Servlet Filter Response Pre Post

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package com.cv.servlet.filter.response; import java.io.CharArrayWriter; import java.io.PrintWriter; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpServletResponseWrapper; import org.apache.log4j.Logger; /**  * Servlet Filter implementation class CharResponseWrapper  *   * @author Chandra Vardhan  *   */ public class CharResponseWrapper extends HttpServletResponseWrapper {   private static final Logger LOGGER = Logger       .getLogger(CharResponseWrapper.class);   private CharArrayWriter output;   public String toString() {     LOGGER.info("LOGGER : CharResponseWrapper toString()");     return output.toString();   }   public CharResponseWrapper(HttpServletResponse response) {     super(response);     output = new CharArrayWriter();     LOGGER.info("LOGGER : CharResponseWrapper CharResponseWrapper(HttpServletResponse)");   }   public PrintWriter getWriter() {     LOGGER.info("LOGGER : CharResponseWrapper getWriter()");        return new PrintWriter(output);        } }

package com.cv.servlet.filter.response; import java.io.IOException; import java.io.OutputStream; import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.http.HttpServletResponse; import org.apache.log4j.Logger; /**  * Servlet Filter implementation class PrePostFilter  *   * @author Chandra Vardhan  *   */ public class PrePostFilter implements Filter {   private static final Logger LOGGER = Logger       .getLogger(PrePostFilter.class);   private ServletContext context;   public void init(FilterConfig fConfig) throws ServletException {     LOGGER.info("init ... ResponseChangeFilter");     this.context = fConfig.getServletContext();     this.context.log("ResponseChangeFilter initialized");   }   public void doFilter(ServletRequest request, ServletResponse response,       FilterChain chain) throws IOException, ServletException {     LOGGER.info("doFilter ... ResponseChangeFilter BEFORE filter");     OutputStream out = response.getOutputStream();     out.write("<HR>PRE<HR>".getBytes());     CharResponseWrapper wrapper = new CharResponseWrapper(         (HttpServletResponse) response);     chain.doFilter(request, wrapper);     out.write(wrapper.toString().getBytes());     out.write("<HR>POST<HR>".getBytes());     out.close();   }   public void destroy() {     // we can close resources here     LOGGER.info("destroy ... RequestParameterChangeFilter");   } }

package com.cv.servlet.filter.response; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.log4j.Logger; /**  * Servlet Filter implementation class TestServlet  *   * @author Chandra Vardhan  *   */ public class TestServlet extends HttpServlet {   private static final Logger LOGGER = Logger       .getLogger(PrePostFilter.class);   private static final long serialVersionUID = 1L;   /**    * @see HttpServlet#HttpServlet()    */   public TestServlet() {     super();   }   /**    * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse    *      response)    */   protected void doGet(HttpServletRequest request,       HttpServletResponse response) throws ServletException, IOException {     LOGGER.info("LOGGER : TestServlet doGet(HttpServletRequest,HttpServletResponse)");     LOGGER.info("LOGGER : Provided output Test chandra vardhan kodam");     response.getWriter().print("Test chandra vardhan kodam");   }   /**    * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse    *      response)    */   protected void doPost(HttpServletRequest request,       HttpServletResponse response) throws ServletException, IOException {     LOGGER.info("LOGGER : TestServlet doPost(HttpServletRequest ,HttpServletResponse )");     doGet(request, response);   } }

<!DOCTYPE html> <html> <head> <meta charset="ISO-8859-1"> <title>Insert title here</title> </head> <body> <br> <br> <a href="TestServlet">Click here to get response...</a> </body> </html>

#By default enabling Console appender # Root logger option log4j.rootLogger=INFO, stdout # Redirect log messages to console log4j.appender.stdout=org.apache.log4j.ConsoleAppender log4j.appender.stdout.Target=System.out log4j.appender.stdout.layout=org.apache.log4j.PatternLayout log4j.appender.stdout.layout.ConversionPattern=%-5p [%c]:%L -->> %m%n # Redirect log messages to a log file #log4j.appender.file=org.apache.log4j.RollingFileAppender #log4j.appender.file.File=C:\\servlet-application.log #log4j.appender.file.MaxFileSize=5MB #log4j.appender.file.MaxBackupIndex=10 #log4j.appender.file.layout=org.apache.log4j.PatternLayout #log4j.appender.file.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

<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> <artifactId>ServletFilterResponsePrePost</artifactId> <version>1.0</version> <packaging>war</packaging> <properties> <log4j.version>1.2.16</log4j.version> <java.version>1.8</java.version> </properties> <build> <plugins> <plugin> <artifactId>maven-compiler-plugin</artifactId> <version>3.3</version> <configuration> <source>${java.version}</source> <target>${java.version}</target> </configuration> </plugin> <plugin> <artifactId>maven-war-plugin</artifactId> <version>2.6</version> <configuration> <warSourceDirectory>WebContent</warSourceDirectory> <failOnMissingWebXml>false</failOnMissingWebXml> </configuration> </plugin> </plugins> </build> <dependencies> <dependency> <groupId>javax.servlet</groupId> <artifactId>servlet-api</artifactId> <version>3.0-alpha-1</version> </dependency> <dependency> <groupId>commons-fileupload</groupId> <artifactId>commons-fileupload</artifactId> <version>1.3.1</version> </dependency> <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>${log4j.version}</version> </dependency> <dependency> <groupId>javax.servlet.jsp</groupId> <artifactId>jsp-api</artifactId> <version>2.0</version> </dependency> <dependency> <groupId>jstl</groupId> <artifactId>jstl</artifactId> <version>1.2</version> </dependency> <dependency> <groupId>taglibs</groupId> <artifactId>standard</artifactId> <version>1.1.2</version> </dependency> </dependencies> <groupId>com.cv.servlet.filter.response</groupId> </project>

<?xml version="1.0" encoding="UTF-8"?> <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>TestServlet</servlet-name> <servlet-class>com.cv.servlet.filter.response.TestServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>TestServlet</servlet-name> <url-pattern>/TestServlet</url-pattern> </servlet-mapping> <filter> <filter-name>PrePostFilter</filter-name> <filter-class>com.cv.servlet.filter.response.PrePostFilter</filter-class> </filter> <filter-mapping> <filter-name>PrePostFilter</filter-name> <url-pattern>/TestServlet</url-pattern> </filter-mapping> <welcome-file-list> <welcome-file>index.html</welcome-file> </welcome-file-list> </web-app>