Reprinted: Link to this article: http://blog.csdn.net/u013621398/article/details/108563928
Contact list operation effect
demand analysis
The essence is to query a List collection, and then forward the request to the page, and use the el expression to add a jstl tag to display it.
Write business logic
We are test-driven development, so we first write the test logic, then implement the logic and add the page
test\java\com\wzx\service\TestContactService.java
public class TestContactService {
@Test
public void test01(){
//1:创建业务类对象
ContactService contactService = new ContactService();
//2:调用查询
List<Contact> contactList = contactService.queryAll();
//3:遍历
for(Contact contact:contactList){
System.out.println(contact);
}
}
}
Writing entity classes
The
essence of src\com\wzx\bean\Contact.java is to model the data
//联系人实体类
public class Contact {
private int id;
private String name;
private String sex;
private int age;
private String address;
private String qq;
private String email;
Write business class
src\com\wzx\service\ContactService.java
//service层
public class ContactService {
//1:创建数据层访问对象
private ContactDao dao = new ContactDao();
public List<Contact> queryAll() {
//2:调用全查方法
return dao.findAll();
}
}
Write the data access layer
src\com\wzx\dao\ContactDao.java
currently does not integrate jdbc and mysql, because this section focuses on the three-tier architecture, as long as you highlight the three-tier
//数据访问层
public class ContactDao {
public List<Contact> findAll() {
//创建集合
List<Contact> list = new ArrayList<>();
for (int i = 0; i < 10; i++) {
//添加元素
Contact contact = new Contact(i,"name"+i,"男",10,"bj","QQ","[email protected]");
list.add(contact);
}
return list;
}
}
At this point, you can run a test test, as long as there is no problem with the data, it is relatively easy to increase the page display
Add page servlet
src\com\wzx\web\ContactListServlet.java
@WebServlet("/list")
public class ContactListServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request,response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1:创建业务类对象
ContactService contactService = new ContactService();
//2:调用查询
List<Contact> contactList = contactService.queryAll();
//3:遍历打印，改成请求转发，并且使用el与jstl来展示
request.setAttribute("list",contactList);
request.getRequestDispatcher("/list.jsp").forward(request,response);
}
}
Add page el and jstl
Add the jar of jstl
Create a new page to import tags and traverse data
web\list.jsp
<%@page import="com.wzx.bean.Contact" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<table border="1" >
<tr >
<th>编号</th>
<th>姓名</th>
<th>性别</th>
<th>年龄</th>
<th>籍贯</th>
<th>QQ</th>
<th>邮箱</th>
<th>操作</th>
</tr>
<c:forEach items="${list}" var="item" >
<tr >
<td>${
item.id}</td>
<td>${
item.name}</td>
<td>${
item.sex}</td>
<td>${
item.age}</td>
<td>${
item.address}</td>
<td>${
item.qq}</td>
<td>${
item.email}</td>
<td>删除</td>
</tr>
</c:forEach>
</table>
</body>
</html>