Spring 实现远程访问详解——httpclient

╰半橙微兮° 2022-08-21 06:40 235阅读 0赞

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][Spring _httpinvoker]》和《[Spring 实现远程访问详解——rmi][Spring _rmi]》。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>

## 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][http_download.csdn.net_detail_a123demi_9495928]

[Spring _httpinvoker]: http://blog.csdn.net/a123demi/article/details/51190527
[Spring _rmi]: http://blog.csdn.net/a123demi/article/details/51179083
[http_download.csdn.net_detail_a123demi_9495928]: http://download.csdn.net/detail/a123demi/9495928