What is BeanNameViewResolver? - spring

Question

I read the documentation here, but I think that the Spring documentation is sometimes complex and hard to understand, so I need a little explanation about BeanNameViewResolver.
Can I get a code example?

Answer 1

As explained in the documentation,BeanNameViewResolver resolves Views declared as beans. Most of the time you need it for some special-purpose views.
For example, we need to render an Excel spreadsheet.
For the Excel generation you will Apache POI
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi</artifactId>
<version>3.6</version>
</dependency>
So, you subclass AbstractExcelView and implement your custom logic to render a spreadsheet based on model values.
public class CustomExcelView extends AbstractExcelView {
#Override
protected void buildExcelDocument(Map model, HSSFWorkbook workbook,
HttpServletRequest request, HttpServletResponse response)
throws Exception {
Map<String,String> revenueData = (Map<String,String>) model.get("revenueData");
//create a wordsheet
HSSFSheet sheet = workbook.createSheet("Revenue Report");
HSSFRow header = sheet.createRow(0);
header.createCell(0).setCellValue("Month");
header.createCell(1).setCellValue("Revenue");
int rowNum = 1;
for (Map.Entry<String, String> entry : revenueData.entrySet()) {
//create the row data
HSSFRow row = sheet.createRow(rowNum++);
row.createCell(0).setCellValue(entry.getKey());
row.createCell(1).setCellValue(entry.getValue());
}
}
}
and the controller simply adds the data
package com.example;
import java.util.HashMap;
import java.util.Map;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
#Controller
#RequestMapping("/excelview")
public class ExcelController {
public String getExcel(Model model){
Map<String,String> revenueData = new HashMap<String,String>();
revenueData.put("Jan-2010", "$100,000,000");
revenueData.put("Feb-2010", "$110,000,000");
revenueData.put("Mar-2010", "$130,000,000");
revenueData.put("Apr-2010", "$140,000,000");
revenueData.put("May-2010", "$200,000,000");
model.addAttribute("revenueData",revenueData);
return "myExcelView";
}
}
Then declaring an BeanNameViewResolver makes it available to controllers: when controller returns String with view name myExcelView, your spreadsheet will be rendered.
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-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.example" />
<bean class="org.springframework.web.servlet.view.BeanNameViewResolver" />
<bean id="myExcelView" class="com.example.CustomExcelView" />
</beans>