项目需求：

jsonp是从前台js的角度考虑，通过Ajax调用springMVC的接口。同一个ip、同一个网络协议、同一个端口，三者都满足就是同一个域，否则就是跨域问题了。首页广告需要一个轮播的效果，取后台数据json格式。上篇博客介绍了使用jsonp来解决跨域，现在有个新的方法来解决，那就是：ajax请求地址改为自己系统的后台地址，之后在自己的后台用HttpClient请求url。封装好的跨域请求url工具类。封装一个get一个POST即可。

两者的区别就在于，jsonp是基于客户端的跨域解决。而httpclient是基于服务端的跨域解决。

我现在有两个maven项目：

Taotao-rest（8081端口）

要使用httpclient需要在maven中引用（portal）：

<!-- httpclient --><dependency> ???<groupId>org.apache.httpcomponents</groupId> ???<artifactId>httpclient</artifactId></dependency>

rest项目中写了个后台的服务调广告的数据，在portal项目中的service层来调用rest项目中的controller层提供的服务。

httpclient工作图解：

核心代码展示：

(portal项目)contentcontroller.java

@Controllerpublic class ContentController { ???@Autowired ???private ContentService contentService; ???????????//getdata ???@RequestMapping("/content/{cid}") ???@ResponseBody ???public TaotaoResult getConentList(@PathVariable Long cid){ ???????????????try { ???????????List<TbContent> list=contentService.getContentList(cid); ???????????return TaotaoResult.ok(list); ???????} catch (Exception e) { ???????????e.printStackTrace(); ???????????return TaotaoResult.build(500, ExceptionUtil.getStackTrace(e)); ???????} ???}}

(portal项目)HttpClientUtil.java

package com.taotao.common.utils;import java.io.IOException;import java.net.URI;import java.util.ArrayList;import java.util.List;import java.util.Map;import org.apache.http.NameValuePair;import org.apache.http.client.entity.UrlEncodedFormEntity;import org.apache.http.client.methods.CloseableHttpResponse;import org.apache.http.client.methods.HttpGet;import org.apache.http.client.methods.HttpPost;import org.apache.http.client.utils.URIBuilder;import org.apache.http.entity.ContentType;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;public class HttpClientUtil { ???public static String doGet(String url, Map<String, String> param) { ???????// 创建Httpclient对象 ???????CloseableHttpClient httpclient = HttpClients.createDefault(); ???????String resultString = ""; ???????CloseableHttpResponse response = null; ???????try { ???????????// 创建uri ???????????URIBuilder builder = new URIBuilder(url); ???????????if (param != null) { ???????????????for (String key : param.keySet()) { ???????????????????builder.addParameter(key, param.get(key)); ???????????????} ???????????} ???????????URI uri = builder.build(); ???????????// 创建http GET请求 ???????????HttpGet httpGet = new HttpGet(uri); ???????????// 执行请求 ???????????response = httpclient.execute(httpGet); ???????????// 判断返回状态是否为200 ???????????if (response.getStatusLine().getStatusCode() == 200) { ???????????????resultString = EntityUtils.toString(response.getEntity(), "UTF-8"); ???????????} ???????} catch (Exception e) { ???????????e.printStackTrace(); ???????} finally { ???????????try { ???????????????if (response != null) { ???????????????????response.close(); ???????????????} ???????????????httpclient.close(); ???????????} catch (IOException e) { ???????????????e.printStackTrace(); ???????????} ???????} ???????return resultString; ???} ???public static String doGet(String url) { ???????return doGet(url, null); ???} ???public static String doPost(String url, Map<String, String> param) { ???????// 创建Httpclient对象 ???????CloseableHttpClient httpClient = HttpClients.createDefault(); ???????CloseableHttpResponse response = null; ???????String resultString = ""; ???????try { ???????????// 创建Http Post请求 ???????????HttpPost httpPost = new HttpPost(url); ???????????// 创建参数列表 ???????????if (param != null) { ???????????????List<NameValuePair> paramList = new ArrayList<>(); ???????????????for (String key : param.keySet()) { ???????????????????paramList.add(new BasicNameValuePair(key, param.get(key))); ???????????????} ???????????????// 模拟表单 ???????????????UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList); ???????????????httpPost.setEntity(entity); ???????????} ???????????// 执行http请求 ???????????response = httpClient.execute(httpPost); ???????????resultString = EntityUtils.toString(response.getEntity(), "utf-8"); ???????} catch (Exception e) { ???????????e.printStackTrace(); ???????} finally { ???????????try { ???????????????response.close(); ???????????} catch (IOException e) { ???????????????// TODO Auto-generated catch block ???????????????e.printStackTrace(); ???????????} ???????} ???????return resultString; ???} ???public static String doPost(String url) { ???????return doPost(url, null); ???} ???????public static String doPostJson(String url, String json) { ???????// 创建Httpclient对象 ???????CloseableHttpClient httpClient = HttpClients.createDefault(); ???????CloseableHttpResponse response = null; ???????String resultString = ""; ???????try { ???????????// 创建Http Post请求 ???????????HttpPost httpPost = new HttpPost(url); ???????????// 创建请求内容 ???????????StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON); ???????????httpPost.setEntity(entity); ???????????// 执行http请求 ???????????response = httpClient.execute(httpPost); ???????????resultString = EntityUtils.toString(response.getEntity(), "utf-8"); ???????} catch (Exception e) { ???????????e.printStackTrace(); ???????} finally { ???????????try { ???????????????response.close(); ???????????} catch (IOException e) { ???????????????// TODO Auto-generated catch block ???????????????e.printStackTrace(); ???????????} ???????} ???????return resultString; ???}}