web.xml配置過濾器

在web.xml中定義一個isCross初始化變數，用於開啟是否允許跨域訪問。這將很好的控制跨域訪問問題。

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app id="WebApp_ID">
    <display-name>TestCrossOrigin</display-name
 
>

    <filter>
        <filter-name>CrossOriginControl</filter-name>
        <filter-class>test.cross.origin.CrossOriginControl</filter-class>
        <init-param>
            <param-name>IsCross</param-name>
            <param-value>true</param-value
 
>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>CrossOriginControl</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <servlet>
        <servlet-name>crossOrigin</servlet-name>
        <servlet-class
 
>test.cross.origin.CrossOriginTestServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>crossOrigin</servlet-name>
        <url-pattern>/crossOrigin</url-pattern>
    </servlet-mapping>

    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.htm</welcome-file>
        <welcome-file>index.jsp</welcome-file>
        <welcome-file>default.html</welcome-file>
        <welcome-file>default.htm</welcome-file>
        <welcome-file>default.jsp</welcome-file>
    </welcome-file-list>
</web-app>

filter[CrossOriginControl]實現

package test.cross.origin;

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.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class CrossOriginControl implements Filter{
    private boolean isCross = false;

    @Override
    public void destroy() {
        // TODO Auto-generated method stub
        isCross = false;
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        // TODO Auto-generated method stub
        if(isCross){
            HttpServletRequest httpServletRequest = (HttpServletRequest)request;
            HttpServletResponse httpServletResponse = (HttpServletResponse)response;
            System.out.println("攔截請求: "+httpServletRequest.getServletPath());
            httpServletResponse.setHeader("Access-Control-Allow-Origin", "*");  
            httpServletResponse.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");  
            httpServletResponse.setHeader("Access-Control-Max-Age", "0");  
            httpServletResponse.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");  
            httpServletResponse.setHeader("Access-Control-Allow-Credentials", "true");  
            httpServletResponse.setHeader("XDomainRequestAllowed","1");  
        }
        chain.doFilter(request, response);
    }

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        // TODO Auto-generated method stub
        String isCrossStr = filterConfig.getInitParameter("IsCross");
        isCross = isCrossStr.equals("true")?true:false;
        System.out.println(isCrossStr);
    }

}

測試servlet[CrossOriginTestServlet]

package test.cross.origin;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class CrossOriginTestServlet extends HttpServlet{

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        PrintWriter writer = resp.getWriter();
        writer.write("cross success");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
        super.doGet(req, resp);
    }

}

結果測試

當isCross為false時：

當isCross為true時：