跨域问题浅析

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什么是跨域问题

URL 说明是否允许跨域 http:// www.a.com/a.js
http:// www.a.com/b.js 同一域名下允许 http:// www.a.com/lab/a.js
http:// www.a.com/script/b.js 同一域名下不同文件夹允许 http:// www.a.com:8000/a.js
http: //www.a.com/b.js 同一域名，不同端口不允许 http: //www.a.com/a.js
https: //www.a.com/b.js 同一域名，不同协议不允许 http:// www.a.com/a.js
http:// 70.32.92.74/b.js 域名和域名对应ip 不允许 http:// www.a.com/a.js
http:// script.a.com/b.js 主域相同，子域不同不允许 http:// www.a.com/a.js
http:// a.com/b.js 同一域名，不同二级域名（同上）不允许 http: //www.b.com/a.js
http: //www.a.com/b.js 不同域名不允许

跨域问题的本质

进程间通信的问题

Java后端解决方式

对于spring 4.2.5以上版本

    /**     * 支持跨域     *      * @return     */    @Bean    public WebMvcConfigurer corsConfigurer() {        return new WebMvcConfigurerAdapter() {            @Override            public void addCorsMappings(CorsRegistry registry) {                registry.addMapping("/**").allowedOrigins("*").allowedMethods("PUT", "DELETE", "GET", "POST")                        .allowCredentials(false).maxAge(3600);                registry.addMapping("/login").allowedOrigins("*").allowedMethods("PUT", "DELETE", "GET", "POST")                        .allowCredentials(false).maxAge(3600);            }        };    }

对于spring 4.2.5以下版本
需要写filter来完成

package com.test.filter;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;/** * * @author hyson.han */public class CorsFilter implements Filter {    @Override    public void init(FilterConfig filterConfig) throws ServletException {    }    @Override    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain chain)            throws IOException, ServletException {        HttpServletResponse response = (HttpServletResponse) servletResponse;        response.setHeader("Access-Control-Allow-Origin", "*");        response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");        response.setHeader("Access-Control-Max-Age", "3600");        response.setHeader("Access-Control-Allow-Headers", "x-requested-with,Authorization");        response.setHeader("Access-Control-Allow-Credentials", "true");        chain.doFilter(servletRequest, servletResponse);    }    @Override    public void destroy() {    }}

web.xml添加如下配置

<filter>        <filter-name>cors</filter-name>        <filter-class>com.test.filter.CorsFilter</filter-class></filter><filter-mapping>        <filter-name>cors</filter-name>        <url-pattern>/*</url-pattern></filter-mapping>

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