MVC in Eclipse.
Introduction
Let's make a sample program of MVC in Eclipse.
Development environment
Windows 10 Pro 1709(16299.192) Eclipse pleiades-4.7.3 java 1.8.0_162
procedure
-
- Install Eclipse Pleiades All in One I want to use it in other languages later, so I will install the full version. "Ultimate": Can be developed in other than Java (C / C ++, Python ...) "Full Edition": Includes compiler and execution environment
-
Creating a dynamic web project
-
- "Hello World" in Servlet
-
"Employee list display" in MVC M (Model): JavaBeans (Java class) V（View） : JSP C (Controller): Servlet (Java class)
1. 1. Install Eclipse Pleiades All in One
URL
http://mergedoc.osdn.jp/
Installation procedure
1. Click "Eclipse 4.7 Oxygen"
2. Change the mirror server (because it may time out in 3.)
3. Click "Ultimate" "Full Edition" of Windws 64bit
4. Unzip the download file into your working folder
2. Creating a dynamic web project
Start Eclipse
1. Double-click "eclipse.exe"
2. Click the "Start" button
- If you do not want to display this dialog at the next startup, check "Select this ..."
New project generation
3. Select "File"-> "New"-> "Other" menu
4. Select "Dynamic Web Project" and click the "Next" button.
5. Enter the "Project Name", select "Tomcat8", and click the "Next" button.
6. Click the "Next" button
7. Check "Generate web.xml Deployment Descriptor" and click "Finish" button.
3. 3. "Hello World" in Servlet
1) Create Servlet
1. Select "File"-> "New"-> "Other" menu
2. Select "Jakarta" and click the "Next" button.
3. Enter the "Java Package" and "Class Name" and click the "Finish" button.
4. Open the created Servlet class and add one line
response.getWriter().append("\nHello World !!");
2) Operation check
1. Select the "Run"-> "Run"-> "Run on Server" menu
2. Select "Tomcat 8.0 server", check "Always use this server when running this project", and click the "Finish" button.
3. Enter the URL on your browser
http://localhost:8080/SampleMVC/ShowHelloWorld
4. Check the definition of the URL path (http: // localhost / SampleMVC / ShowHelloWorld)
SampleMVC :The project name is defined in the Tomcat configuration file when selecting the server to use
ShowHelloWorld :URL mapping when creating a Servlet Java file,@WebServlet("/ShowHelloWorld")Defined as
4. "Employee list display" in MVC
0) JSTL download
1. Download taglibs-standard-impl-1.2.5.jar, taglibs-standard-jstlel-1.2.5.jar, taglibs-standard-spec-1.2.5.jar
http://tomcat.apache.org/download-taglibs.cgi
2. Copy to WEB-INF \ lib of the project
1) Model (JavaBeans) creation
1. Select "File"-> "New"-> "Class" menu
2. Enter the "Java Package" and "Class Name" and click the "Finish" button.
3. Code creation
package emp;
public class EmployeeBean {
private String id = "";
private String name = "";
private String email = "";
public void setId(String id){
this.id = id;
}
public String getId(){
return this.id;
}
public void setName(String name){
this.name = name;
}
public String getName(){
return this.name;
}
public void setEmail(String email){
this.email = email;
}
public String getEmail(){
return this.email;
}
}
2) Create Servlet (Controller)
1. Select "File"-> "New"-> "Other" menu
2. Select "Jakarta" and click the "Next" button.
3. Enter the "Java Package" and "Class Name" and click the "Next" button.
4. Set the Servlet deployment identifier name, check the URL mapping, and click the "Finish" button.
5. Code generation
package emp;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class EmployeeServlet
*/
@WebServlet(name = "EmpList", urlPatterns = { "/EmpList" })
public class EmployeeServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public EmployeeServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//Model generation
List<EmployeeBean> employeeList = new ArrayList<EmployeeBean>();
EmployeeBean bean = new EmployeeBean();
bean.setId("00001");
bean.setName("Hayako Sato");
bean.setEmail("[email protected]");
employeeList.add(bean);
bean = new EmployeeBean();
bean.setId("00002");
bean.setName("Taro Suzuki");
bean.setEmail("[email protected]");
employeeList.add(bean);
bean = new EmployeeBean();
bean.setId("00003");
bean.setName("Ryo Ikeda");
bean.setEmail("[email protected]");
employeeList.add(bean);
//Pass Model to View
request.setAttribute("employeeList", employeeList);
//Show View
this.getServletContext()
.getRequestDispatcher("/employeeList.jsp")
.forward(request, response);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//Model generation
Map<String, EmployeeBean> employeeMap = new HashMap<String, EmployeeBean>();
EmployeeBean bean = new EmployeeBean();
bean.setId("00001");
bean.setName("Hayako Sato");
bean.setEmail("[email protected]");
employeeMap.put(bean.getId(), bean);
bean = new EmployeeBean();
bean.setId("00002");
bean.setName("Taro Suzuki");
bean.setEmail("[email protected]");
employeeMap.put(bean.getId(), bean);
bean = new EmployeeBean();
bean.setId("00003");
bean.setName("Ryo Ikeda");
bean.setEmail("[email protected]");
employeeMap.put(bean.getId(), bean);
String id = request.getParameter("id");
List<EmployeeBean> employeeList = new ArrayList<EmployeeBean>();
if (id.isEmpty()) {
for (Map.Entry<String, EmployeeBean> entry : employeeMap.entrySet()) {
employeeList.add(entry.getValue());
}
}
else {
employeeList.add(employeeMap.get(id));
}
//Pass Model to View
request.setAttribute("employeeList", employeeList);
//Show View
this.getServletContext()
.getRequestDispatcher("/employeeList.jsp")
.forward(request, response);
}
}
3) View (JSP) creation
1. Select "File"-> "New"-> "Other" menu
2. Select "JSP File" and click the "Next" button.
4. Enter the "Folder" and "File name" and click the "Finish" button.
5. Code generation
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Employee list</title>
</head>
<body>
<form action="EmpList" method="post">
<p>
ID：<input type="text" name="id">
</p>
<p>
<input type="submit" value="Send">
<input type="reset" value="Reset your input">
</p>
</form>
<table>
<caption>
<strong>Employee list</strong>
</caption>
<thead>
<tr>
<th>ID</th>
<th>NAME</th>
<th>EMAIL</th>
</tr>
</thead>
<tbody>
<c:forEach items="${employeeList}" var="emp" >
<tr>
<th><c:out value="${emp.id}" /></th>
<td><c:out value="${emp.name}" /></td>
<td><c:out value="${emp.email}" /></td>
</tr>
</c:forEach>
</tbody>
</table>
</body>
</html>
4) Operation check
1. Select the "Run"-> "Run"-> "Run on Server" menu
2. Enter the URL on your browser
http://localhost:8080/SampleMVC/EmpList
3. You can search by ID
4. If no ID is entered, all items will be displayed.
in conclusion
--EmployeeBean accessors (setXxx (), getXxx ()) can be omitted using lombok.
--When you enter the URL ( http: // localhost: 8080 / SampleMVC / EmpList), call the EmployeeServlet.doGet () method.
--When you click the "Send" button, call the EmployeeServlet.doPost () method.
--The HashMap class cannot retrieve elements in the order they were put. You can use LinkedHashMap to retrieve them in the order they were inserted.
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