1、開發需求

 需要實現在服務端發起HTTP／HTTPS請求，訪問其他程式資源。

2、URLConnection和HTTPClient的比較

  HttpClient是個很不錯的開源框架，封裝了訪問http的請求頭，引數，內容體，響應等等，
  DefaultHttpClient和它的兄弟AndroidHttpClient都是HttpClient具體的實現類，它們都擁有眾多的API，而且實現比較穩定，bug數量也很少。

3、使用Apache的HttpClient傳送GET和POST請求

1. 使用幫助類HttpClients建立CloseableHttpClient物件.
2. 
 
基於要傳送的HTTP請求型別建立HttpGet或者HttpPost例項.
3. 使用addHeader方法新增請求頭部,諸如User-Agent, Accept-Encoding等引數.
4. 對於POST請求,建立NameValuePair列表,並新增所有的表單引數.然後把它填充進HttpPost實體.
5. 通過執行此HttpGet或者HttpPost請求獲取CloseableHttpResponse例項
6. 從此CloseableHttpResponse例項中獲取狀態碼,錯誤資訊,以及響應頁面等等.
7. 最後關閉HttpClient資源.

4、SSL與TLS的區別以及介紹

SSL
    SSL是Netscape公司所提出的安全保密協議，在瀏覽器（如Internet Explorer、Netscape Navigator）和Web伺服器（如Netscape的Netscape Enterprise Server、ColdFusion Server等等）之間構造安全通道來進行資料傳輸，SSL執行在TCP/IP層之上、應用層之下，為應用程式提供加密資料通道，它採用了RC4、MD5以及RSA等加密演算法，使用40
 
 位的金鑰，適用於商業資訊的加密。
    同時，Netscape公司相應開發了HTTPS協議並內置於其瀏覽器中。
    HTTPS實際上就是HTTP over SSL，它使用預設埠443，而不是像HTTP那樣使用埠80來和TCP/IP進行通訊。
    HTTPS協議使用SSL在傳送方把原始資料進行加密，然後在接受方進行解密，加密和解密需要傳送方和接受方通過交換共知的金鑰來實現，因此，所傳送的資料不容易被網路黑客截獲和解密。 然而，加密和解密過程需要耗費系統大量的開銷，嚴重降低機器的效能，相關測試資料表明使用HTTPS協議傳輸資料的工作效率只有使用HTTP協議傳輸的十分之一。假如為了安全保密，將一個網站所有的Web應用都啟用SSL技術來加密，並使用HTTPS協議進行傳輸，那麼該網站的效能和效率將會大大降低，而且沒有這個必要，因為一般來說並不是所有資料都要求那麼高的安全保密級別。

TLS
   安全傳輸層協議
　　TLS：Transport
 
 Layer Security
　　安全傳輸層協議（TLS）用於在兩個通訊應用程式之間提供保密性和資料完整性。該協議由兩層組成： TLS 記錄協議（TLS Record）和 TLS 握手協議（TLS Handshake）。較低的層為 TLS 記錄協議，位於某個可靠的傳輸協議（例如 TCP）上面。

5、 post請求封裝的工具類

import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.lang.reflect.Method;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.security.KeyManagementException;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;


import com.sun.corba.se.impl.orbutil.threadpool.TimeoutException;
import org.apache.commons.httpclient.util.TimeoutController;
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.conn.ssl.SSLConnectionSocketFactory;
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 org.apache.log4j.Logger;
import cn.qtone.hjy.service.bean.yd.sync.AccountPasswordInfoSyncItem;
import cn.qtone.hjy.service.bean.yd.sync.OrderInfoSyncItem;
import cn.qtone.hjy.service.bean.yd.sync.YdOrderRelationshipInfoSyncItem;
import cn.qtone.hjy.service.core.DES;
import cn.qtone.hjy.service.dao.YdEduDao;
import cn.qtone.util.SpringUtil;
import com.alibaba.fastjson.JSONObject;
import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;


public class HttpClientUtil {

    static Logger log = Logger.getLogger(HttpClientUtil.class) ;

    private static  RequestConfig requestConfig = RequestConfig.custom().setSocketTimeout(10000).setConnectTimeout(10000).build();//設定請求和傳輸超時時間

    private static CloseableHttpClient httpclient = HttpClients.createDefault();

    public static String send(String httpUrl, String message) throws IOException {
        String result = null ;
        HttpPost httpPost = new HttpPost(httpUrl);
        //設定資料讀取超時5s   傳輸超時5s    連結請求超時5s
        RequestConfig requestConfig = RequestConfig.custom()
                    .setSocketTimeout(5000)
                    .setConnectTimeout(5000)
                    .setConnectionRequestTimeout(5000)
                    .build();        
        httpPost.setConfig(requestConfig) ;
        message = URLEncoder.encode(message, "UTF-8") ;
        StringEntity entity = new StringEntity(message);
        httpPost.setEntity(entity);
        CloseableHttpResponse response = httpclient.execute(httpPost);
        BufferedReader in = null ;
        try {
            InputStream content = response.getEntity().getContent() ;
            in = new BufferedReader(new InputStreamReader(content));
            StringBuilder sb = new StringBuilder();
            String line = "" ;
            while ((line = in.readLine()) != null) {
                sb.append(line);
            }
            result = sb.toString() ;
            System.out.println("接收原始報文：" + URLDecoder.decode(result, "UTF-8")) ;
        } finally {
            EntityUtils.consume(response.getEntity());
            response.close();
        }
        return result ;
    }

    public static String post(String httpUrl, String message) throws Exception {
        String result = null ;
        CloseableHttpClient httpclient = HttpClients.createDefault();
        BufferedReader in = null ;
        HttpPost httpPost = new HttpPost(httpUrl);
        httpPost.setConfig(requestConfig);
        List <NameValuePair> nvps = new ArrayList <NameValuePair>();
        nvps.add(new BasicNameValuePair("tokenId", DES.encrypt(message)));
        httpPost.setEntity(new UrlEncodedFormEntity(nvps));
        try {
            System.out.println("傳送報文：" + message);
            System.out.println("傳送報文：" + DES.encrypt(message)) ;
            CloseableHttpResponse response = httpclient.execute(httpPost);
            InputStream content = response.getEntity().getContent() ;
            in = new BufferedReader(new InputStreamReader(content, "UTF-8"));
            StringBuilder sb = new StringBuilder();
            String line = "" ;
            while ((line = in.readLine()) != null) {
                sb.append(line);
            }
            System.out.println("響應報文：" + sb.toString()) ;
            //result = URLDecoder.decode(sb.toString(), "UTF-8") ;
            //result = DES.decrypt(result) ;
            //System.out.println("完成：" + JSONObject.parseObject(result) + "\n");
            return result ;
        } catch (Exception e) {
            e.printStackTrace() ;
        } finally {
            httpclient.close();
        }
        return null ;
    }

    /**
     * 發起post請求，請求引數以Map集合形式傳入，封裝到List <NameValuePair> 發起post請求
     * @param httpUrl
     * @param params
     * @return
     * @throws Exception
     */
    public static String post(String httpUrl, Map<String, String> params) throws Exception {
        String result = null ;
        CloseableHttpClient httpclient = createSSLClientDefault();
        //httpclient.
        //httpclient.
        BufferedReader in = null ;
        HttpPost httpPost = new HttpPost(httpUrl);
        httpPost.setConfig(requestConfig);
        List <NameValuePair> nvps = new ArrayList <NameValuePair>();
        StringBuffer paramsBuf = new StringBuffer() ;
        for(Entry<String, String> e : params.entrySet()) {
            nvps.add(new BasicNameValuePair(e.getKey(), e.getValue()));
            paramsBuf.append("&").append(e.getKey()).append("=").append(e.getValue()) ;
        }
        httpPost.setEntity(new UrlEncodedFormEntity(nvps, "UTF-8"));
        try {
//          報文引數27：&id=jn-3-767744&groupPlatProTerminalId=119667&extend=uwJZ8j3CkpGPL4rM5J6KJhjR99O7yAe3BAGLS8ooI8ijNqKHfzTaK6W9wQvjZEVOmWJ3HxFb2O9D
//          wDbe3++UiQ==&xxtCode=370000&terminalType=1&role=3&type=3
            System.out.println("post請求報文地址：" + httpUrl+"?"+paramsBuf.toString()) ;
            CloseableHttpResponse response = httpclient.execute(httpPost);
            InputStream content = response.getEntity().getContent() ;
            in = new BufferedReader(new InputStreamReader(content, "UTF-8"));
//          in = new BufferedReader(new InputStreamReader(content, "GBK"));
//          in = new BufferedReader(new InputStreamReader(content));
            StringBuilder sb = new StringBuilder();
            String line = "" ;
            while ((line = in.readLine()) != null) {
                sb.append(line);
            }
            result = sb.toString() ;
            System.out.println("響應報文：" + result) ;
            //  響應報文：{"ret":0,"msg":"成功","callbackurl":"https://edu.10086.cn/test-sso/login?service=http%3A%2F%2F112.35.7.169%3A9010%2Feducloud%2Flogin%2Flogin%3Ftype%3D3%26mode%3D1%26groupId%3D4000573%26provincePlatformId%3D54","accesstoken":"2467946a-bee9-4d8c-8cce-d30181073b75"}Í
            //記錄報文日誌
            YdEduDao dao = SpringUtil.getBean(YdEduDao.class);
            dao.saveCallLog(httpUrl, paramsBuf.toString(), result);    // HJY_SERVICE_LOG

            return result ;
        } catch (Exception e) {
            e.printStackTrace() ;
        } finally {
            httpclient.close();
        }
        return null ;
    }

    public static JSONObject postData(String httpUrl, Object obj) throws Exception {
        JSONObject json = null;
        try{
        String result = post(httpUrl,obj);
             json = JSONObject.parseObject(result);
        }catch(TimeoutException e){
            System.out.println("請求超時了："+httpUrl);
            throw e;
        }finally {
            return json ;
        }
    }

    public static String post(String httpUrl, Object obj) throws Exception {
        Map<String, String>  params = getParamData(obj);
        String result = null ;

        try {
            result = post(httpUrl,params);
            return result ;
        } catch (Exception e) {
            e.printStackTrace() ;
        } finally {
            httpclient.close();
        }
        return null ;
    }


    private static Map<String, String>  getParamData(Object obj) {

        Class cla = obj.getClass();
        Map<String, String> map = new HashMap<String, String>();
        Method[] methods = cla.getDeclaredMethods();
        try {
            for (Method m : methods) {
                String mname = m.getName();
                if (mname.startsWith("get")) {
                    String name = mname.substring(3, mname.length());// 擷取欄位
                    name = name.substring(0, 1).toLowerCase()
                            + name.substring(1, name.length());// 把首字母變小寫
                    String value = m.invoke(obj)==null?"":m.invoke(obj).toString();
                    if(cla.equals(YdOrderRelationshipInfoSyncItem.class)&&name.equals("unionId")&&(value==null||value.equals(""))){
                        continue;
                    }
                    map.put(name,value);// 取值
                }

            }
            Class superclass = cla.getSuperclass();
            while (!superclass.equals(Object.class)) {
                Method[] superclassmethods = superclass.getDeclaredMethods();
                for (Method m : superclassmethods) {
                    String mname = m.getName();
                    if (mname.startsWith("get")) {
                        String name = mname.substring(3, mname.length());// 擷取欄位
                        name = name.substring(0, 1).toLowerCase()
                                + name.substring(1, name.length());// 把首字母變小寫
                        String value = m.invoke(obj)==null?"":m.invoke(obj).toString();

                        if((cla.equals(OrderInfoSyncItem.class)||cla.equals(AccountPasswordInfoSyncItem.class)||cla.equals(YdOrderRelationshipInfoSyncItem.class))&&name.equals("operation"))
                            continue;

                        map.put(name,value);// 取值
                    }

                }
                superclass = superclass.getSuperclass();

            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        return map;
    }

    public static CloseableHttpClient createSSLClientDefault(){

        try {
            //SSLContext sslContext = new SSLContextBuilder().loadTrustMaterial(null, new TrustStrategy() {
            // 在JSSE中，證書信任管理器類就是實現了介面X509TrustManager的類。我們可以自己實現該介面，讓它信任我們指定的證書。
            // 建立SSLContext物件，並使用我們指定的信任管理器初始化
            //信任所有
                X509TrustManager x509mgr = new X509TrustManager() {

                    //　　該方法檢查客戶端的證書，若不信任該證書則丟擲異常
                    public void checkClientTrusted(X509Certificate[] xcs, String string) {
                    }
                    // 　　該方法檢查服務端的證書，若不信任該證書則丟擲異常
                    public void checkServerTrusted(X509Certificate[] xcs, String string) {
                    }
                    // 　返回受信任的X509證書陣列。
                    public X509Certificate[] getAcceptedIssuers() {
                        return null;
                    }
                };
                SSLContext sslContext = SSLContext.getInstance("TLS");
                sslContext.init(null, new TrustManager[] { x509mgr }, null);
                ////建立HttpsURLConnection物件，並設定其SSLSocketFactory物件
                SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(sslContext, SSLConnectionSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER);

            //  HttpsURLConnection物件就可以正常連線HTTPS了，無論其證書是否經權威機構的驗證，只要實現了介面X509TrustManager的類MyX509TrustManager信任該證書。
            return HttpClients.custom().setSSLSocketFactory(sslsf).build();


        } catch (KeyManagementException e) {

            e.printStackTrace();

        } catch (NoSuchAlgorithmException e) {

            e.printStackTrace();

        } catch (Exception e) {

            e.printStackTrace();

        }

        // 建立預設的httpClient例項.
        return  HttpClients.createDefault();

    }



}

另外，在針對http進行升級時，在HTTPS的證書未經權威機構認證的情況下，訪問HTTPS站點的兩種方法，一種方法是把該證書匯入到Java的TrustStore檔案中，另一種是自己實現並覆蓋JSSE預設的證書信任管理器類。兩種方法各有優缺點，第一種方法不會影響JSSE的安全性，但需要手工匯入證書；第二種方法雖然不用手工匯入證書，但需要小心使用，否則會帶來一些安全隱患。