util

Logging HTTP Request Parameters using HTTP Servlet

By edwin / 6 April 2014 13 June 2014 / Java, Programming / Java, servlet, util, utility, web

This is a servlet filter that i use if i want to log what parameters fired by my REST client, basically it’s just a simple http servlet filter.

package com.edw;

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;
import org.apache.log4j.Logger;

public class LoggingFilter implements Filter {

    private Logger logger = Logger.getLogger(this.getClass());
    
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        
        try {
            HttpServletRequest req = (HttpServletRequest) request;
            
            String uri = req.getRequestURI();
            logger.debug("Requested Resource::"+uri);
            
            Enumeration<String> enumeration = req.getParameterNames();
            
            while(enumeration.hasMoreElements()) {
                String parametername = enumeration.nextElement();
                logger.debug(parametername + " : " +req.getParameter(parametername));
            }
        } catch (Exception e) {
            logger.error(e,e);
        }
        
        chain.doFilter(request, response);
    }

    @Override
    public void destroy() {
    }
}

Add your servlet filer to your web.xml and listen for a specific url request, on this example i listen for requests to /services/ url.

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">    
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    
    <filter>
	<filter-name>LogFilter</filter-name>
	<filter-class>
		com.edw.LoggingFilter
	</filter-class>
    </filter>
    <filter-mapping>
            <filter-name>LogFilter</filter-name>
            <url-pattern>/services/*</url-pattern>
    </filter-mapping>    
</web-app>

Create and Exporting A Web-Based Excel Report Using JXLS and SpringMVC

By edwin / 31 March 2014 31 March 2014 / Java, Programming / Java, report, util, utility, web

Today im trying to create a simple excel exporter report using SpringMVC. Im integrating JXLS library with SpringMVC framework. I prefer using JXLS compared to JasperReport or other java-to-excel-library due to its easy templating, so i dont need to create excel formatting from java code.

I start with my 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>com.edw</groupId>
    <artifactId>JXLSSpringMVC</artifactId>
    <version>1.0</version>
    <packaging>war</packaging>

    <name>JXLSSpringMVC</name>

    <properties>
        <endorsed.dir>${project.build.directory}/endorsed</endorsed.dir>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>javax</groupId>
            <artifactId>javaee-web-api</artifactId>
            <version>6.0</version>
            <scope>provided</scope>
        </dependency>
        
        <!-- Spring 3 dependencies -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>3.1.1.RELEASE</version>
        </dependency> 
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>3.1.1.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>3.1.1.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>3.1.1.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>3.1.1.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>cglib</groupId>
            <artifactId>cglib</artifactId>
            <version>2.2</version>
        </dependency>
        <dependency>
            <groupId>commons-codec</groupId>
            <artifactId>commons-codec</artifactId>
            <version>1.9</version>
        </dependency>
        
        <!-- jxls -->
        <dependency>
            <groupId>net.sf.jxls</groupId>
            <artifactId>jxls-core</artifactId>
            <version>0.9.9</version>
        </dependency>
        
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.3.2</version>
                <configuration>
                    <source>1.6</source>
                    <target>1.6</target>
                    <compilerArguments>
                        <endorseddirs>${endorsed.dir}</endorseddirs>
                    </compilerArguments>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>2.1.1</version>
                <configuration>
                    <failOnMissingWebXml>false</failOnMissingWebXml>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-dependency-plugin</artifactId>
                <version>2.1</version>
                <executions>
                    <execution>
                        <phase>validate</phase>
                        <goals>
                            <goal>copy</goal>
                        </goals>
                        <configuration>
                            <outputDirectory>${endorsed.dir}</outputDirectory>
                            <silent>true</silent>
                            <artifactItems>
                                <artifactItem>
                                    <groupId>javax</groupId>
                                    <artifactId>javaee-endorsed-api</artifactId>
                                    <version>6.0</version>
                                    <type>jar</type>
                                </artifactItem>
                            </artifactItems>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

And a simple web.xml file

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/applicationContext.xml</param-value>
    </context-param>
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>2</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
</web-app>

And 2 SpringMVC configuration file, applicationContext.xml,

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.0.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd">

    <context:annotation-config/>
    
    <tx:annotation-driven/>
    
    <context:component-scan base-package="com.edw.jxlsspringmvc"/>
    
</beans>

and dispatcher-servlet.xml,

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <context:component-scan base-package="com.edw.jxlsspringmvc.controller" />
	
    <mvc:annotation-driven />

    <bean id="viewResolver"
          class="org.springframework.web.servlet.view.InternalResourceViewResolver"
          p:prefix="/WEB-INF/jsp/"
          p:suffix=".jsp" />
</beans>

And a simple excel file,

A java controller file,

package com.edw.jxlsspringmvc.controller;

import java.io.FileInputStream;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.ServletContext;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import net.sf.jxls.transformer.XLSTransformer;
import org.apache.poi.ss.usermodel.Workbook;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

/**
 *
 * @author edwin < edwinkun at gmail dot com >
 */
@Controller
public class IndexController {

    @Autowired
    private ServletContext context;
    
    @RequestMapping(value = "/", method = RequestMethod.GET)
    public String index() {
        return "index";
    }
    
    @RequestMapping(value = "/export", method = RequestMethod.GET)
    public String export(HttpServletRequest request, HttpServletResponse response) {
        try {
            // set output header
            ServletOutputStream os = response.getOutputStream();
            response.setContentType("application/vnd.ms-excel");
            response.setHeader("Content-Disposition", "attachment; filename=\"myexcel.xls\"");
            
            String reportLocation = context.getRealPath("WEB-INF");

            Map beans = new HashMap();
            beans.put("name", "Edwin");
            beans.put("address", "Jakarta, Indonesia");
            XLSTransformer transformer = new XLSTransformer();

            Workbook workbook = transformer.transformXLS(new FileInputStream(reportLocation + "/myexcel.xls"), beans);
            workbook.write(os);
            os.flush();

            return null;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }    
}

And my index.jsp file

<html>
    <head>
        <title>Download Excel</title>
    </head>
    <body>
        <a href="${pageContext.request.contextPath}/export">download excel</a>
    </body>
</html>

My Netbeans project structure is like this,

And this is the result when im clicking on the website’s download url,

Have fun with JXLS 🙂

How to Inserting 0 To an AutoIncreament Field on MySql

By edwin / 6 January 2014 6 January 2014 / Database, Programming / database, mysql, util, utility

Let say i have this table,

CREATE TABLE `refproductscale` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `scale` varchar(255) NOT NULL,
  `del` set('y','n') NOT NULL DEFAULT 'n',
  PRIMARY KEY (`id`)
)

I dont know why, but everytime im inserting ‘zero’ as its id, suddenly it changes into an increament number.
But with this script, im able to insert ‘zero’ as its id. This is my script,

SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO";
insert into refproductscale values(0, 'none', 'n');

And this is the result,

All i have to do is use NO_AUTO_VALUE_ON_ZERO before i do insert query. 😉

How to Setup HTTPS Connection for NginX

By edwin / 4 January 2014 4 January 2014 / nix, Programming / Programming, util, utility, webserver

I just bought a new SSL Certificate from an SSL providers, and now im trying to install it on my nginx webserver. Now im trying to share the steps needed to install my ssl certificate, in case someone need it.

But first, i need to generate a .key and .csr file using openssl’s command, i will need those files to become a “secret key” or my private key.

sudo openssl req -new -newkey rsa:2048 -nodes -keyout domain.key -out domain.csr

Next is i send my .csr file to SSL providers to generate .crt files. In my case, the SSL Provider, gives me 2 .crt files. First is the “Intermediate Certificate” (my_intermediate_ca.crt) and another one is “SSL Certificate” files (domain.crt).

First, i need to join those 2 crt files,

cat domain.crt my_intermediate_ca.crt >> bundle.crt

It will look like this,

-----BEGIN CERTIFICATE-----
..... my domain.crt .......
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
..... my intermediate.crt .......
-----END CERTIFICATE-----

Next is registering my SSL on nginx, i just edit the ssl.conf here

sudo vi /etc/nginx/conf.d/ssl.conf

and add this lines

server {
    listen       443 default ssl;
    server_name  mydomain;

    server_tokens off;

    ssl_certificate      /crtlocation/bundle.crt;
    ssl_certificate_key  /crtlocation/domain.key;

    ssl_session_cache shared:SSL:1m;
    ssl_session_timeout  5m;

    ssl_ciphers  HIGH:!aNULL:!MD5;
    ssl_prefer_server_ciphers   on;

    location / {
        root   /usr/share/nginx/html;
        index  index.html index.htm;
	}
}

Restart nginx and check your ssl using openssl command,

openssl s_client -debug -connect localhost:443

A good SSL configuration will give this result,

Verify return code: 0 (ok)

While bad ones will create result like this,

Hope it would help others, have fun 😀

ps.
i had one weird condition on my previous ssl installation, somehow my website shows valid ssl on desktop browsers, but shows broken ssl when accessed from mobile devices and android browsers. I found out it’s due to i provide the wrong .crt file on nginx’s ssl.conf, i provide domain.crt instead of bundle.crt. 🙁

How to Create A Simple Captcha Using Java Servlet

By edwin / 11 October 2013 11 October 2013 / Java, Programming / Programming, servlet, util, web

On this article im going to create a simple image captcha that will show a 5-random alphanumeric letters, im using SimpleCaptha library to help me creating images and validating user’s input.

First is a simple java servlet, it will build random images and store its value on httpsession.

package com.edw.captcha;

import java.awt.Color;
import java.awt.Font;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import nl.captcha.Captcha;
import nl.captcha.backgrounds.GradiatedBackgroundProducer;
import nl.captcha.servlet.CaptchaServletUtil;
import nl.captcha.text.renderer.DefaultWordRenderer;

public class EdwCaptcha extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        List<Color> colors = new ArrayList<Color> ();
        colors.add(Color.black);
        colors.add(Color.red);
        
        List<Font> fonts = new ArrayList<Font>();
        fonts.add(new Font("Arial", Font.ITALIC, 40));
        
        Captcha captcha = new Captcha.Builder(120, 50)
                .addText(new DefaultWordRenderer(colors, fonts))
                .addBackground(new GradiatedBackgroundProducer(Color.white, Color.white))
                .gimp()
                .addBorder()
                .build();

        // display the image produced
        CaptchaServletUtil.writeImage(response, captcha.getImage());

        // save the captcha value on session
        request.getSession().setAttribute("simpleCaptcha", captcha); 
    }
}

And now im registering my servlet on my web.xml,

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    
    <servlet>
        <servlet-name>Captcha</servlet-name>
        <servlet-class>com.edw.captcha.EdwCaptcha</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Captcha</servlet-name>
        <url-pattern>/Captcha.jpg</url-pattern>
    </servlet-mapping>    
</web-app>

Here is the result image generated from my servlet,

You can validate the submitted captcha values by comparing it with the values that you store in httpsession.