spring boot 跨域訪問處理

1. 問題場景：由於項目中使用到跨域訪問，今天也得到高人指點，所以寫出來分享給大家。可能是考慮到前后端分離，前端后端服務器不在一台機器上，出現這種跨域訪問的情況。正常情況下本地訪問是沒有問題，但是遇到這種非同一台服務器的情況下，就會報錯 Access-Control-Allow-Origin 。具體報錯內容不記得了。
2. 問題解決方案一：采用添加攔截器的方式對請求添加跨域訪問的頭，允許跨域訪問。

   package com.meicloud.interceptor;
   
   import javax.servlet.http.HttpServletRequest;
   import javax.servlet.http.HttpServletResponse;
   
   import org.apache.log4j.Logger;
   import org.springframework.web.servlet.ModelAndView;
   import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
   
   public class CommonInterceptor extends HandlerInterceptorAdapter  {
   
       private final static  Logger logger = Logger.getLogger(CommonInterceptor.class);
       
       @Override
       public boolean preHandle(HttpServletRequest request,HttpServletResponse response, Object handler) throws Exception {
           logger.info("添加跨域訪問頭配置，Access-Control-Allow-Origin:*");
           //跨域訪問CORS
           response.addHeader("Access-Control-Allow-Origin", "*");
           response.addHeader("Access-Control-Allow-Methods", "POST,GET,OPTIONS,PUT,DELETE,HEAD");
           response.addHeader("Access-Control-Allow-Headers", "S_ID,content-type");
           response.addHeader("Access-Control-Max-Age", "3600000");
           response.addHeader("Access-Control-Allow-Credentials", "true");
           
           //讓請求，不被緩存，
           response.setHeader("Cache-Control", "no-cache");  
           response.setHeader("Cache-Control", "no-store");  
           response.setHeader("Pragma", "no-cache");  
           response.setDateHeader("Expires", 0); 
           
           logger.debug("==================================preHandle");
           return true;
       }
       
       @Override
       public void postHandle(HttpServletRequest request,
               HttpServletResponse response, Object handler,
               ModelAndView modelAndView) throws Exception {
           logger.debug("==================================postHandle");
       }
       
       
       @Override
       public void afterCompletion(HttpServletRequest request,
               HttpServletResponse response, Object handler, Exception ex)
               throws Exception {
           logger.debug("==================================afterCompletion");
       }
   }

   上面是攔截器內容，下面是對攔截器的配置。

   package com.meicloud.config;
   
   import org.springframework.context.annotation.ComponentScan;
   import org.springframework.context.annotation.Configuration;
   import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
   import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
   import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
   import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
   
   import com.meicloud.interceptor.CommonInterceptor;
   
   @ComponentScan
   @Configuration
   public class WebMvcConfig extends WebMvcConfigurerAdapter {
       
       @Override
       public void addInterceptors(InterceptorRegistry registry) {
           // TODO Auto-generated method stub
           registry.addInterceptor(new CommonInterceptor()).addPathPatterns("/getDOC");
       }
     
   }

   然后就可以在controller中使用他了，下面是我的controller

   @ResponseBody
   @RequestMapping(value="/getDOC",method=RequestMethod.POST)
   public BaseReturn getDOC(@RequestBody MailEntity mailEntity, HttpServletRequest request, HttpServletResponse response, HttpSession httpSession){
   log.info("excute controllor HomeController.getDOC");
   BaseReturn baseReturn = new BaseReturn();
   
   String name = mailEntity.getName();
   String company = mailEntity.getCompany();
   String departments = mailEntity.getDepartments();
   String job = mailEntity.getJob();
   String email = mailEntity.getEmail();
   String phone = mailEntity.getPhone();
   String doc = mailEntity.getDoc();
   
   try {
   if(name==null||name.equals("")){
   throw new CommenException("姓名不能為空!");
   }
   if(email==null||email.equals("")){
   throw new CommenException("Email不能為空!");
   }
   if(phone==null||phone.equals("")){
   throw new CommenException("電話號碼不能為空!");
   }
   if(doc==null||doc.equals("")){
   throw new CommenException("文檔不能為空!");
   }
   } catch (Exception e1) {
   baseReturn.setCode(ReturnType.FAIL);
   baseReturn.setMsg(e1.getMessage());
   log.error(e1.getMessage());
   return baseReturn;
   }
   
   try {
   // iMailClent.sendMail(mailEntity);
   iMailClent.sendHtmlMail(mailEntity);
   baseReturn.setCode(ReturnType.SUCCESS);
   } catch (Exception e) {
   e.printStackTrace();
   baseReturn.setCode(ReturnType.FAIL);
   baseReturn.setMsg("發送郵件失敗！");
   log.error(e.getMessage());
   }
   
   return baseReturn;
   }
   

   接下來是前端的調用，前端采用ajax post 請求

   var params = {
                             name:name,
                             company:company,
                             departments:departments,
                             job:job,
                             email:email,
                             phone:phone,
                             doc:'/doc/api.doc'
                     };
   
   
   var type = 'POST';
   var url = Config.host + url;
   
   
   $.ajax({
           url : url,
           data : JSON.stringify(params),
           type : type,
           contentType : "application/json",
           async : false,
           success : function(data) {
               //TODO 成功
           },
           error : function(data) {
               //TODO 失敗
           }
       });

    

3. 問題解決方案二：使用 JSONP 來實現跨域訪問。直接上代碼，前端代碼為：

   url = 'http://localhost:9999/getDOC' + '?name=' + params.name 
               + '&company=' + params.company
               + '&departments=' + params.departments + '&job=' + params.job
               + '&email=' + params.email + '&phone=' + params.phone + '&doc='
               + params.doc;
   
   $.ajax({
           url : url,
           type : 'get',
           async : false,
           dataType : "jsonp",
           jsonpCallback : "callback",
           success : function(data) {
               //TODO 成功
           },
           error : function(data) {
               //TODO 失敗
           }
       });

   限制調用方式為 get ，數據類型為 jsonp。后端也必須響應 JSONPObject 對象。

   @ResponseBody
       @RequestMapping(value="/getDOC",method=RequestMethod.GET)
       public JSONPObject getDOC(HttpServletRequest request,String callback){
           
           BaseReturn baseReturn = new BaseReturn();
           
           String name = request.getParameter("name");
           String company = request.getParameter("company");
           String departments = request.getParameter("departments");
           String job = request.getParameter("job");
           String email = request.getParameter("email");
           String phone = request.getParameter("phone");
           String doc = request.getParameter("doc");
           
           try {
               if(name==null||name.equals("")){
                   throw new CommenException("姓名不能為空!");
               }
               if(email==null||email.equals("")){
                   throw new CommenException("Email不能為空!");
               }
               if(phone==null||phone.equals("")){
                   throw new CommenException("電話號碼不能為空!");
               }
               if(doc==null||doc.equals("")){
                   throw new CommenException("文檔不能為空!");
               }
           } catch (Exception e1) {
               baseReturn.setCode(ReturnType.FAIL);
               baseReturn.setMsg(e1.getMessage());
               log.error(e1.getMessage());
               return new JSONPObject(callback, baseReturn);
           }
           
           MailEntity mailEntity = new MailEntity();
           mailEntity.setCompany(company);
           mailEntity.setDepartments(departments);
           mailEntity.setDoc(doc);
           mailEntity.setEmail(email);
           mailEntity.setJob(job);
           mailEntity.setName(name);
           mailEntity.setPhone(phone);
           
           
           try {
                iMailClent.sendHtmlMail(mailEntity);
               baseReturn.setCode(ReturnType.SUCCESS);
           } catch (Exception e) {
               e.printStackTrace();
               baseReturn.setCode(ReturnType.FAIL);
               baseReturn.setMsg("發送郵件失敗！");
               log.error(e.getMessage());
           }
           
           return new JSONPObject(callback, baseReturn);
       }
       

    

4. 今天得到高人指點，原來有一種更加簡便的方法，可以實現。不過原理肯定都是一樣的，通過給請求添加消息頭來設置跨域訪問，這點是無疑的。新的解決辦法就是給controller或方法添加 @CrossOrigin 注解，具體詳情請參考：http://spring.io/blog/2015/06/08/cors-support-in-spring-framework

   @ResponseBody
       @RequestMapping(value="/getDOC",method=RequestMethod.POST)
       @CrossOrigin //使用注解方式添加跨域訪問消息頭
       public BaseReturn getDOC(@RequestBody MailEntity mailEntity, HttpServletRequest request, HttpServletResponse response, HttpSession httpSession){
           log.info("excute controllor HomeController.getDOC");

   就這么多了吧，在網上看到還有添加過濾器的，當然都是差不多的做法。