Read & Construct CSV File Using Java Code

http://agiletribe.wordpress.com/2012/11/23/the-only-class-you-need-for-csv-files

Input CSV File

package com.pritom.kumar;

import java.io.*;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;

/**
 * Created by pritom on 10/10/2014.
 */
public class ReadCsvFile {
    final static Charset ENCODING = StandardCharsets.UTF_8;
    private Integer maxRowSize = 0;
    List dataList = new ArrayList();
    public String DELIMITER = ",";

    public static void main(String[] args) throws Exception {
        ReadCsvFile readCsvFile = new ReadCsvFile();
        Long started = System.currentTimeMillis();
        readCsvFile.run();
        Long finished = System.currentTimeMillis();
        Long timeTaken = finished - started;
        readCsvFile.prettyPrint();
        readCsvFile.println("Time Taken: " + timeTaken + " Milli Seconds.");
        readCsvFile.println(readCsvFile.toHtml("csv-output.html"));
        readCsvFile.println(readCsvFile.toCsv("csv-output.csv"));
        System.exit(200);
    }

    public String toCsv(String fileName) throws Exception {
        File file = new File(fileName);
        List fileLines = new ArrayList();
        for (Object object : dataList) {
            fileLines.add(listToBuffer((List) object).toString());
        }
        writeStringList(fileLines, file.getAbsolutePath());
        return file.getAbsolutePath();
    }

    private StringBuffer listToBuffer(List data) {
        StringBuffer stringBuffer = new StringBuffer();
        Boolean firstValue = true;
        for (Object value : data) {
            String line = value.toString();
            if (!firstValue) {
                stringBuffer.append(DELIMITER);
            }
            stringBuffer.append("\"");
            for (Integer index = 0; index < line.length(); index++) {
                char chars = line.charAt(index);
                if (chars == '\"') {
                    stringBuffer.append("\"");
                }
                stringBuffer.append(chars);
            }
            stringBuffer.append("\"");
            firstValue = false;
        }
        return stringBuffer;
    }

    public String toHtml(String fileName) throws Exception {
        File file = new File(fileName);
        List fileLines = new ArrayList();
        for (Integer dataIndex = 0; dataIndex < dataList.size(); dataIndex++) {
            List columnData = (ArrayList) dataList.get(dataIndex);
            maxRowSize = columnData.size() > maxRowSize ? columnData.size() : maxRowSize;
        }
        StringBuffer stringBuffer = new StringBuffer();
        stringBuffer.append("<table>");
        for (Integer dataIndex = 0; dataIndex < dataList.size(); dataIndex++) {
            List columnData = (ArrayList) dataList.get(dataIndex);
            stringBuffer.append("<tr><td>" + (dataIndex + 1) + "</td>");
            for (Integer headerIndex = 0; headerIndex < maxRowSize; headerIndex++) {
                stringBuffer.append("<td style='border: 1px solid black;'>" +(columnData.size() > headerIndex ? columnData.get(headerIndex) : "") + "&nbsp;</td>");
            }
            stringBuffer.append("</tr>\n");
            if (dataIndex % 10 == 0) {
                fileLines.add(stringBuffer.toString());
                stringBuffer = new StringBuffer();
            }
        }
        stringBuffer.append("</table>");
        fileLines.add(stringBuffer.toString());
        writeStringList(fileLines, file.getAbsolutePath());
        return file.getAbsolutePath();
    }

    public Boolean writeStringList(List<String> aLines, String aFileName) throws IOException {
        try {
            Path path = Paths.get(aFileName);
            Files.write(path, aLines, ENCODING);
            return true;
        }
        catch (Exception ex) {
            ex.printStackTrace();
            return false;
        }
    }

    public void prettyPrint() {
        for (Integer dataIndex = 0; dataIndex < dataList.size(); dataIndex++) {
            List columnData = (ArrayList) dataList.get(dataIndex);
            print((dataIndex + 1) + ": ");
            for (Integer headerIndex = 0; headerIndex < columnData.size(); headerIndex++) {
                print("<" + columnData.get(headerIndex) + ">");
                if (headerIndex + 1 < columnData.size()) {
                    print(", ");
                }
            }
            println("");
        }
    }

    public void run() throws Exception {
        String csvFile = "input.csv";
        BufferedReader br = null;
        FileReader fileReader = new FileReader(csvFile);
        String line = "";
        try {
            br = new BufferedReader(fileReader);
            while ((line = br.readLine()) != null) {
                if (line.trim().length() > 0) {
                    List tempDataList = parseLine(line.trim());
                    maxRowSize = tempDataList.size() > maxRowSize ? tempDataList.size() : maxRowSize;
                    dataList.add(tempDataList);
                }
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (fileReader != null) {
                try {
                    fileReader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    private List parseLine(String string) throws Exception{
        InputStream stream = new ByteArrayInputStream(string.getBytes("UTF-8"));
        Reader fr = new InputStreamReader(stream, "UTF-8");
        int chars = fr.read();
        while (chars == '\r') {
            chars = fr.read();
        }
        if (chars < 0) {
            return new ArrayList();
        }
        List dataList = new ArrayList();
        StringBuffer stringBuffer = new StringBuffer();
        Boolean inQuotes = false, lineStarted = false;
        while (chars > 0) {
            if (inQuotes) {
                lineStarted = true;
                if (chars == '\"') {
                    inQuotes = false;
                }
                else {
                    stringBuffer.append((char) chars);
                }
            }
            else {
                if (chars == '\"') {
                    inQuotes = true;
                    if (lineStarted) {
                        stringBuffer.append('\"');
                    }
                }
                else if (chars == DELIMITER.charAt(0)) {
                    dataList.add(stringBuffer.toString());
                    stringBuffer = new StringBuffer();
                    lineStarted = false;
                }
                else if (chars == '\r') {

                }
                else if (chars == '\n') {
                    break;
                }
                else {
                    stringBuffer.append((char) chars);
                }
            }
            chars = fr.read();
        }
        dataList.add(stringBuffer.toString());
        return dataList;
    }

    private void print(Object object) {
        System.out.print(object);
    }

    private void println(Object object) {
        System.out.println(object);
    }
}

Output would be like this:

1: <permalink>, <company>, <numEmps>, <category>, <city>, <state>, <fundedDate>, <raisedAmt>, <raisedCurrency>, <round>
2: <lifelock>, <LifeLock Limited,Company">, <>, <web>, <Tempe>, <AZ>, <1-May-07>, <6850000>, <USD>, <b>
....................
1459: <myrio>, <Myrio>, <75>, <software>, <Bothell>, <WA>, <1-Jan-01>, <20500000>, <USD>, <unattributed>
1460: <grid-networks>, <Grid Networks>, <>, <web>, <Seattle>, <WA>, <30-Oct-07>, <9500000>, <USD>, <a>
1461: <grid-networks>, <Grid Networks>, <>, <web>, <Seattle>, <WA>, <20-May-08>, <10500000>, <USD>, <b>
Time Taken: 96 Milli Seconds.
C:\codes\javap\csv-output.html
C:\codes\javap\csv-output.csv

Java Code for Calculating HMAC-SHA1 & HMAC-SHA256 Signature

package com.pritom.kumar;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

/**
 * Created by pritom on 09/10/2014.
 */
public class HmacSha1 {
    public static void main(String[] args) {
        System.out.println(hmacSha1("mykey", "helloworld"));
        System.out.println(hmacSha256("mykey", "helloworld"));
    }

    public static String hmacSha1(String KEY, String VALUE) {
        return hmacSha(KEY, VALUE, "HmacSHA1");
    }

    public static String hmacSha256(String KEY, String VALUE) {
        return hmacSha(KEY, VALUE, "HmacSHA256");
    }

    private static String hmacSha(String KEY, String VALUE, String SHA_TYPE) {
        try {
            SecretKeySpec signingKey = new SecretKeySpec(KEY.getBytes("UTF-8"), SHA_TYPE);
            Mac mac = Mac.getInstance(SHA_TYPE);
            mac.init(signingKey);
            byte[] rawHmac = mac.doFinal(VALUE.getBytes("UTF-8"));

            byte[] hexArray = {
                    (byte)'0', (byte)'1', (byte)'2', (byte)'3',
                    (byte)'4', (byte)'5', (byte)'6', (byte)'7',
                    (byte)'8', (byte)'9', (byte)'a', (byte)'b',
                    (byte)'c', (byte)'d', (byte)'e', (byte)'f'
            };
            byte[] hexChars = new byte[rawHmac.length * 2];
            for ( int j = 0; j < rawHmac.length; j++ ) {
                int v = rawHmac[j] & 0xFF;
                hexChars[j * 2] = hexArray[v >>> 4];
                hexChars[j * 2 + 1] = hexArray[v & 0x0F];
            }
            return new String(hexChars);
        }
        catch (Exception ex) {
            throw new RuntimeException(ex);
        }
    }
}

Output would be like this:

74ae5a4a3d9996d5918defc2c3d475471bbf59ac
7fdfaa9c9c0931f52d9ebf2538bc99700f2e771f3af1c1d93945c2256c11aedd

GRAILS Render Or Display XML In Browser

import groovy.xml.XmlUtil
....
def xmlString = "YOUR XML STRING";
def xmlAsText = XmlUtil.serialize(xmlString)
render(text: xmlAsText, encoding:"UTF-8", contentType:"text/xml")

GRAILS Custom Codec Example

All custom codec must be in grails-app/utils folder in any package.
Suppose I first created a package named 'pritom.kumar.codecs'.
Then created a groovy (not other type of class) class inside the package such named 'UpperCodec'.groovy
Class name must be end with 'Codec'.
My custom codec groovy class look like this:

package pritom.kumar.codecs

/**
 * Created by pritom on 05/09/2014.
 */
class UpperCodec {
    static encode = { target ->
        return target != null && target instanceof String ? target.toString().toUpperCase() : target
    }
}

Now you can use this as code in controller, service, other java or groovy classes, views and other places like this.

println "i am pritom kumar".encodeAsUpper();

Will print the following:

I AM PRITOM KUMAR

Basically you can do various things using custom codec.

Spring MVC - Custom Exception Handling & Send Appropriate Error Code

Download full source code

Create a custom exception handler class as follows:

package com.pkm.maven.exception;

public class SpringException extends RuntimeException {
    private String exceptionMsg;
    
    public SpringException(String exceptionMsg) {
        this.exceptionMsg = exceptionMsg;
    }
    
    public String getExceptionMsg() {
        return this.exceptionMsg;
    }
    
    public void setExceptionMsg(String exceptionMsg) {
        this.exceptionMsg = exceptionMsg;
    }
}

Add following lines of code to your XXX-servlet.xml under WEB-INF

<bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
    <property name="exceptionMappings">
        <props>
            <prop key="com.pkm.maven.exception.SpringException">ExceptionPage</prop>
        </props>
    </property>
    <property name="defaultErrorView" value="error"/>
</bean>

Create a jsp page named 'ExceptionPage.jsp' defined in previous XXX-servlet.xml file under WEB-INF folder.

<h3 class="error">${exception.exceptionMsg}</h3>

Also create a file named 'error.jsp' under WEB-INF/jsp/ folder

<h3>General Error Page</h3>

Now time to throw custom exception

From method1 & method2 i am throwing my custom error so rendering my custom error page 'ErrorPage.jsp' & in method4, I am not throwing any exception but when invoking the line 'nullString.length()', it automatically throwing general exception, so rendering 'error.jsp' as defined in XXX-servlet.xml.

package com.pkm.maven.controller;

import com.pkm.maven.exception.SpringException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.multiaction.MultiActionController;

/**
 * Controller action would be like this
 * public (ModelAndView | Map | String | void) actionName(HttpServletRequest, HttpServletResponse [,HttpSession] [,CommandObject]);
 * @author Pritom K Mondal
 */

public class CustomerController extends MultiActionController {    
    public ModelAndView method1(HttpServletRequest request, HttpServletResponse response) throws Exception { 
        response.setStatus( HttpServletResponse.SC_BAD_REQUEST  );
        throw new SpringException("Error from customer controller and method1() action.");
        //return new ModelAndView("CustomerPage", "msg", "method1() method"); 
    }
 
    public ModelAndView method2(HttpServletRequest request, HttpServletResponse response) throws Exception { 
        response.setStatus( HttpServletResponse.SC_BAD_REQUEST  );
        throw new Exception("Error from customer controller and method2() action.");
        //return new ModelAndView("CustomerPage", "msg", "method2() method"); 
    }
 
    public ModelAndView method3(HttpServletRequest request, HttpServletResponse response) throws Exception { 
        return new ModelAndView("CustomerPage", "msg", "method3() method"); 
    }
 
    public ModelAndView method4(HttpServletRequest request, HttpServletResponse response) throws Exception { 
        String nullString = null;
        Integer length = nullString.length();
        return new ModelAndView("CustomerPage", "msg", "method4() method"); 
    }
}

Output would be like this in browser if you browse 'customer/method1' or 'customer/method2':

Output would be like this in browser if you browse 'customer/method4':

Access Spring-ApplicationContext/ServletContext From Everywhere

Create a java class such named 'AppUtils.java' with following contents:

package com.pkm.maven.common;

import javax.servlet.ServletContext;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

public class AppUtils implements ApplicationContextAware {
    private static ApplicationContext ctx;
    private static ServletContext __servletContext;
    
    @Override
    public void setApplicationContext(ApplicationContext ctx) {
        AppUtils.ctx = ctx;
    }
    
    public static ApplicationContext getApplicationContext() {
        return ctx;
    }
    
    public static ServletContext getServletContext() {
        if (__servletContext == null) {
            __servletContext = (ServletContext) ctx.getBean("servletContext");
        }
        return __servletContext;
    }
}

Now make a entry to 'applicationContext.xml'

<bean id="contextApplicationContextProvider" class="com.pkm.maven.common.AppUtils"></bean>

Finally access application context/servlet context from everywhere like this:

package com.pkm.maven.app;

import com.pkm.maven.common.AppUtils;
import javax.servlet.ServletContext;
import org.springframework.context.ApplicationContext;

public class AppHandler {
    
    public static String getContextPath() {
        try {
            ApplicationContext applicationContext = AppUtils.getApplicationContext();
            ServletContext servletContext = AppUtils.getServletContext();
            return servletContext.getContextPath();
        }
        catch (Exception ex) {
            return "<b>ERROR</b>";
        }
    }
}

Spring MVC with ControllerClassNameHandlerMapping MultiActionController

maven2-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:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
       http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
       http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd
       http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd">

    <context:component-scan base-package="com.pkm.maven"/>
    <bean class="org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping">
        <property name="caseSensitive" value="true" />
        <!--<property name="pathPrefix" value="/pathPrefix" />-->
    </bean>
    <bean class="com.pkm.maven.controller.CustomerController"/>

    <bean id="viewResolver"
    	class="org.springframework.web.servlet.view.InternalResourceViewResolver" >
        <property name="prefix">
            <value>/WEB-INF/jsp/</value>
        </property>
        <property name="suffix">
            <value>.jsp</value>
        </property>
        <property name="viewClass">
            <value>com.pkm.maven.common.JstlView</value>
        </property>
    </bean>
</beans>

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">
    <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>maven2</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>maven2</servlet-name>
        <url-pattern>*.htm</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>
</web-app>

CustomerController.java

package com.pkm.maven.controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.multiaction.MultiActionController;
 
public class CustomerController extends MultiActionController{
 
    public ModelAndView method1(HttpServletRequest request, HttpServletResponse response) throws Exception { 
        return new ModelAndView("CustomerPage", "msg", "method1() method"); 
    }
 
    public ModelAndView method2(HttpServletRequest request, HttpServletResponse response) throws Exception { 
        return new ModelAndView("CustomerPage", "msg", "method2() method"); 
    }
}

You have to create a file named 'CustomerPage.jsp' under WEB-INF/jsp/

URL would be like this

• customer/method1.htm
• customer/method2.htm

Download example src code