httpClient请求转发个人理解

最近有个项目需要做一个请求转发的功能场景如下：

公司A 、公司B（本公司）、公司C、公司D

A访问B、B从C和D中拿数据，

A访问B的时候有个一下三种情况

1、get方式

2、post方式参数格式form-data

3、post方式参数格式json

get方式解决代码

public static void httpGet(String apiReal, HttpServletRequest request, HttpServletResponse response,
                           List<NameValuePair> additionalMap) throws UnsupportedEncodingException, URISyntaxException, UnknownHostException {
    CloseableHttpClient httpClient = SSLUtils.createSSLClientDefault();
    
    URIBuilder uriBuilder = new URIBuilder(apiReal);
    //普通参数赋值
    Enumeration<String> parameterNames = request.getParameterNames();
    while (parameterNames.hasMoreElements()) {
        String parameterName = parameterNames.nextElement();
        for (String value : request.getParameterValues(parameterName)) {
            if (value != null && !"null".equals(value)) {
                BasicNameValuePair bNVP = new BasicNameValuePair(parameterName, value);
                additionalMap.add(bNVP);
            }
        }
    }
    
    uriBuilder.setParameters(additionalMap);
    //创建HttpGet对象，设置URL地址
    HttpGet httpGet = new HttpGet(uriBuilder.build());
    //请求头参数赋值
    Enumeration<String> headerNames = request.getHeaderNames();
    while (headerNames.hasMoreElements()) {
        String headerName = headerNames.nextElement();
        if (!"host".equalsIgnoreCase(headerName)) {
            httpGet.addHeader(headerName, request.getHeader(headerName));
        }
    }
    
    HttpResponse httpResponse = null;
    try {
        //发送请求
        httpResponse = httpClient.execute(httpGet);
        if (httpResponse != null) {
            HttpEntity responseEntity = httpResponse.getEntity();
            if (responseEntity != null) {
                // httpResponse   请求结果赋值给 response
                responseEntity.writeTo(response.getOutputStream());
            }
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
    if (httpResponse != null) {
        response.setStatus(httpResponse.getStatusLine().getStatusCode());
        HeaderIterator headerIterator = httpResponse.headerIterator();
        while (headerIterator.hasNext()) {
            Header header = headerIterator.nextHeader();
            if ("Content-Type".equals(header.getName())) {
                response.setHeader(header.getName(), header.getValue());
            }
        }
    }
}

post方式参数格式form-data：

public static void httpPost(String apiReal, HttpServletRequest request, HttpServletResponse response,
                            List<NameValuePair> additionalMap) {
    CloseableHttpClient httpClient = SSLUtils.createSSLClientDefault();
    HttpPost httpPost = new HttpPost(apiReal);
    
    Enumeration<String> headerNames = request.getHeaderNames();
    while (headerNames.hasMoreElements()) {
        String headerName = headerNames.nextElement();
        if (!(headerName.equalsIgnoreCase("host") || headerName.equalsIgnoreCase("content-length"))) {
            httpPost.addHeader(headerName, request.getHeader(headerName));
        }
    }
    
    List<NameValuePair> params = new ArrayList<NameValuePair>();
    Enumeration<String> parameterNames = request.getParameterNames();
    while (parameterNames.hasMoreElements()) {
        String parameterName = parameterNames.nextElement();
        for (String value : request.getParameterValues(parameterName)) {
            if (value != null && !value.equals("null")) params.add(new BasicNameValuePair(parameterName, value));
        }
    }
    
    HttpResponse httpResponse = null;
    try {
        UrlEncodedFormEntity entity = new UrlEncodedFormEntity(params, "UTF-8");
        httpPost.setEntity(entity);
        httpResponse = httpClient.execute(httpPost);
        if (httpResponse != null) {
            HttpEntity responseEntity = httpResponse.getEntity();
            if (responseEntity != null) {
                log.info(responseEntity.toString());
                responseEntity.writeTo(response.getOutputStream());
            }
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
    if (httpResponse != null) {
        response.setStatus(httpResponse.getStatusLine().getStatusCode());
        HeaderIterator headerIterator = httpResponse.headerIterator();
        while (headerIterator.hasNext()) {
            Header header = headerIterator.nextHeader();
            if (header.getName().equals("Content-Type")) {
                response.setHeader(header.getName(), header.getValue());
            }
        }
        
    }
}

post方式参数格式json：

json格式会有一个问题，json存放在request流中，request的流只能读取一边（默认情况），第二次读取会出现流为空的问题，所以就要解决流不能重复获取，

我在网上找了个博客https://www.cnblogs.com/panchanggui/p/12297860.html通过HttpServletRequestWrapper解决，流数据可以重复获取之后就可以通过下列代码写到新的请求里

　　//bodyParam是流
   StringEntity bodyData = new StringEntity(bodyParam, "UTF-8");
   httpPost.setEntity(bodyData);

如何获取流文件？

   public static JSONObject getJsonObjectByRequest(HttpServletRequest request) {
        StringBuffer sb = new StringBuffer();
        String line = null;
        try {
            BufferedReader reader = request.getReader();
            while ((line = reader.readLine()) != null) {
                sb.append(line);
            }
        } catch (Exception e) { /*report an error*/ }
        String jsonString = sb.toString().replaceAll("\s", "").replaceAll("
", "");
        JSONObject jsonObject = JSON.parseObject(jsonString);
        return jsonObject;
    }

通用工具类：

import org.apache.http.HttpResponse;
import org.apache.http.conn.ConnectionKeepAliveStrategy;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.conn.ssl.TrustStrategy;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.protocol.HttpContext;
import org.apache.http.ssl.SSLContextBuilder;

import javax.net.ssl.SSLContext;
import java.security.KeyManagementException;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;

public class SSLUtils {
    
    public static CloseableHttpClient createSSLClientDefault() {
        
        ConnectionKeepAliveStrategy myStrategy = new ConnectionKeepAliveStrategy() {
            @Override
            public long getKeepAliveDuration(HttpResponse response, HttpContext context) {
                return 5 * 1000;
            }
            
        };
        
        try {
            SSLContext sslContext = new SSLContextBuilder().loadTrustMaterial(null, new TrustStrategy() {
                //信任所有
                @Override
                public boolean isTrusted(X509Certificate[] chain, String authType) throws CertificateException {
                    return true;
                }
            }).build();
            SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(sslContext);
            return HttpClients.custom()
                    .setConnectionManagerShared(true)
                    .setSSLSocketFactory(sslsf)
                    .setKeepAliveStrategy(myStrategy)
                    .evictExpiredConnections()
                    .build();
        } catch (KeyManagementException e) {
            e.printStackTrace();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (KeyStoreException e) {
            e.printStackTrace();
        }
        return HttpClients.createDefault();
    }
    
}