現在我們很多項目都是基於Java的REST結構風格前後端分離，在前端訪問後端的時候就存在跨域，這個時候後端接口不處理就會存在訪問不了。上代碼！

　　1、創建一個Filter 在web.xml中配置

<filter>
        <filter-name>xssAndSqlFilter</filter-name>
        <filter-class>com.tzdr.btc.user.filter.XssAndSqlFilter</filter-class>
        <!--過濾掉 靜態資源文件 指定字符串  多個值用英文逗號隔開
 
-->
        <init-param>
            <param-name>excludedPages</param-name>
            <param-value>/tesra/</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>xssAndSqlFilter</filter-name>
        <url-pattern
 
>/*</url-pattern>
    </filter-mapping>

2、在Filter的doFiler方法中添加設置

@Override  
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {  
        boolean isExcludedPage = Boolean.TRUE;
        HttpServletResponse httpResponse 
 
= (HttpServletResponse) response;
        HttpServletRequest request1 = (HttpServletRequest) request;
        //*表示允許所有域名跨域
        httpResponse.setHeader("Access-Control-Allow-Origin", request1.getHeader("Origin"));
        httpResponse.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");
        httpResponse.setHeader("Access-Control-Max-Age", "0");
        httpResponse.setHeader("Access-Control-Allow-Headers", "Origin, No-Cache, X-Requested-With, If-Modified-Since, Pragma, Last-Modified, Cache-Control, Expires, Content-Type, X-E4M-With,userId,token,Access-Control-Allow-Headers");
        httpResponse.setHeader("Access-Control-Allow-Credentials", "true");//這個是設置運行攜帶cookie
        httpResponse.setHeader("XDomainRequestAllowed","1");
        //判斷是否在過濾url之外
        for (String page : excludedPageArray) {
            if(((HttpServletRequest) request).getServletPath().contains(page)){
                isExcludedPage = Boolean.FALSE;
                break;
            }
        }
        //在過濾url之外
        if (isExcludedPage) {
            XssAndSqlHttpServletRequestWrapper xssRequest = new XssAndSqlHttpServletRequestWrapper((HttpServletRequest) request);
            chain.doFilter(xssRequest, response);
        }
        else{
            chain.doFilter(request, response);
        }
    }

這樣完成以後 再訪問接口就能成功訪問了。

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Java設置接口跨域