一、 获取此次请求的URL

String requestUrl = request.getScheme() //当前链接使用的协议

+"://" + request.getServerName()//服务器地址

+ ":" + request.getServerPort() //端口号

+ request.getContextPath() //应用名称，如果应用名称为

+ request.getServletPath() //请求的相对url

+ "?" + request.getQueryString(); //请求参数

举例：

http://127.0.0.1:8080/world/index.jsp?name=lilei&sex=1

request.getScheme() = "http";

request.getServerName() = "127.0.0.1";

request.getServerPort() = "8080";

request.getContextPath() = "world";

request.getServletPath() = "index.jsp";

request.getQueryString() = "name=lilei&sex=1";

http://127.0.0.1:8080/world/index.jsp?name=lilei&sex=1

request.getScheme() = "http";

request.getServerName() = "127.0.0.1";

request.getServerPort() = "8080";

request.getContextPath() = "";

request.getServletPath() = "world/index.jsp";

request.getQueryString() = "name=lilei&sex=1";

二、获取服务器根路径

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

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使用如下：