Java跨域问题

一说

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带有#号、删除线、不操作、不执行字样的为提示或者备份bash，实际不执行

前情提示

系统：

jQuery ajax或者前后端分离，经常浏览器提示跨域，无法请求到数据。大致报错如下：

Access to XMLHttpRequest at 'http://127.0.0.1/xxoopi/MapTest' from origin 'http://127.0.0.1:8848' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

后端解决

一、自定义过滤器

package com.xxoo.test;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletResponse;

public class SimpleCORSFilter implements Filter{  
    @Override
    public void destroy() {
    	
    }
    
    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
            HttpServletResponse response = (HttpServletResponse) res;
            /* 允许跨域的主机地址 */
            response.setHeader("Access-Control-Allow-Origin", "*");
            /* 是否携带cookie */
            response.setHeader("Access-Control-Allow-Credentials", "true");
            /* 允许跨域的请求方法GET, POST, HEAD 等 */
            response.setHeader("Access-Control-Allow-Methods", "*");
            /* 重新预检验跨域的缓存时间 (s) */
            response.setHeader("Access-Control-Max-Age", "3600");
            /* 允许跨域的请求头 */
//            response.setHeader("Access-Control-Allow-Headers", "*");
            response.setHeader("Access-Control-Allow-Headers", "Authorization,Origin,X-Requested-With,Content-Type,Accept,"
                    + "content-Type,origin,x-requested-with,content-type,accept,authorization,token,id,X-Custom-Header,X-Cookie,Connection,User-Agent,Cookie,*");
            response.setHeader("Access-Control-Request-Headers", "Authorization,Origin, X-Requested-With,content-Type,Accept");
            response.setHeader("Access-Control-Expose-Headers", "*");
            
            chain.doFilter(req, res);
    }  
  
    @Override
    public void init(FilterConfig arg0) throws ServletException {
    	
    }
    
}

web.xml文件增加：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>xxoopi</display-name>
  <welcome-file-list>
    <welcome-file>/index.jsp</welcome-file>
  </welcome-file-list>
  <filter>
    <filter-name>cors</filter-name>
    <filter-class>com.xxoo.test.SimpleCORSFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>cors</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
  
</web-app>

二、使用三方依赖jar包

https://mvnrepository.com/artifact/com.thetransactioncompany/cors-filter

https://mvnrepository.com/artifact/com.thetransactioncompany/java-property-utils

将依赖包放入lib目录，web.xml增加如下：

<!-- 跨域配置-->
    <filter>
        <!-- The CORS filter with parameters -->
        <filter-name>CORS</filter-name>
        <filter-class>com.thetransactioncompany.cors.CORSFilter</filter-class>

        <!-- Note: All parameters are options, if omitted the CORS
             Filter will fall back to the respective default values.
          -->
        <init-param>
            <param-name>cors.allowGenericHttpRequests</param-name>
            <param-value>true</param-value>
        </init-param>

        <init-param>
            <param-name>cors.allowOrigin</param-name>
            <param-value>*</param-value>
        </init-param>

        <init-param>
            <param-name>cors.allowSubdomains</param-name>
            <param-value>false</param-value>
        </init-param>

        <init-param>
            <param-name>cors.supportedMethods</param-name>
            <param-value>GET, HEAD, POST, OPTIONS</param-value>
        </init-param>

        <init-param>
            <param-name>cors.supportedHeaders</param-name>
            <param-value>Accept, Origin, X-Requested-With, Content-Type, Last-Modified</param-value>
        </init-param>

        <!--<init-param>
          <param-name>cors.exposedHeaders</param-name>
          &lt;!&ndash;这里可以添加一些自己的暴露Headers   &ndash;&gt;
          <param-value>X-Test-1, X-Test-2</param-value>
        </init-param>-->

        <init-param>
            <param-name>cors.supportsCredentials</param-name>
            <param-value>true</param-value>
        </init-param>

        <init-param>
            <param-name>cors.maxAge</param-name>
            <param-value>3600</param-value>
        </init-param>

    </filter>

    <filter-mapping>
        <!-- CORS Filter mapping -->
        <filter-name>CORS</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>