使用Httpclient 完美解决服务端跨域问题
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
- @Controller
- public 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;
- }
- }
(rest项目)contentserviceimpl.java
- @Service
- public class ContentServiceImpl implements ContentService {
- //service 写活,读配置文件
- @Value("${REST_BASE_URL}")
- private String REST_BASE_URL;
- @Value("${REST_CONTENT_URL}")
- private String REST_CONTENT_URL;
- @Value("${REST_CONTENT_AD1_CID}")
- private String REST_CONTENT_AD1_CID;
- @Override
- public String getAd1List() {
- //调用服务获得数据 跨域请求:http://localhost:8081/content/89
- String json = HttpClientUtil.doGet(REST_BASE_URL + REST_CONTENT_URL + REST_CONTENT_AD1_CID);
- //把json转换成java对象
- TaotaoResult taotaoResult = TaotaoResult.formatToList(json, TbContent.class);
- //取data属性,内容列表
- List<TbContent> contentList = (List<TbContent>) taotaoResult.getData();
- //把内容列表转换成AdNode列表
- List<AdNode> resultList = new ArrayList<>();
- for (TbContent tbContent : contentList) {
- AdNode node = new AdNode();
- node.setHeight(240);
- node.setWidth(670);
- node.setSrc(tbContent.getPic());
- node.setHeightB(240);
- node.setWidthB(550);
- node.setSrcB(tbContent.getPic2());
- node.setAlt(tbContent.getSubTitle());
- node.setHref(tbContent.getUrl());
- resultList.add(node);
- }
- //需要把resultList转换成json数据
- String resultJson = JsonUtils.objectToJson(resultList);
- return resultJson;
- }
- }
(rest项目)indexcontroller
- @Autowired
- private ContentService contentService;
- @RequestMapping("/index")
- public String showIndex(Model model){
- String json=contentService.getAd1List();
- model.addAttribute("ad1",json);
- return "index";
- }