JavaWeb（HttpServletRequestWrapper）

大鹏一日同风起，扶摇直上九万里。这篇文章主要讲述JavaWeb：HttpServletRequestWrapper相关的知识，希望能为你提供帮助。
环境

JDK 8
Spring Tool Suite 4.6.1
Servlet 3.1
Tomcat 8.5
Maven 3.6.3

概述在 Servlet API 中有四个包装类，它们的作用类似，这里以 HttpServletRequestWrapper 为例学习。
四个包装类分别是：

ServletRequestWrapper
HttpServletRequestWrapper
ServletResponseWrapper
HttpServletResponseWrapper

HttpServletRequestWrapper 说明HttpServletRequestWrapper 主要是 HttpServletRequest 的包装，
它提供了 HttpServletRequest 的所有方法，主要作用是改变 HttpServletRequest 的行为。
HttpServletRequestWrapper 示例 pom.xml

< project xmlns=" http://maven.apache.org/POM/4.0.0" xmlns:xsi=" http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation=" http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" > < modelVersion> 4.0.0< /modelVersion> < groupId> jiangbo.javaweb< /groupId> < artifactId> 17java-web-http-servlet-request-wrapper< /artifactId> < version> 1.0.0< /version> < packaging> war< /packaging> < description> Http Servlet Request Wrapper 的示例< /description> < properties> < maven.compiler.source> 1.8< /maven.compiler.source> < maven.compiler.target> 1.8< /maven.compiler.target> < project.build.sourceEncoding> UTF-8< /project.build.sourceEncoding> < /properties> < dependencies> < dependency> < groupId> javax.servlet< /groupId> < artifactId> javax.servlet-api< /artifactId> < version> 3.1.0< /version> < scope> provided< /scope> < /dependency> < /dependencies> < /project>

Servlet01

package jiangbo.javaweb; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @SuppressWarnings(" serial" ) public class Servlet01 extends HttpServlet {@Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {System.out.println(" service..." ); System.out.println(" name: " + req.getParameter(" name" )); } }

Filter01

package jiangbo.javaweb; 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.HttpServletRequestWrapper; public class Filter01 implements Filter {@Override public void init(FilterConfig filterConfig) throws ServletException { }@Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { chain.doFilter(new KeyWordWrapper(request), response); }@Override public void destroy() { }static class KeyWordWrapper extends HttpServletRequestWrapper {private static final String KEY_WORD = " java" ; public KeyWordWrapper(ServletRequest request) { super((HttpServletRequest) request); }@Override public String getParameter(String name) { return super.getParameter(name).replaceAll(KEY_WORD, " ****" ); } } }

配置 web.xml

< web-app xmlns=" http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi=" http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation=" http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" version=" 3.1" > < servlet> < servlet-name> servlet01< /servlet-name> < servlet-class> jiangbo.javaweb.Servlet01< /servlet-class> < /servlet> < servlet-mapping> < servlet-name> servlet01< /servlet-name> < url-pattern> /servlet01< /url-pattern> < /servlet-mapping> < filter> < filter-name> filter01< /filter-name> < filter-class> jiangbo.javaweb.Filter01< /filter-class> < /filter> < filter-mapping> < filter-name> filter01< /filter-name> < servlet-name> servlet01< /servlet-name> < /filter-mapping> < /web-app>

浏览器访问
【JavaWeb（HttpServletRequestWrapper）】将该项目部署到服务器并启动，在客户端访问 http://localhost:8080/17java-web-http-servlet-request-wrapper/servlet01?name=javascript 项目地址，然后关闭 tomcat。
控制台输出