

4、在返回的状态码正确后，即可取得内容。

取得目标地址的内容有三种方法：
      Ⅰ、getResponseBody，该方法返回的是目标的二进制的byte流；
      Ⅱ、getResponseBodyAsString，这个方法返回的是String类型，值得注意的是该方法返回的String的编码是根据系统默认的编码方式，所以返回的String值可能编码类型有误；
      Ⅲ、getResponseBodyAsStream，这个方法对于目标地址中有大量数据需要传输是最佳的。
      在这里我们使用了最简单的 getResponseBody方法。

byte [] responseBody  =  method.getResponseBody();

5、释放连接。
       无论执行方法是否成功，都必须释放连接。

method.releaseConnection();

6、处理内容。
      在这一步中根据你的需要处理内容，本例中只是简单的将内容打印到控制台。System.out.println( new  String(responseBody));

package com.asiainfo.hsop.common.utils;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import com.alibaba.fastjson.JSONObject;
import org.apache.commons.httpclient.DefaultHttpMethodRetryHandler;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.MultiThreadedHttpConnectionManager;
import org.apache.commons.httpclient.NameValuePair;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.params.HttpClientParams;
import org.apache.commons.httpclient.params.HttpMethodParams;
import org.apache.commons.httpclient.protocol.Protocol;
import org.apache.commons.lang3.StringUtils;
import org.apache.http.HttpEntity;
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.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.entity.mime.HttpMultipartMode;
import org.apache.http.entity.mime.MultipartEntityBuilder;
import org.apache.http.entity.mime.content.FileBody;
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 org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

/**
 * 处理http和https协议请求,根据请求url判断协议类型
 *
 * @author yangxiaobing
 * @date 2017/9/6
 */
public class HttpUtil {

    private static Logger logger = LogManager.getLogger(HttpUtil.class);
    private static final int HTTP_DEFAULT_TIMEOUT = 15000;               //超时时间默认为15秒
    private static final int HTTP_SOCKET_TIMEOUT = 30000;               //连接状态下没有收到数据的话强制断时间为30秒
    private static final int MAX_TOTAL_CONNECTIONS = 500;                 //最大连接数
    private static final int CONN_MANAGER_TIMEOUT = 500;                  //该值就是连接不够用的时候等待超时时间，一定要设置，而且不能太大

    private static MultiThreadedHttpConnectionManager httpConnectionManager = new MultiThreadedHttpConnectionManager();

    //接口调用频繁，结果出现了很多ConnectTimeoutException 配置优化，共用HttpClient，减少开销
    static {
        //每主机最大连接数和总共最大连接数，通过hosfConfiguration设置host来区分每个主机
        //client.getHttpConnectionManager().getParams().setDefaultMaxConnectionsPerHost(8);
        httpConnectionManager.getParams().setMaxTotalConnections(MAX_TOTAL_CONNECTIONS);
        httpConnectionManager.getParams().setConnectionTimeout(HTTP_DEFAULT_TIMEOUT);//连接超时时间
        httpConnectionManager.getParams().setSoTimeout(HTTP_SOCKET_TIMEOUT);         //连接状态下没有收到数据的话强制断时间
        httpConnectionManager.getParams().setLongParameter(HttpClientParams.CONNECTION_MANAGER_TIMEOUT, CONN_MANAGER_TIMEOUT);
        //是否计算节省带宽
        httpConnectionManager.getParams().setTcpNoDelay(true);
        //延迟关闭时间
        httpConnectionManager.getParams().setLinger(0);
        //失败的情况下会默认进行3次尝试,成功之后不会再尝试    ------关闭
        httpConnectionManager.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler(0, false));
    }

    /**
     * 构建 httpsclient 请求
     *
     * @return
     */
    private static HttpClient getHttpClient() {
        HttpClient httpClient = new HttpClient(httpConnectionManager);
        httpClient.getParams().setParameter(HttpMethodParams.HTTP_CONTENT_CHARSET, "UTF-8");
        return httpClient;
    }

    /**
     * POST请求统一入口
     */
    public static String post(String url, Map<String, Object> paramMap) {
        logger.info("===>>>调用[post]接口开始...===>>> URL:" + url);
        Long beginTime = System.currentTimeMillis();
        if (StringUtils.isEmpty(url)) {
            return null;
        }
        String result = null;
        if (startsWithIgnoreCase(url, "https")) {
            result = httpsPost(url, paramMap, "UTF-8");
        } else if (startsWithIgnoreCase(url, "http")) {
            result = httpPost(url, paramMap, "UTF-8");
        } else {
            logger.warn("http url format error!");
        }
        logger.info("===>>>调用[post]接口结束   ===>>>URL:" + url + ",耗时:" + (System.currentTimeMillis() - beginTime) + "毫秒");
        return result;
    }

    /**
     * GET请求统一入口
     */
    public static String get(String url) {
        logger.info("===>>>调用[get]接口开始...===>>> URL:" + url);
        Long beginTime = System.currentTimeMillis();
        if (StringUtils.isEmpty(url)) {
            return null;
        }
        String result = null;
        if (startsWithIgnoreCase(url, "https")) {
            result = httpsGet(url, "UTF-8");
        } else if (startsWithIgnoreCase(url, "http")) {
            result = httpGet(url, "UTF-8");
        } else {
            logger.warn("http url format error!");
        }
        logger.info("===>>>调用[get]接口结束   ===>>>URL:" + url + ",耗时:" + (System.currentTimeMillis() - beginTime) + "毫秒");
        return result;
    }

    public static String httpPost(String url, Map<String, Object> paramMap, String encoding) {
        String content = null;
        if (paramMap == null) {
            paramMap = new HashMap<String, Object>();
        }
        logger.info("http param:" + paramMap.toString());
        HttpClient httpClient = getHttpClient();
        PostMethod method = new PostMethod(url);

        if (!paramMap.isEmpty()) {
            for (Map.Entry<String, ?> entry : paramMap.entrySet()) {
                method.addParameter(new NameValuePair(entry.getKey(), entry.getValue().toString()));
            }
        }
        try {
            httpClient.executeMethod(method);
            logger.info("http status : " + method.getStatusLine().getStatusCode());
            content = new String(method.getResponseBody(), encoding);
            logger.info("http response : [" + content + "]");
        } catch (Exception e) {
            logger.error("发起http请求失败[" + url + "]" + ",param" + paramMap.toString(), e);
        } finally {
            method.releaseConnection();
            httpClient.getHttpConnectionManager().closeIdleConnections(0);
        }
        return content;
    }

    public static String httpPost(String url, JSONObject param) {
        String content = null;
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpPost httpPost = new HttpPost(url);

        httpPost.setHeader("Content-Type", "application/json;charset=UTF-8");
        StringEntity se = null;
        try {
            se = new StringEntity(JSONObject.toJSONString(param));
            se.setContentType("text/json");
            httpPost.setEntity(se);

            CloseableHttpResponse response = null;
            response = httpClient.execute(httpPost);
            HttpEntity httpEntity = response.getEntity();
            content = EntityUtils.toString(httpEntity, "UTF-8");
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (httpClient != null) {
                try {
                    httpClient.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return content;
    }

    private static String httpsPost(String url, Map<String, Object> paramMap, String encoding) {
        String content = null;
        HttpClient httpsClient = getHttpClient();
        Protocol myhttps = new Protocol("https", new MySSLProtocolSocketFactory(), 443);
        Protocol.registerProtocol("https", myhttps);
        PostMethod method = new PostMethod(url);
        if (paramMap != null && !paramMap.isEmpty()) {
            for (Map.Entry<String, Object> entry : paramMap.entrySet()) {
                if (null != entry.getValue()) {
                    method.addParameter(new NameValuePair(entry.getKey(), entry.getValue().toString()));
                }
            }
            logger.info("https param : " + paramMap.toString());
        }
        try {
            httpsClient.executeMethod(method);
            logger.info("https status :" + method.getStatusLine().getStatusCode());
            if (method.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                content = new String(method.getResponseBody(), encoding);
                logger.info("https response : [" + content + "]");
            }
        } catch (Exception e) {
            logger.error("https request failed. url : [" + url + "]" + ", param : [" + paramMap + "]", e);
        } finally {
            method.releaseConnection();
            httpsClient.getHttpConnectionManager().closeIdleConnections(0);
        }
        return content;
    }

    private static String httpGet(String url, String encoding) {
        HttpClient httpClient = getHttpClient();
        GetMethod method = new GetMethod(url);
        String result = null;
        try {
            httpClient.executeMethod(method);
            int status = method.getStatusCode();
            if (status == HttpStatus.SC_OK) {
                result = method.getResponseBodyAsString();
            } else {
                logger.error("Method failed: " + method.getStatusLine());
            }
        } catch (HttpException e) {
            // 发生致命的异常，可能是协议不对或者返回的内容有问题
            logger.error("Please check your provided http address!");
            logger.error(e, e);
        } catch (IOException e) {
            // 发生网络异常
            logger.error("发生网络异常！");
            logger.error(e, e);
        } finally {
            // 释放连接
            method.releaseConnection();
            httpClient.getHttpConnectionManager().closeIdleConnections(0);
        }
        return result;
    }

    private static String httpsGet(String url, String encoding) {
        HttpClient httpsClient = getHttpClient();//HttpConnectionManager.alwaysClose=true
        Protocol myhttps = new Protocol("https", new MySSLProtocolSocketFactory(), 443);
        Protocol.registerProtocol("https", myhttps);
        GetMethod method = new GetMethod(url);
        String content = null;
        try {
            httpsClient.executeMethod(method);
            logger.info("https status : " + method.getStatusLine().getStatusCode());
            if (method.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                content = new String(method.getResponseBody(), encoding);
                logger.info("https response : [" + content + "]");
            }
        } catch (Exception e) {
            logger.error("https request failed. url : [" + url + "]", e.getCause());
        } finally {
            method.releaseConnection();
            httpsClient.getHttpConnectionManager().closeIdleConnections(0);
        }
        return content;
    }

    private static boolean startsWithIgnoreCase(String origin, String prefix) {
        int len = prefix.length();
        if (len == 0 || origin.length() < len) {
            return false;
        }
        while (len-- > 0) {
            char a = origin.charAt(len);
            char b = prefix.charAt(len);
            if (a == b || Character.toUpperCase(a) == Character.toUpperCase(b)) {
                continue;
            }
            return false;
        }
        return true;
    }

    public static void main(String args[]) {

      //  String url = "http://10.253.6.202:30001/dipic/api/auditControl/queryTraffic";
        String url = "http://localhost:8180/comm/api/upload.do";
        JSONObject Json = new JSONObject();
        File file = new File("E:\\initParam.properties");
        Map<String,String> map = new HashMap<>();
        map.put("fileName","redis-64bit.rar");
        System.out.println(HttpUtil.postFile(url, file));
       }

        //文件上传，调用fastDFS方法封装层
        public static String postFile(String url, File file){
            CloseableHttpClient httpclient = HttpClients.createDefault();
            CloseableHttpResponse response = null;
            String result = null;
            try {
                RequestConfig requestConfig = RequestConfig.custom().setSocketTimeout(3000)
                        .setConnectTimeout(3000).setConnectionRequestTimeout(3000).build();
//                if (params != null && !params.isEmpty()) {
//                    List<BasicNameValuePair> pairs = new ArrayList<BasicNameValuePair>(params.size());
//                    for (Map.Entry<String, String> entry : params.entrySet()) {
//                        String value = entry.getValue();
//                        if (value != null) {
//                            pairs.add(new BasicNameValuePair(entry.getKey(), value));
//                        }
//                    }
//                    url += "?" + EntityUtils.toString(new UrlEncodedFormEntity(pairs, charset));
//                }
                HttpPost httpPost = new HttpPost(url);
                httpPost.setConfig(requestConfig);
                // 将java.io.File对象添加到HttpEntity（org.apache.http.HttpEntity）对象中
                MultipartEntityBuilder builder = MultipartEntityBuilder.create();
                // 解决上传文件，文件名中文乱码问题
                builder.setCharset(Charset.forName("utf-8"));
                builder.setMode(HttpMultipartMode.BROWSER_COMPATIBLE);// 设置浏览器兼容模式
                builder.addPart("file", new FileBody(file));

                httpPost.setEntity(builder.build());
                response = httpclient.execute(httpPost);

                int statusCode = response.getStatusLine().getStatusCode();
                if (statusCode == HttpStatus.SC_OK) {
                    HttpEntity resEntity = response.getEntity();
                    result = EntityUtils.toString(resEntity);

                    // 消耗掉response
                    EntityUtils.consume(resEntity);
                }
            } catch (Exception e) {
                e.printStackTrace();
            }finally {
                if(response!=null){
                    try {
                        response.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                if(httpclient!=null){
                    try {
                        httpclient.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }

            }
            return result;
        }

    }

HttpUtil工具类

package  test;
  import  java.io.IOException;
   import  org.apache.commons.httpclient. * ;
  import  org.apache.commons.httpclient.methods.GetMethod;
   import  org.apache.commons.httpclient.params.HttpMethodParams;
  public   class  GetSample{
     public   static   void  main(String[] args) {
         // 构造HttpClient的实例
         HttpClient httpClient  =   new  HttpClient();
         // 创建GET方法的实例
          GetMethod getMethod  =   new  GetMethod( " http://www.ibm.com " );
         // 使用系统提供的默认的恢复策略
          getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,
                                                 new  DefaultHttpMethodRetryHandler());
          try  {
            // 执行getMethod
            int  statusCode  =  httpClient.executeMethod(getMethod);
            if  (statusCode  !=  HttpStatus.SC_OK) {
               System.err.println( " Method failed:  "
                                        +  getMethod.getStatusLine());
            }
            // 读取内容
             byte [] responseBody  =  getMethod.getResponseBody();
            // 处理内容
             System.out.println( new  String(responseBody));
         }  catch  (HttpException e) {
            // 发生致命的异常，可能是协议不对或者返回的内容有问题
            System.out.println( " Please check your provided http address! " );
            e.printStackTrace();
         }  catch  (IOException e) {
             // 发生网络异常
             e.printStackTrace();
         }  finally  {
            // 释放连接
            getMethod.releaseConnection();
        }
       }
    }