CAS环境下的AJAX跨域

情况说明:

在单点登录的环境下，所有的文件上传都是通过webuploader上传到文件管理服务器。而webuploader的上传可以参考ajax的请求，相当于是跨域操作。

首先，跨域请求访问的问题，可以通过在文件服务器增加拦截器，修改请求头来解决。

package com.sdzn.util;
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 {
    public void doFilter(ServletRequest req,ServletResponse res,FilterChain chain) throws IOException,ServletException {
        HttpServletResponse response = (HttpServletResponse) res;
        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");
        chain.doFilter(req,res);
    }
    public void init(FilterConfig filterConfig) {
    }
    public void destroy() {
    }
}

而在CAS的环境下，跨域的请求还会面临登录验证的重定向，但是ajax是不支持重定向的，进而导致文件上传的不成功。

查阅众多资料，最后在看到 org.jasig.cas.client.authentication.AuthenticationFilter 才豁然开朗。

/**
 * Licensed to Jasig under one or more contributor license
 * agreements. See the NOTICE file distributed with this work
 * for additional information regarding copyright ownership.
 * Jasig licenses this file to you under the Apache License,* Version 2.0 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a
 * copy of the License at:
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,* software distributed under the License is distributed on
 * an "AS IS" BASIS,WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND,either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.jasig.cas.client.authentication;
import org.jasig.cas.client.util.AbstractCasFilter;
import org.jasig.cas.client.util.CommonUtils;
import org.jasig.cas.client.validation.Assertion;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
/**
 * Filter implementation to intercept all requests and attempt to authenticate
 * the user by redirecting them to CAS (unless the user has a ticket).
 * <p>
 * This filter allows you to specify the following parameters (at either the context-level or the filter-level):
 * <ul>
 * <li><code>casServerLoginUrl</code> - the url to log into CAS,i.e. https://cas.rutgers.edu/login</li>
 * <li><code>renew</code> - true/false on whether to use renew or not.</li>
 * <li><code>gateway</code> - true/false on whether to use gateway or not.</li>
 * </ul>
 *
 * <p>Please see AbstractCasFilter for additional properties.</p>
 *
 * @author Scott Battaglia
 * @version $Revision: 11768 $ $Date: 2007-02-07 15:44:16 -0500 (Wed,07 Feb 2007) $
 * @since 3.0
 */
public class AuthenticationFilter extends AbstractCasFilter {
    /**
     * The URL to the CAS Server login.
     */
    private String casServerLoginUrl;
    /**
     * Whether to send the renew request or not.
     */
    private boolean renew = false;
    /**
     * Whether to send the gateway request or not.
     */
    private boolean gateway = false;
    
    private GatewayResolver gatewayStorage = new DefaultGatewayResolverImpl();
    protected void initInternal(final FilterConfig filterConfig) throws ServletException {
        if (!isIgnoreInitConfiguration()) {
            super.initInternal(filterConfig);
            setCasServerLoginUrl(getPropertyFromInitParams(filterConfig,"casServerLoginUrl",null));
            log.trace("Loaded CasServerLoginUrl parameter: " + this.casServerLoginUrl);
            setRenew(parseBoolean(getPropertyFromInitParams(filterConfig,"renew","false")));
            log.trace("Loaded renew parameter: " + this.renew);
            setGateway(parseBoolean(getPropertyFromInitParams(filterConfig,"gateway","false")));
            log.trace("Loaded gateway parameter: " + this.gateway);
            final String gatewayStorageClass = getPropertyFromInitParams(filterConfig,"gatewayStorageClass",null);
            if (gatewayStorageClass != null) {
                try {
                    this.gatewayStorage = (GatewayResolver) Class.forName(gatewayStorageClass).newInstance();
                } catch (final Exception e) {
                    log.error(e,e);
                    throw new ServletException(e);
                }
            }
        }
    }
    public void init() {
        super.init();
        CommonUtils.assertNotNull(this.casServerLoginUrl,"casServerLoginUrl cannot be null.");
    }
    public final void doFilter(final ServletRequest servletRequest,final ServletResponse servletResponse,final FilterChain filterChain) throws IOException,ServletException {
        final HttpServletRequest request = (HttpServletRequest) servletRequest;
        final HttpServletResponse response = (HttpServletResponse) servletResponse;
        final HttpSession session = request.getSession(false);
        final Assertion assertion = session != null ? (Assertion) session.getAttribute(CONST_CAS_ASSERTION) : null;
        if (assertion != null) {
            filterChain.doFilter(request,response);
            return;
        }
        final String serviceUrl = constructServiceUrl(request,response);
        final String ticket = CommonUtils.safeGetParameter(request,getArtifactParameterName());
        final boolean wasGatewayed = this.gatewayStorage.hasGatewayedAlready(request,serviceUrl);
        if (CommonUtils.isNotBlank(ticket) || wasGatewayed) {
            filterChain.doFilter(request,response);
            return;
        }
        final String modifiedServiceUrl;
        log.debug("no ticket and no assertion found");
        if (this.gateway) {
            log.debug("setting gateway attribute in session");
            modifiedServiceUrl = this.gatewayStorage.storeGatewayInformation(request,serviceUrl);
        } else {
            modifiedServiceUrl = serviceUrl;
        }
        if (log.isDebugEnabled()) {
            log.debug("Constructed service url: " + modifiedServiceUrl);
        }
        final String urlToRedirectTo = CommonUtils.constructRedirectUrl(this.casServerLoginUrl,getServiceParameterName(),modifiedServiceUrl,this.renew,this.gateway);
        if (log.isDebugEnabled()) {
            log.debug("redirecting to \"" + urlToRedirectTo + "\"");
        }
        response.sendRedirect(urlToRedirectTo);
    }
    public final void setRenew(final boolean renew) {
        this.renew = renew;
    }
    public final void setGateway(final boolean gateway) {
        this.gateway = gateway;
    }
    public final void setCasServerLoginUrl(final String casServerLoginUrl) {
        this.casServerLoginUrl = casServerLoginUrl;
    }
    
    public final void setGatewayStorage(final GatewayResolver gatewayStorage) {
    	this.gatewayStorage = gatewayStorage;
    }
}

看到104行可知，每次的请求都会判断session是否存在，如果session存在，则会继续接下来的请求，否则重定向到CAS服务端。既然如此，则可以在每次的ajax请求中带上;jsessionid=********；这样，就可以每次的请求都能获取到session。

那么问题来了，如何在每次的请求提交前，在url上获取文件上传服务器的sessionid的cookie呢？在这里我采用的是jsonp，在每次上传组件初始化之前，采用jsonp发送初始化请求，获取文件服务器上的sessionid，返回后绑定到请求的URL地址后。经测试，问题解决。

@Controller
public class InitController {
    @RequestMapping("init")
    @ResponseBody
    public String getId(HttpServletRequest req,HttpServletResponse res) {
        HttpSession session = req.getSession();
        res.setContentType("text/plain");
        String callbackFunName = req.getParameter("callbackparam");// 得到js函数名称
        String jsonp = "";
        if (session != null) {
            String id = session.getId();
            jsonp = "([ { jid:\"" + id + "\"}])";
        }
        return callbackFunName + jsonp;
    }
}
/* 初始化上传信息 */
function initConfig() {
	$.ajax({  
		url:prefix+'/init',data:'',async:false,dataType: "jsonp",jsonp: "callbackparam",//服务端用于接收callback调用的function名的参数   
		jsonpCallback: "success_jsonpCallback",//callback的function名称,服务端会把名称和data一起传递回来 
		success:function(result) {
			uploaderInit();
		},error:function(){
			alert("上传信息初始化失败!");
		},timeout:3000  
	}); 
}
function success_jsonpCallback(obj){
	if(obj.length>0&&obj[0].jid){
		var id = obj[0].jid;
		jid=';jsessionid='+id;
	}else{
		alert("上传信息初始化失败!");
	}
}

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原文链接：https://www.f2er.com/ajax/162856.html

CAS环境下的AJAX跨域

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