In this tutorial we will build a simple Spring MVC 3 application with reporting capabilities. We will use Apache POI to generate dynamic Excel reports and Hibernate for the ORM framework. We will use a simple Java List as our data source. The data will be retrieved from a MySQL database.

This tutorial is part of the following reporting tutorial series that uses Jasper, DynamicJasper, and Apache POI:

Spring 3 - Apache POI - Hibernate: Creating an Excel Report Tutorial
Spring 3 - DynamicJasper - Hibernate Tutorial: Concatenating a DynamicReport
Spring 3 - DynamicJasper - Hibernate Tutorial: Concatenating a Subreport
Spring 3 - DynamicJasper - Hibernate Tutorial: Using Plain List
Spring 3 - DynamicJasper - Hibernate Tutorial: Using JRDataSource
Spring 3 - DynamicJasper - Hibernate Tutorial: Using HQL Query

All of these tutorials produce the same document, and all of them demonstrate different ways of creating the same report.

What is Apache POI?

The Apache POI Project's mission is to create and maintain Java APIs for manipulating various file formats based upon the Office Open XML standards (OOXML) and Microsoft's OLE 2 Compound Document format (OLE2). In short, you can read and write MS Excel files using Java. In addition, you can read and write MS Word and MS PowerPoint files using Java. Apache POI is your Java Excel solution (for Excel 97-2008).

Source: http://poi.apache.org/

Background

Before we start our application, let's preview first the final print document:

Our document is a simple Excel document. It's a Sales Report for a list of power supplies. The data is retrieved from a MySQL database.

Domain

Notice that for each Power Supply entry there's a common set of properties:

id
brand
model
maximum power
price
efficiency

Development

Domain

We'll start our application by declaring the domain object PowerSupply

PowerSupply.java

package org.krams.tutorial.domain;

import java.io.Serializable;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

/**
 * A simple POJO containing the common properties of a Power Supply
 * This is an annotated Hibernate entity. 
 * 
 * @author Krams at {@link http://krams915@blogspot.com}
 */
@Entity
@Table(name = "POWER_SUPPLY")
public class PowerSupply implements Serializable {

 private static final long serialVersionUID = 8634209606034270882L;

 @Id
 @Column(name = "ID")
 @GeneratedValue
 private Long id;
 
 @Column(name = "BRAND")
 private String brand;
 
 @Column(name = "MODEL")
 private String model;
 
 @Column(name = "MAXIMUM_POWER")
 private String maximumPower;
 
 @Column(name = "PRICE")
 private Double price;
 
 @Column(name = "EFFICIENCY")
 private Double efficiency;

 public Long getId() {
  return id;
 }

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

 public String getBrand() {
  return brand;
 }

 public void setBrand(String brand) {
  this.brand = brand;
 }

 public String getModel() {
  return model;
 }

 public void setModel(String model) {
  this.model = model;
 }

 public String getMaximumPower() {
  return maximumPower;
 }

 public void setMaximumPower(String maximumPower) {
  this.maximumPower = maximumPower;
 }

 public Double getPrice() {
  return price;
 }

 public void setPrice(Double price) {
  this.price = price;
 }

 public Double getEfficiency() {
  return efficiency;
 }

 public void setEfficiency(Double efficiency) {
  this.efficiency = efficiency;
 }
 
}

PowerSupply is a simple POJO containing six private fields. Each of these fields have been annotated with @Column and assigned with corresponding database column names.

ID
BRAND
MODEL
MAXIMUM_POWER
PRICE
EFFICIENCY

Service

We'll be declaring a single service named DownloadService. This service is the heart of the application that will process and retrieve the report document.

The service will run the following steps:

1. Create new workbook
2. Create new worksheet
3. Define starting indices for rows and columns
4. Build layout 
5. Fill report
6. Set the HttpServletResponse properties
7. Write to the output stream

DownloadService.java

package org.krams.tutorial.service;

import java.util.List;
import javax.servlet.http.HttpServletResponse;

import org.apache.log4j.Logger;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.krams.tutorial.domain.PowerSupply;
import org.krams.tutorial.report.FillManager;
import org.krams.tutorial.report.Layouter;
import org.krams.tutorial.report.Writer;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

/**
 * Service for processing Apache POI-based reports
 * 
 * @author Krams at {@link http://krams915@blogspot.com}
 */
@Service("downloadService")
@Transactional
public class DownloadService {

 private static Logger logger = Logger.getLogger("service");
 
 @Resource(name="sessionFactory")
 private SessionFactory sessionFactory;
 
 /**
  * Processes the download for Excel format.
  * It does the following steps:
  * <pre>1. Create new workbook
  * 2. Create new worksheet
  * 3. Define starting indices for rows and columns
  * 4. Build layout 
  * 5. Fill report
  * 6. Set the HttpServletResponse properties
  * 7. Write to the output stream
  * </pre>
  */
 @SuppressWarnings("unchecked")
 public void downloadXLS(HttpServletResponse response) throws ClassNotFoundException {
  logger.debug("Downloading Excel report");
  
  // 1. Create new workbook
  HSSFWorkbook workbook = new HSSFWorkbook();
  
  // 2. Create new worksheet
  HSSFSheet worksheet = workbook.createSheet("POI Worksheet");
  
  // 3. Define starting indices for rows and columns
  int startRowIndex = 0;
  int startColIndex = 0;
  
  // 4. Build layout 
  // Build title, date, and column headers
  Layouter.buildReport(worksheet, startRowIndex, startColIndex);

  // 5. Fill report
  FillManager.fillReport(worksheet, startRowIndex, startColIndex, getDatasource());
  
  // 6. Set the response properties
  String fileName = "SalesReport.xls";
  response.setHeader("Content-Disposition", "inline; filename=" + fileName);
  // Make sure to set the correct content type
  response.setContentType("application/vnd.ms-excel");
  
  //7. Write to the output stream
  Writer.write(response, worksheet);
 }
 
 /**
  * Retrieves the datasource as as simple Java List.
  * The datasource is retrieved from a Hibernate HQL query.
  */
 @SuppressWarnings("unchecked")
 private List<PowerSupply> getDatasource() {
  
      // Retrieve session
  Session session = sessionFactory.getCurrentSession();
  // Create query for retrieving products
  Query query = session.createQuery("FROM PowerSupply");
  // Execute query
  List<PowerSupply> result = query.list();
  
  // Return the datasource
  return result;
 }
}

This service is our download service for generating the report document. It should be clear what each line of code is doing.

The service has been divided into separate classes to encapsulate specific jobs.

The Layouter

The purpose of the Layouter is to layout the design of the report. Here's where we declare the dynamic columns and special properties of the document.

Layouter.java

package org.krams.tutorial.report;

import java.util.Date;
import org.apache.log4j.Logger;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.util.CellRangeAddress;
import org.apache.poi.hssf.util.HSSFColor;
import org.apache.poi.ss.usermodel.CellStyle;
import org.apache.poi.ss.usermodel.Font;

/**
 * Builds the report layout, the template, the design, the pattern or whatever synonym you may want to call it.
 * 
 * @author Krams at {@link http://krams915@blogspot.com}
 */
public class Layouter {

 private static Logger logger = Logger.getLogger("service");
 
 /**
  * Builds the report layout. 
  * <p>
  * This doesn't have any data yet. This is your template.
  */
 public static void buildReport(HSSFSheet worksheet, int startRowIndex, int startColIndex) {
  // Set column widths
  worksheet.setColumnWidth(0, 5000);
  worksheet.setColumnWidth(1, 5000);
  worksheet.setColumnWidth(2, 5000);
  worksheet.setColumnWidth(3, 5000);
  worksheet.setColumnWidth(4, 5000);
  worksheet.setColumnWidth(5, 5000);
  
  // Build the title and date headers
  buildTitle(worksheet, startRowIndex, startColIndex);
  // Build the column headers
  buildHeaders(worksheet, startRowIndex, startColIndex);
 }
 
 /**
  * Builds the report title and the date header
  * 
  * @param worksheet
  * @param startRowIndex starting row offset
  * @param startColIndex starting column offset
  */
 public static void buildTitle(HSSFSheet worksheet, int startRowIndex, int startColIndex) {
  // Create font style for the report title
  Font fontTitle = worksheet.getWorkbook().createFont();
  fontTitle.setBoldweight(Font.BOLDWEIGHT_BOLD);
  fontTitle.setFontHeight((short) 280);
  
        // Create cell style for the report title
        HSSFCellStyle cellStyleTitle = worksheet.getWorkbook().createCellStyle();
        cellStyleTitle.setAlignment(CellStyle.ALIGN_CENTER);
        cellStyleTitle.setWrapText(true);
        cellStyleTitle.setFont(fontTitle);
  
        // Create report title
  HSSFRow rowTitle = worksheet.createRow((short) startRowIndex);
  rowTitle.setHeight((short) 500);
  HSSFCell cellTitle = rowTitle.createCell(startColIndex);
  cellTitle.setCellValue("Sales Report");
  cellTitle.setCellStyle(cellStyleTitle);
  
  // Create merged region for the report title
  worksheet.addMergedRegion(new CellRangeAddress(0,0,0,5));
  
  // Create date header
  HSSFRow dateTitle = worksheet.createRow((short) startRowIndex +1);
  HSSFCell cellDate = dateTitle.createCell(startColIndex);
  cellDate.setCellValue("This report was generated at " + new Date());
 }
 
 /**
  * Builds the column headers
  * 
  * @param worksheet
  * @param startRowIndex starting row offset
  * @param startColIndex starting column offset
  */
 public static void buildHeaders(HSSFSheet worksheet, int startRowIndex, int startColIndex) {
  // Create font style for the headers
  Font font = worksheet.getWorkbook().createFont();
        font.setBoldweight(Font.BOLDWEIGHT_BOLD);

        // Create cell style for the headers
  HSSFCellStyle headerCellStyle = worksheet.getWorkbook().createCellStyle();
  headerCellStyle.setFillBackgroundColor(HSSFColor.GREY_25_PERCENT.index);
  headerCellStyle.setFillPattern(CellStyle.FINE_DOTS);
  headerCellStyle.setAlignment(CellStyle.ALIGN_CENTER);
  headerCellStyle.setVerticalAlignment(CellStyle.VERTICAL_CENTER);
  headerCellStyle.setWrapText(true);
  headerCellStyle.setFont(font);
  headerCellStyle.setBorderBottom(CellStyle.BORDER_THIN);
  
  // Create the column headers
  HSSFRow rowHeader = worksheet.createRow((short) startRowIndex +2);
  rowHeader.setHeight((short) 500);
  
  HSSFCell cell1 = rowHeader.createCell(startColIndex+0);
  cell1.setCellValue("Id");
  cell1.setCellStyle(headerCellStyle);

  HSSFCell cell2 = rowHeader.createCell(startColIndex+1);
  cell2.setCellValue("Brand");
  cell2.setCellStyle(headerCellStyle);

  HSSFCell cell3 = rowHeader.createCell(startColIndex+2);
  cell3.setCellValue("Model");
  cell3.setCellStyle(headerCellStyle);

  HSSFCell cell4 = rowHeader.createCell(startColIndex+3);
  cell4.setCellValue("Max Power");
  cell4.setCellStyle(headerCellStyle);

  HSSFCell cell5 = rowHeader.createCell(startColIndex+4);
  cell5.setCellValue("Price");
  cell5.setCellStyle(headerCellStyle);
 
  HSSFCell cell6 = rowHeader.createCell(startColIndex+5);
  cell6.setCellValue("Efficiency");
  cell6.setCellStyle(headerCellStyle);
 }
}

The FillManager

The purpose of the FillManager is to fill the Excel report with data from the data source.

FillManager.java

package org.krams.tutorial.report;

import java.util.List;

import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.ss.usermodel.CellStyle;
import org.krams.tutorial.domain.PowerSupply;

public class FillManager {

 /**
  * Fills the report with content
  * 
  * @param worksheet
  * @param startRowIndex starting row offset
  * @param startColIndex starting column offset
  * @param datasource the data source
  */
 public static void fillReport(HSSFSheet worksheet, int startRowIndex, int startColIndex, List<PowerSupply> datasource) {
  // Row offset
  startRowIndex += 2;
  
  // Create cell style for the body
  HSSFCellStyle bodyCellStyle = worksheet.getWorkbook().createCellStyle();
  bodyCellStyle.setAlignment(CellStyle.ALIGN_CENTER);
  bodyCellStyle.setWrapText(true);
  
  // Create body
  for (int i=startRowIndex; i+startRowIndex-2< datasource.size()+2; i++) {
   // Create a new row
   HSSFRow row = worksheet.createRow((short) i+1);

   // Retrieve the id value
   HSSFCell cell1 = row.createCell(startColIndex+0);
   cell1.setCellValue(datasource.get(i-2).getId());
   cell1.setCellStyle(bodyCellStyle);

   // Retrieve the brand value
   HSSFCell cell2 = row.createCell(startColIndex+1);
   cell2.setCellValue(datasource.get(i-2).getBrand());
   cell2.setCellStyle(bodyCellStyle);

   // Retrieve the model value
   HSSFCell cell3 = row.createCell(startColIndex+2);
   cell3.setCellValue(datasource.get(i-2).getModel());
   cell3.setCellStyle(bodyCellStyle);

   // Retrieve the maximum power value
   HSSFCell cell4 = row.createCell(startColIndex+3);
   cell4.setCellValue(datasource.get(i-2).getMaximumPower());
   cell4.setCellStyle(bodyCellStyle);

   // Retrieve the price value
   HSSFCell cell5 = row.createCell(startColIndex+4);
   cell5.setCellValue(datasource.get(i-2).getPrice());
   cell5.setCellStyle(bodyCellStyle);
  
   // Retrieve the efficiency value
   HSSFCell cell6 = row.createCell(startColIndex+5);
   cell6.setCellValue(datasource.get(i-2).getEfficiency());
   cell6.setCellStyle(bodyCellStyle);
  }
 }
}

The Writer

The purpose of the Writer is to write the "exported" worksheet to the output stream. Once the document has been written to the stream, the user will receive the document ready to be downloaded.

Writer.java

package org.krams.tutorial.report;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;

import org.apache.log4j.Logger;
import org.apache.poi.hssf.usermodel.HSSFSheet;

/**
 * Writes the report to the output stream
 * 
 * @author Krams at {@link http://krams915@blogspot.com}
 */
public class Writer {

 private static Logger logger = Logger.getLogger("service");
 /**
  * Writes the report to the output stream
  */
 public static void write(HttpServletResponse response, HSSFSheet worksheet) {
  
  logger.debug("Writing report to the stream");
  try {
   // Retrieve the output stream
   ServletOutputStream outputStream = response.getOutputStream();
   // Write to the output stream
   worksheet.getWorkbook().write(outputStream);
   // Flush the stream
   outputStream.flush();

  } catch (Exception e) {
   logger.error("Unable to write report to the output stream");
  }
 }
}

Controller

We've completed the domain and service layer of the application. Since we're developing a Spring MVC web application, we're required to declare a controller that will handle the user's request.

DownloadController.java

package org.krams.tutorial.controller;

import javax.annotation.Resource;
import javax.servlet.http.HttpServletResponse;
import org.apache.log4j.Logger;
import org.krams.tutorial.service.DownloadService;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

/**
 * Handles download requests
 * 
 * @author Krams at {@link http://krams915@blogspot.com}
 */
@Controller
@RequestMapping("/download")
public class DownloadController {

 private static Logger logger = Logger.getLogger("controller");
 
 @Resource(name="downloadService")
 private DownloadService downloadService;

 /**
  * Downloads the report as an Excel format. 
  * <p>
  * Make sure this method doesn't return any model. Otherwise, you'll get 
  * an "IllegalStateException: getOutputStream() has already been called for this response"
  */
    @RequestMapping(value = "/xls", method = RequestMethod.GET)
    public void getXLS(HttpServletResponse response, Model model) throws ClassNotFoundException {
     logger.debug("Received request to download report as an XLS");
     
     // Delegate to downloadService. Make sure to pass an instance of HttpServletResponse 
     downloadService.downloadXLS(response);
 }
}

DownloadController is a simple controller that handles download requests. It delegates report generation to the DownloadService. Notice we're required to pass the HttpServletResponse to the service.

Database Configuration

We've completed the MVC module of the application. However we haven't created yet the Hibernate configuration and the MySQL database.

Our first task is to create an empty MySQL database.

Here are the steps:
1. Run MySQL
2. Open MySQL admin
3. Create a new database mydb

In this tutorial I've setup a local MySQL database and used phpmyadmin to administer it.

Next, we'll be declaring a hibernate-context.xml configuration file. Its purpose is to contain all of Spring-related configuration for Hibernate.

hibernate-context.xml

This configuration requires two external configurations further:

spring.properties

# database properties
app.jdbc.driverClassName=com.mysql.jdbc.Driver
app.jdbc.url=jdbc:mysql://localhost/mydb
app.jdbc.username=root
app.jdbc.password=

#hibernate properties
hibernate.config=/WEB-INF/hibernate.cfg.xml

hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
  "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
  "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
  
<hibernate-configuration>
 <session-factory>
  <!-- We're using a MySQL database so the dialect needs to be MySQL as well -->
  <!-- Also we want to use MySQL's InnoDB engine -->
  <property name="hibernate.dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
  
  <!-- Enable this to see the Hibernate generated SQL statements in the logs -->
  <property name="show_sql">false</property>
  
  <!-- Setting this to 'create' will drop our existing database and re-create a new one.
    This is only good for testing. In production, this is a bad idea! -->
  <property name="hbm2ddl.auto">create</property>
 </session-factory>
</hibernate-configuration>

The Import.SQL

After declaring all the Hibernate-related configuration, let's now declare a SQL script that will populate our database with a sample data automatically.

import.sql

insert into POWER_SUPPLY (ID, BRAND, MODEL, MAXIMUM_POWER, PRICE, EFFICIENCY) values (null, 'Corsair', 'CMPSU-750TX', '750W', '109.99', '0.80')
insert into POWER_SUPPLY (ID, BRAND, MODEL, MAXIMUM_POWER, PRICE, EFFICIENCY) values (null, 'Antec', 'NEO ECO 620C', '620W', '69.99', '0.80')
insert into POWER_SUPPLY (ID, BRAND, MODEL, MAXIMUM_POWER, PRICE, EFFICIENCY) values (null, 'OCZ', 'OCZ700MXSP', '700W', '89.99', '0.86')
insert into POWER_SUPPLY (ID, BRAND, MODEL, MAXIMUM_POWER, PRICE, EFFICIENCY) values (null, 'Thermaltake', 'W0070RUC', '430W', '43.99', '0.65')
insert into POWER_SUPPLY (ID, BRAND, MODEL, MAXIMUM_POWER, PRICE, EFFICIENCY) values (null, 'COOLER MASTER', 'RS-460-PSAR-J3', '460W', '29.99', '0.70')
insert into POWER_SUPPLY (ID, BRAND, MODEL, MAXIMUM_POWER, PRICE, EFFICIENCY) values (null, 'Rosewill', 'RG530-S12', '530W', '54.99', '0.80')

Make sure to place this document under the classpath. Hibernate will automatically import the contents of this document everytime your start the application. This is dictated by the hbm2ddl.auto setting we declared in the hibernate.cfg.xml earlier.

We're not required to create this import.sql file. We could of course create a MySQL SQL script and import it directly to the database, or add the data manually in the database. I just believe this is convenient for development purposes.

Spring MVC Configuration

We've declared all the necessary classes and Hibernate-related configuration of the application. However, we haven't created yet the required Spring MVC configuration.

Let's begin with the web.xml
web.xml

<servlet>
  <servlet-name>spring</servlet-name>
  <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
  <load-on-startup>1</load-on-startup>
 </servlet>
 
 <servlet-mapping>
  <servlet-name>spring</servlet-name>
  <url-pattern>/krams/*</url-pattern>
 </servlet-mapping>

 <listener>
  <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
 </listener>

Take note of the URL pattern. When accessing any pages in our MVC application, the host name must be appended with

/krams

In the web.xml we declared a servlet-name spring. By convention, we must declare a spring-servlet.xml.

spring-servlet.xml

<!-- Declare a view resolver for resolving JSPs -->
 <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver" 
      p:prefix="/WEB-INF/jsp/" p:suffix=".jsp" />

By convention, we must declare an applicationContext.xml as well.

applicationContext.xml

<!-- Activates various annotations to be detected in bean classes -->
 <context:annotation-config />
 
 <!-- Scans the classpath for annotated components that will be auto-registered as Spring beans.
  For example @Controller and @Service. Make sure to set the correct base-package-->
 <context:component-scan base-package="org.krams.tutorial" />
 
 <!-- Configures the annotation-driven Spring MVC Controller programming model.
 Note that, with Spring 3.0, this tag works in Servlet MVC only!  -->
 <mvc:annotation-driven /> 
 
 <!-- Loads Hibernate related configuration -->
 <import resource="hibernate-context.xml" />

Run the Application

We've completed the application. Our last task is to run the application and download the report.

To run the application, open your browser and enter the following URL:

http://localhost:8080/spring-poi-hibernate/krams/download/xls

This will automatically download the report document. Again, here's the final screenshot of the document:

Conclusion

That's it. We've managed to build a simple Spring MVC 3 application with reporting capabilities. We used Apache POI to generate the dynamic Excel reports and Hibernate for the ORM framework. Lastly, we used a plain Java List as the data source where the data is retrieved from a MySQL database.

Download the project
You can access the project site at Google's Project Hosting at http://code.google.com/p/spring-poi-integration-tutorial/

You can download the project as a Maven build. Look for the spring-poi-hibernate.zip in the Download sections.

You can run the project directly using an embedded server via Maven.
For Tomcat: mvn tomcat:run
For Jetty: mvn jetty:run

If you want to learn more about Spring MVC and integration with other technologies, feel free to read my other tutorials in the Tutorials section.

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