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08a. ⏯ Java Web App with Tomcat & Maven beginner video tutorial

Related Links 1. Getting started with Apache Tomcat application server by deploying a simple JEE Application. … Read more ›...

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08b. ⏯ Running Tomcat inside Eclipse beginner video tutorial

Related Links 1. Java Web App with Tomcat & Maven beginner video tutorial. 2. Getting started with Apache Tomcat application server by deploying a simple JEE Application. … Read more ›...

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09. SonarQube with Maven Tutorial – Code Quality for Java developers

Industry strength code needs to statically & dynamically capture code quality. Also, more and more organizations are using “production quality” home assignments to shortlist candidates for job interviews. So, it really pays to set up code quality tools like SonarQube on your home development environment to get feedback on your code quality with the view to learm &

…

09a: ⏯ JUnit with Mockito step by step video tutorial

Related Links 1. JUnit with Mockito step by step. … Read more ›...

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10: Getting started with MySQL database beginner tutorial

All Java developers not only must know “SQL”, but also a database is required for “JDBC tutorials”, “Hibernate Tutorials”, and so on. Any decent Java application will require a database. So, your self-taught Java projects must perform CRUD (i.e. Create Read, Update and Delete) operations on the database.

…

20+ Maven plugins listed for an enterprise Java (i.e. a JEE) project

In Maven, there are build and the reporting plugins. Build plugins will be executed during the build, and they should be configured in the “build” element.

What is a “Plugin Architecture”?

In this architecture, a core application defines an interface,

…

8+ JMeter performance testing interview Q&As

Performance testing is an important process of any software development. You can bring this up yourself to many open-ended questions like — Tell me about yourself? What are some of your recent accomplishments that you are proud of? Setting up a performance/load test script is always the first step in...

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Apache HTTPClient POST request sample code

This extends the Apache HTTPClient Tutorial to invoke RESTFul service with a POST request.

The 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.mytutorial</groupId>
    <artifactId>httpRestClient</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>httpRestClient</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>


        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
            <version>4.2.1</version>
        </dependency>

    </dependencies>
</project>

<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">

<groupId>com.mytutorial</groupId>

<artifactId>httpRestClient</artifactId>

<version>1.0-SNAPSHOT</version>

<name>httpRestClient</name>

<url>http://maven.apache.org</url>

<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

</properties>

<groupId>junit</groupId>

<artifactId>junit</artifactId>

</dependency>

<groupId>org.apache.httpcomponents</groupId>

<artifactId>httpclient</artifactId>

</dependency>

</dependencies>

</project>

The client using HttpClient & JAXBContext

The “JAXBContext” is from the Java 6 onwards. The sample code includes

1) Exception handling.

2) “BasicCredentialsProvider”

…

Apache HTTPClient Tutorial to invoke RESTFul service

Apache HttpClient to invoke a RESTful Web Service. This is a GET request, and in the next post will extend this to use an HTTP POST with basic authentication.

Step 1: Create a Maven project say “httpRestClient”. Just press enter for all the prompts.

…

Apache POI reading a xlsx file tutorial

Apache POI is a popular API that allows programmers to create, modify, and display MS Office files using Java programs. This tutorial shows how to read a xlsx file using Apache POI.

Difference between HSSF and XSSF?

HSSF is the POI Project’s pure Java implementation of the Excel ’97(-2007) file format.

…

Apache POI writing to a xlsx file tutorial

This extends the tutorial Apache POI reading an xlsx file tutorial.

Step 1: The “WriteToExcelFile” Java code.



package com.mytutorial;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class WriteToExcelFile {

    public static void main(String[] args) throws IOException {

        List<Employee> employees = new ArrayList<Employee>();
        employees.add(new Employee("P-123", "John", 24));
        employees.add(new Employee("C-456", "Peter", 36));

        // create work book and sheets
        XSSFWorkbook workBook = new XSSFWorkbook();
        XSSFSheet sheet = workBook.createSheet("simple sheet");

        // create rows and columns
        Row rowHeader = sheet.createRow(0);
        rowHeader.createCell(0).setCellValue("Employee NO");
        rowHeader.createCell(1).setCellValue("Employe Name");
        rowHeader.createCell(2).setCellValue("Employee Age");

        int rowNum = 1; // header is already created
        for (Employee emp : employees) {
            Row rowDetail = sheet.createRow(rowNum);
            rowDetail.createCell(0).setCellValue(emp.getId());
            rowDetail.createCell(1).setCellValue(emp.getName());
            rowDetail.createCell(2).setCellValue(emp.getAge());
            ++rowNum;
        }

        FileOutputStream fos = null;

        try {
            fos = new FileOutputStream(new File("C:\\temp\\employee-out.xlsx"));
            workBook.write(fos);
        }

        finally {
            fos.close();
        }

    }

    // to store data
    static class Employee {

        private String id;
        private String name;
        private int age;

        public Employee(String id, String name, int age) {
            this.id = id;
            this.name = name;
            this.age = age;
        }

        public String getId() {
            return id;
        }

        public void setId(String id) {
            this.id = id;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public int getAge() {
            return age;
        }

        public void setAge(int age) {
            this.age = age;
        }

        @Override
        public String toString() {
            return "Employee [id=" + id + ", name=" + name + ", age=" + age + "]";
        }
    }
}

package com.mytutorial;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.util.ArrayList;

import java.util.List;

import org.apache.poi.ss.usermodel.Row;

import org.apache.poi.xssf.usermodel.XSSFSheet;

import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class WriteToExcelFile {

public static void main(String[] args) throws IOException {

List<Employee> employees = new ArrayList<Employee>();

employees.add(new Employee("P-123", "John", 24));

employees.add(new Employee("C-456", "Peter", 36));

// create work book and sheets

XSSFWorkbook workBook = new XSSFWorkbook();

XSSFSheet sheet = workBook.createSheet("simple sheet");

// create rows and columns

Row rowHeader = sheet.createRow(0);

rowHeader.createCell(0).setCellValue("Employee NO");

rowHeader.createCell(1).setCellValue("Employe Name");

rowHeader.createCell(2).setCellValue("Employee Age");

int rowNum = 1; // header is already created

for (Employee emp : employees) {

Row rowDetail = sheet.createRow(rowNum);

rowDetail.createCell(0).setCellValue(emp.getId());

rowDetail.createCell(1).setCellValue(emp.getName());

rowDetail.createCell(2).setCellValue(emp.getAge());

++rowNum;

}

FileOutputStream fos = null;

try {

fos = new FileOutputStream(new File("C:\\temp\\employee-out.xlsx"));

workBook.write(fos);

}

finally {

fos.close();

}

// to store data

static class Employee {

private String id;

private String name;

private int age;

public Employee(String id, String name, int age) {

this.id = id;

this.name = name;

this.age = age;

}

public String getId() {

return id;

}

public void setId(String id) {

this.id = id;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public int getAge() {

return age;

}

public void setAge(int age) {

this.age = age;

}

@Override

public String toString() {

return "Employee [id=" + id + ", name=" + name + ", age=" + age + "]";

}

The xlsx file “employee-out.xlsx” will be created without any formatting.

Step 2: Adding styles

1) The columns are auto sized.

…

Apache POI writing to xlsx with styles

This extends the previous tutorial of Apache POI writing to an excel file by using a blank template employee-blank.xlsx file to be filled with data. The blank xlsx brings in the style and labels.

Step 1: employee-template.xlsx

Step 2: writing to xlsx file using poi

package com.mytutorial;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;

import org.apache.poi.ss.usermodel.BorderStyle;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CellStyle;
import org.apache.poi.ss.usermodel.Font;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.xssf.usermodel.XSSFCellStyle;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class WriteToExcelFile
{
    
    public static void main(String[] args) throws IOException
    {
        
        List<Employee> employees = new ArrayList<Employee>();
        employees.add(new Employee("P-123", "John", 24));
        employees.add(new Employee("C-456", "Peter", 36));
        
        InputStream is = Thread.currentThread().getContextClassLoader()
                .getResourceAsStream("com/mytutorial/employee-blank.xlsx");
        XSSFWorkbook workBook = new XSSFWorkbook(is);
        
        Sheet sheet = workBook.getSheet("Employees");
        
        //Font
        Font defaultFont = workBook.createFont();
        defaultFont.setFontHeightInPoints((short) 12);
        
        //Style
        XSSFCellStyle style = workBook.createCellStyle();
        style.setAlignment(CellStyle.ALIGN_CENTER);
        style.setBorderBottom(BorderStyle.THIN);
        style.setBorderLeft(BorderStyle.THIN);
        style.setBorderRight(BorderStyle.THIN);
        style.setBorderTop(BorderStyle.THIN);
        style.setWrapText(true);
        style.setFont(defaultFont);
        
        
        //cell values
        int rowNum = 1; // header is already created
        for (Employee emp : employees)
        {
            Row rowDetail = sheet.createRow(rowNum);
            Cell col1 = rowDetail.createCell(0);
            col1.setCellValue(emp.getId());
            col1.setCellStyle(style);
            
            Cell col2 = rowDetail.createCell(1);
            col2.setCellValue(emp.getName());
            col2.setCellStyle(style);
            
            Cell col3 = rowDetail.createCell(2);
            col3.setCellValue(emp.getAge());
            col3.setCellStyle(style);
            
            ++rowNum;
        }
        
        FileOutputStream fos = null;
        
        try
        {
            fos = new FileOutputStream(new File("C:\\temp\\employee-out.xlsx"));
            workBook.write(fos);
        }
        
        finally
        {
            fos.close();
            
        }
        
    }
    
    // to store data
    static class Employee
    {
        
        private String id;
        private String name;
        private int age;
        
        public Employee(String id, String name, int age)
        {
            this.id = id;
            this.name = name;
            this.age = age;
        }
        
        public String getId()
        {
            return id;
        }
        
        public void setId(String id)
        {
            this.id = id;
        }
        
        public String getName()
        {
            return name;
        }
        
        public void setName(String name)
        {
            this.name = name;
        }
        
        public int getAge()
        {
            return age;
        }
        
        public void setAge(int age)
        {
            this.age = age;
        }
        
        @Override
        public String toString()
        {
            return "Employee [id=" + id + ", name=" + name + ", age=" + age + "]";
        }   
    } 
}

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package com.mytutorial;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.util.ArrayList;

import java.util.List;

import org.apache.poi.ss.usermodel.BorderStyle;

import org.apache.poi.ss.usermodel.Cell;

import org.apache.poi.ss.usermodel.CellStyle;

import org.apache.poi.ss.usermodel.Font;

import org.apache.poi.ss.usermodel.Row;

import org.apache.poi.ss.usermodel.Sheet;

import org.apache.poi.xssf.usermodel.XSSFCellStyle;

import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class WriteToExcelFile

{

public static void main(String[] args) throws IOException

{

List<Employee> employees = new ArrayList<Employee>();

employees.add(new Employee("P-123", "John", 24));

employees.add(new Employee("C-456", "Peter", 36));

InputStream is = Thread.currentThread().getContextClassLoader()

.getResourceAsStream("com/mytutorial/employee-blank.xlsx");

XSSFWorkbook workBook = new XSSFWorkbook(is);

Sheet sheet = workBook.getSheet("Employees");

//Font

Font defaultFont = workBook.createFont();

defaultFont.setFontHeightInPoints((short) 12);

//Style

XSSFCellStyle style = workBook.createCellStyle();

style.setAlignment(CellStyle.ALIGN_CENTER);

style.setBorderBottom(BorderStyle.THIN);

style.setBorderLeft(BorderStyle.THIN);

style.setBorderRight(BorderStyle.THIN);

style.setBorderTop(BorderStyle.THIN);

style.setWrapText(true);

style.setFont(defaultFont);

//cell values

int rowNum = 1; // header is already created

for (Employee emp : employees)

{

Row rowDetail = sheet.createRow(rowNum);

Cell col1 = rowDetail.createCell(0);

col1.setCellValue(emp.getId());

col1.setCellStyle(style);

Cell col2 = rowDetail.createCell(1);

col2.setCellValue(emp.getName());

col2.setCellStyle(style);

Cell col3 = rowDetail.createCell(2);

col3.setCellValue(emp.getAge());

col3.setCellStyle(style);

++rowNum;

}

FileOutputStream fos = null;

try

{

fos = new FileOutputStream(new File("C:\\temp\\employee-out.xlsx"));

workBook.write(fos);

}

finally

{

fos.close();

}

// to store data

static class Employee

{

private String id;

private String name;

private int age;

public Employee(String id, String name, int age)

{

this.id = id;

this.name = name;

this.age = age;

}

public String getId()

{

return id;

}

public void setId(String id)

{

this.id = id;

}

public String getName()

{

return name;

}

public void setName(String name)

{

this.name = name;

}

public int getAge()

{

return age;

}

public void setAge(int age)

{

this.age = age;

}

@Override

public String toString()

{

return "Employee [id=" + id + ", name=" + name + ", age=" + age + "]";

}

Step 3: employee-out.xlsx

…

Auditing database tables Oracle tutorial

Triggers give you control just before data is changed and just after the data is changed. This allows for: 1) Auditing tables for changes like update, insert, and delete. 2) Data validation and column formatting before and after inserts into database. Q. … Read more ›...

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Blog Archives

08a. ⏯ Java Web App with Tomcat & Maven beginner video tutorial

08b. ⏯ Running Tomcat inside Eclipse beginner video tutorial

09. SonarQube with Maven Tutorial – Code Quality for Java developers

09a: ⏯ JUnit with Mockito step by step video tutorial

10: Getting started with MySQL database beginner tutorial

20+ Maven plugins listed for an enterprise Java (i.e. a JEE) project

8+ JMeter performance testing interview Q&As

Apache HTTPClient POST request sample code

Apache HTTPClient Tutorial to invoke RESTFul service

Apache POI reading a xlsx file tutorial

Apache POI writing to a xlsx file tutorial

Apache POI writing to xlsx with styles

Auditing database tables Oracle tutorial

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