Spring 实现远程访问详解——HttpClient

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上两章我们分别利用Spring rmi和httpinvoker实现的远程访问功能，具体见《Spring 实现远程访问详解——httpinvoker》和《Spring 实现远程访问详解——rmi》和《Spring 实现远程访问详解——webservice》

本章将通过apache httpclient实现远程访问。说得简单就是直接通过spring requestmapping即请求映射url访问远程服务。

1. 远程访问流程

1) 服务器在控制器定义远程访问请求映射路径

2) 客户端通过apache httpclient的 httppost方式访问远程服务

2. Httpclient方式具体实现

1) maven引入依赖

<dependency>                  <groupId>org.apache.httpcomponents</groupId>                  <artifactId>httpclient</artifactId>                  <version>4.5.2</version>          </dependency></span>

2) 服务器在控制器定义远程访问请求映射路径

    @RequestMapping(value="/httpClientTest")      @ResponseBody      public BaseMapVo httpClientTest(String name, String password){         BaseMapVo vo = new BaseMapVo();         List<User> users = userService.getUserByAcount(name, password);         vo.addData("user", users);         vo.setRslt("success");         return vo;

3) 客户端定义httpClient

package com.lm.core.util;        import java.io.ByteArrayOutputStream;  import java.io.IOException;  import java.io.InputStream;  importjava.io.UnsupportedEncodingException;  import java.util.ArrayList;  import java.util.HashMap;  import java.util.List;  import java.util.Map;     import org.apache.http.HttpResponse;  import org.apache.http.NameValuePair;  importorg.apache.http.client.ClientProtocolException;  importorg.apache.http.client.entity.UrlEncodedFormEntity;  importorg.apache.http.client.methods.CloseableHttpResponse;  importorg.apache.http.client.methods.HttpPost;  import org.apache.http.impl.client.CloseableHttpClient;  importorg.apache.http.impl.client.HttpClients;  importorg.apache.http.message.BasicNameValuePair;     public class HttpClientUtil implementsRunnable {     /**      * 不能在主线程中访问网络所以这里另新建了一个实现了Runnable接口的Http访问类      */     private String name;     private String password;     private String path;        public HttpClientUtil(String name, String password,String path) {         // 初始化用户名和密码         this.name = name;         this.password = password;         this.path = path;      }        @Override     public void run() {         // 设置访问的Web站点         // 设置Http请求参数         Map<String, String> params = new HashMap<String, String>();         params.put("name", name);         params.put("password", password);            String result = sendHttpClientPost(path, params, "utf-8");         // 把返回的接口输出         System.out.println(result);      }        /**      * 发送Http请求到Web站点      *      * @param path      *            Web站点请求地址      * @param map      *            Http请求参数      * @param encode      *            编码格式      * @return Web站点响应的字符串      */     private String sendHttpClientPost(String path, Map<String, String>map,             String encode) {         List<NameValuePair> list = new ArrayList<NameValuePair>();          if (map != null && !map.isEmpty()) {             for (Map.Entry<String, String> entry : map.entrySet()) {                  // 解析Map传递的参数，使用一个键值对对象BasicNameValuePair保存。                  list.add(newBasicNameValuePair(entry.getKey(), entry                          .getValue()));             }         }         HttpPost httpPost = null;         CloseableHttpClient client = null;         InputStream inputStream = null;                  try {             // 实现将请求的参数封装封装到HttpEntity中。             UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list, encode);             // 使用HttpPost请求方式             httpPost = new HttpPost(path);             // 设置请求参数到Form中。             httpPost.setEntity(entity);             // 实例化一个默认的Http客户端             client = HttpClients.createDefault();  //            HttpClient client = newDefaultHttpClient();             // 执行请求，并获得响应数据             CloseableHttpResponse httpResponse = client.execute(httpPost);             // 判断是否请求成功，为200时表示成功，其他均问有问题。             System.err.println("status:"+httpResponse.getStatusLine().getStatusCode());             try{                       if(httpResponse.getStatusLine().getStatusCode() == 200) {                           // 通过HttpEntity获得响应流                           inputStream =httpResponse.getEntity().getContent();                           returnchangeInputStream(inputStream, encode);                       }             }finally{                      if( null != httpResponse){                                httpResponse.close();                      }                                           if(null != inputStream){                                inputStream.close();                      }             }         } catch (UnsupportedEncodingException e) {             e.printStackTrace();         } catch (ClientProtocolException e) {             e.printStackTrace();         } catch (IOException e) {             e.printStackTrace();         }finally{                  if(null != client){                            try {                                                 client.close();                                       }catch (IOException e) {                                                 //TODO Auto-generated catch block                                                 e.printStackTrace();                                       }                  }         }         return "";      }        /**      * 把Web站点返回的响应流转换为字符串格式      *      * @param inputStream      *            响应流      * @param encode      *            编码格式      * @return 转换后的字符串      */     private String changeInputStream(InputStream inputStream, String encode){         ByteArrayOutputStream outputStream = new ByteArrayOutputStream();         byte[] data = new byte[1024];         int len = 0;         String result = "";         if (inputStream != null) {             try {                  while ((len =inputStream.read(data)) != -1) {                      outputStream.write(data, 0,len);                  }                  result = newString(outputStream.toByteArray(), encode);                } catch (IOException e) {                  e.printStackTrace();             }finally{                      if(outputStream != null){                                try {                                                          outputStream.close();                                                 }catch (IOException e) {                                                          //TODO Auto-generated catch block                                                          e.printStackTrace();                                                 }                      }             }         }         return result;      }     }

4) 客户端访问远程服务

@RequestMapping(value = "/httpClientTest")@ResponseBody      public BaseMapVo httpClientTest(String name, String password) {         BaseMapVo vo = new BaseMapVo();         long startDate = Calendar.getInstance().getTimeInMillis();         System.out.println("httpInvoker客户端开始调用" + startDate);         String path="http://127.0.0.1:8080/spring_remote_server/user/httpClientTest";         HttpClientUtil httpClientUtil = new  HttpClientUtil(name, password, path);         new Thread(httpClientUtil).start();  //     UserHttpService rmi = (UserHttpService)ApplicationContextUtil.getInstance().getBean("httpInvokerProxy");  //     rmi.getUserByAcount("张三", ":张三的密码");         System.out.println("httpInvoker客户端调用结束" +  (Calendar.getInstance().getTimeInMillis()-startDate));         vo.setRslt("sucess");         return vo;      }

代码下载：http://download.csdn.net/detail/a123demi/9495928

博文转自：http://blog.csdn.net/a123demi/article/details/51206079

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