DiyTomcat系列教材（六十四）- Filter 的配置

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步骤 1 : 拓扑图点亮
步骤 2 : javaweb 配置 Filter
步骤 3 : PfmFilter
步骤 4 : URLFilter
步骤 5 : web.xml
步骤 6 : 比较可运行项目，快速定位问题

步骤 1 :

拓扑图点亮

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自己写一个Tomcat，几乎使用到了除开框架外的所有Java 技术，如多线程，Socket, J2EE, 反射，Log4j, JSoup, JUnit, Html 等一整套技术栈，从无到有，循序渐进涵盖全部74个知识点，549个开发步骤, 为竞争高薪资职位加上一个有吸引力的砝码.
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步骤 2 :

javaweb 配置 Filter

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步骤 3 :

PfmFilter

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代码行数较多，请点击查看

package cn.how2j.javaweb;

import java.io.IOException;
import java.util.Enumeration;

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;

public class PfmFilter implements Filter{

	@Override
	public void destroy() {
		
	}

	@Override
	public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
			throws IOException, ServletException {
		
		HttpServletRequest request =  (HttpServletRequest) servletRequest;
		
		String url = request.getRequestURL().toString();
		
		long start = System.currentTimeMillis();
		filterChain.doFilter(servletRequest, servletResponse);
		long end = System.currentTimeMillis();
		System.out.println((end-start) + " ms elapsed on url:" +url);
	}

	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
		System.out.println("PrmFilter 的初始化参数：");
		Enumeration<String>  e = filterConfig.getInitParameterNames();
		while(e.hasMoreElements()){
			String name = e.nextElement();
			String value = filterConfig.getInitParameter(name);
			System.out.println("name:" + name);
			System.out.println("value:" + value);
		}
	}

}

步骤 4 :

URLFilter

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代码行数较多，请点击查看

package cn.how2j.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;

public class URLFilter implements Filter{

	@Override
	public void destroy() {
		System.out.println("URLFilter 的 destroy() 被调用");
	}
	
	@Override
	public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
			throws IOException, ServletException {
		
		HttpServletRequest request =  (HttpServletRequest) servletRequest;
		String url = request.getRequestURL().toString();
		System.out.println("url filter:" + url);
		filterChain.doFilter(servletRequest, servletResponse);
	}

	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
		
	}

}

步骤 5 :

web.xml

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<?xml version="1.0" encoding="UTF-8"?> <web-app> <servlet> <servlet-name>HelloServlet</servlet-name> <servlet-class>cn.how2j.javaweb.HelloServlet</servlet-class> <init-param> <param-name>author</param-name> <param-value>how2j(servlet)</param-value> </init-param> <init-param> <param-name>site</param-name> <param-value>http://how2j.cn(servlet)</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>HelloServlet</servlet-name> <url-pattern>/hello</url-pattern> </servlet-mapping> <servlet> <servlet-name>ParamServlet</servlet-name> <servlet-class>cn.how2j.javaweb.ParamServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>ParamServlet</servlet-name> <url-pattern>/param</url-pattern> </servlet-mapping> <servlet> <servlet-name>HeaderServlet</servlet-name> <servlet-class>cn.how2j.javaweb.HeaderServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>HeaderServlet</servlet-name> <url-pattern>/header</url-pattern> </servlet-mapping> <servlet> <servlet-name>SetCookieServlet</servlet-name> <servlet-class>cn.how2j.javaweb.SetCookieServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>SetCookieServlet</servlet-name> <url-pattern>/setCookie</url-pattern> </servlet-mapping> <servlet> <servlet-name>GetCookieServlet</servlet-name> <servlet-class>cn.how2j.javaweb.GetCookieServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>GetCookieServlet</servlet-name> <url-pattern>/getCookie</url-pattern> </servlet-mapping> <servlet> <servlet-name>SetSessionServlet</servlet-name> <servlet-class>cn.how2j.javaweb.SetSessionServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>SetSessionServlet</servlet-name> <url-pattern>/setSession</url-pattern> </servlet-mapping> <servlet> <servlet-name>GetSessionServlet</servlet-name> <servlet-class>cn.how2j.javaweb.GetSessionServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>GetSessionServlet</servlet-name> <url-pattern>/getSession</url-pattern> </servlet-mapping> <servlet> <servlet-name>ClientJumpServlet</servlet-name> <servlet-class>cn.how2j.javaweb.ClientJumpServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>ClientJumpServlet</servlet-name> <url-pattern>/jump1</url-pattern> </servlet-mapping> <servlet> <servlet-name>ServerJumpServlet</servlet-name> <servlet-class>cn.how2j.javaweb.ServerJumpServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>ServerJumpServlet</servlet-name> <url-pattern>/jump2</url-pattern> </servlet-mapping> <filter> <filter-name>URLFilter</filter-name> <filter-class>cn.how2j.javaweb.URLFilter</filter-class> </filter> <filter-mapping> <filter-name>URLFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <filter> <filter-name>PfmFilter</filter-name> <filter-class>cn.how2j.javaweb.PfmFilter</filter-class> <init-param> <param-name>author</param-name> <param-value>how2j(filter)</param-value> </init-param> <init-param> <param-name>site</param-name> <param-value>http://how2j.cn(filter)</param-value> </init-param> </filter> <filter-mapping> <filter-name>PfmFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> </web-app>

代码行数较多，请点击查看

<?xml version="1.0" encoding="UTF-8"?>
<web-app>
    <servlet>
        <servlet-name>HelloServlet</servlet-name>
        <servlet-class>cn.how2j.javaweb.HelloServlet</servlet-class>
        <init-param>
            <param-name>author</param-name>
            <param-value>how2j(servlet)</param-value>
        </init-param>
        <init-param>
            <param-name>site</param-name>
            <param-value>http://how2j.cn(servlet)</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>HelloServlet</servlet-name>
        <url-pattern>/hello</url-pattern>
    </servlet-mapping>

    <servlet>
        <servlet-name>ParamServlet</servlet-name>
        <servlet-class>cn.how2j.javaweb.ParamServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>ParamServlet</servlet-name>
        <url-pattern>/param</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>HeaderServlet</servlet-name>
        <servlet-class>cn.how2j.javaweb.HeaderServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>HeaderServlet</servlet-name>
        <url-pattern>/header</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>SetCookieServlet</servlet-name>
        <servlet-class>cn.how2j.javaweb.SetCookieServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>SetCookieServlet</servlet-name>
        <url-pattern>/setCookie</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>GetCookieServlet</servlet-name>
        <servlet-class>cn.how2j.javaweb.GetCookieServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>GetCookieServlet</servlet-name>
        <url-pattern>/getCookie</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>SetSessionServlet</servlet-name>
        <servlet-class>cn.how2j.javaweb.SetSessionServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>SetSessionServlet</servlet-name>
        <url-pattern>/setSession</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>GetSessionServlet</servlet-name>
        <servlet-class>cn.how2j.javaweb.GetSessionServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>GetSessionServlet</servlet-name>
        <url-pattern>/getSession</url-pattern>
    </servlet-mapping>

    <servlet>
        <servlet-name>ClientJumpServlet</servlet-name>
        <servlet-class>cn.how2j.javaweb.ClientJumpServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>ClientJumpServlet</servlet-name>
        <url-pattern>/jump1</url-pattern>
    </servlet-mapping>

    <servlet>
        <servlet-name>ServerJumpServlet</servlet-name>
        <servlet-class>cn.how2j.javaweb.ServerJumpServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>ServerJumpServlet</servlet-name>
        <url-pattern>/jump2</url-pattern>
    </servlet-mapping>

    <filter>
        <filter-name>URLFilter</filter-name>
        <filter-class>cn.how2j.javaweb.URLFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>URLFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <filter>
        <filter-name>PfmFilter</filter-name>
        <filter-class>cn.how2j.javaweb.PfmFilter</filter-class>
        <init-param>
            <param-name>author</param-name>
            <param-value>how2j(filter)</param-value>
        </init-param>
        <init-param>
            <param-name>site</param-name>
            <param-value>http://how2j.cn(filter)</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>PfmFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

</web-app>

步骤 6 :

比较可运行项目，快速定位问题

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使用爬虫已经被系统记录，请勿使用爬虫，增大封号风险。如果是误封，请联系站长，谢谢

DiyTomcat系列教材（六十三）- 责任链模式

DiyTomcat系列教材（六十五）- Filter 的加载和初始化

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