–Servlet 的优势与弊端 –JSP 的优势与弊端 –MVC 设计模式 –实例
?使用MVC实现学生信息的添加、显示-----------------------------START-----------------------------------? Servlet 的优势与弊端
–优势
?功能强大，可以调用任意的Java JDK API
?能够实现很多高级特征
?成熟
–弊端
?逻辑处理和内容展示很难分离
?开发效率低
–out.println(“”);
?维护成本高? JSP 的优势与弊端
–优势?可以直接嵌入静态HTML
?可以直接写代码
?开发效率高
–弊端
?如果直接在JSP页面中写代码
–程序可读性差
–维护困难? MVC设计模式
–MVC设计模式早在面向对象语言Smalltalk-80中就被提出并在此后得到业界的广泛接受
–它包括三类对象
?模型（Model）对象
–是应用程序的主体部分
?视图（View）对象
–是应用程序中负责生成用户界面的部分
?控制器（Control）对象
–是根据用户的输入，控制用户界面数据显示及更新Model对象状态的部分–MVC设计模式的好处
? MVC模式不仅实现了功能模块和显示模块的分离
?同时它还提高了应用系统的
–可维护性
–可扩展性
–可移植性
–组件的可复用性–JSP 的两种实现模式–具体实现? 实例 –使用MVC实现学生信息的添加、显示
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import com.michael.dao.StudentDao;
import com.michael.util.ConnectionUtil;
import com.michael.util.SQLConstants;
import com.michael.vo.Student;
public class StudentDaoImpl implements StudentDao,SQLConstants {
public void add(Student stu) {
Connection conn = new ConnectionUtil().openConnection();
//String sql = "insert into StudentTbl(name,age,email) values(?,?,?)";
try {
PreparedStatement pstmt = conn.prepareStatement(ADD_STUDENT_SQL);
pstmt.setString(1, stu.getName());
pstmt.setInt(2, stu.getAge());
pstmt.setString(3, stu.getEmail());
pstmt.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
}finally{
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
public List listStudent() {
Connection conn = new ConnectionUtil().openConnection();
//String sql = "insert into StudentTbl(name,age,email) values(?,?,?)";
try {
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(QUERY_STUDENT_SQL);
List list = new ArrayList();
while(rs.next()){
int id = rs.getInt(1);
String name = rs.getString(2);
int age = rs.getInt(3);
String email = rs.getString(4);
Student stu = new Student();
stu.setId(id);
stu.setName(name);
stu.setAge(age);
stu.setEmail(email);
list.add(stu);
}
return list;
} catch (SQLException e) {
e.printStackTrace();
}finally{
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
return null;
}
}
ConnectionUtil.javapackage com.michael.util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.util.Properties;
public class ConnectionUtil {
/**
* @param args
*/
public static void main(String[] args) {
ConnectionUtil cu = new ConnectionUtil();
System.out.println(cu.openConnection());
}
public Connection openConnection() {
String url = "";
String driver = "";
String user = "";
String password = "";
Properties prop = new Properties();
try {
prop.load(this.getClass().getClassLoader().getResourceAsStream("DBConfig.properties"));
driver = prop.getProperty("driver");
url = prop.getProperty("url");
user = prop.getProperty("user");
password = prop.getProperty("password");
Class.forName(driver);
Connection conn = DriverManager.getConnection(
url, user, password);
return conn;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
public Connection getConnection(String driver, String url, String user,
String password) {
// Class.forName()
try {
Class.forName(driver);
// DriverManager get connection
Connection conn = DriverManager.getConnection(url, user, password);
return conn;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
public Connection getConnection() {
// Class.forName()
try {
Class.forName("com.mysql.jdbc.Driver");
// DriverManager get connection
Connection conn = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/jsp_db", "root", "963963");
return conn;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}
SQLConstants.javaDBConfig.propertiesStudent.javaStudentDaoImplTest.java下面进行单元测试 数据库添加成功！ 下面继续哈~stu.jsp<%@ page language="java" import="java.util.*" pageEncoding="gbk"%>
<%@ taglib uri="/jsp/jstl/core" prefix="redking" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'stu.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<form name="f1" id="f1" action="<%=path %>/servlet/StuServlet?methodName=add" method="post">
<table border="0">
<tr>
<td>姓名:</td>
<td><input type="text" name="name"></td>
</tr>
<tr>
<td>年龄:</td>
<td><input type="text" name="age"></td>
</tr>
<tr>
<td>电邮:</td>
<td><input type="text" name="email"></td>
</tr>
<tr>
<td colspan="2" align="center"><input type="submit" value="添加"></td>
</tr>
</table>
</form>
<hr>
<table>
<tr><th>ID</th><th>Name</th><th>Age</th><th>Email</th></tr>
<redking:forEach>
<tr>
<td>${s.id }</td>
<td>${s.name }</td>
<td>${s.age }</td>
<td>${s.email }</td>
</tr>
</redking:forEach>
</table>
</body>
</html>
StuServlet.javapackage com.michael.servlet;
import java.io.IOException;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.michael.dao.StudentDao;
import com.michael.dao.impl.StudentDaoImpl;
import com.michael.vo.Student;
public class StuServlet extends HttpServlet {
/**
* Constructor of the object.
*/
public StuServlet() {
super();
}
/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request,response);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String methodName = request.getParameter("methodName");
if(methodName!=null&&methodName.equals("add")){
add(request,response);
}else{
query(request,response);
}
/*
//响应用户请求
String name = request.getParameter("name");
String age = request.getParameter("age");
String email = request.getParameter("email");
//调用后台逻辑
StudentDao dao = new StudentDaoImpl();
Student stu = new Student();
stu.setName(name);
stu.setAge(new Integer(age));
stu.setEmail(email);
dao.add(stu);
List list = dao.listStudent();
request.setAttribute("StuList", list);
//数据处理后跳转
request.getRequestDispatcher("/stu.jsp").forward(request,response);
*/
}
public void add(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//响应用户请求
String name = request.getParameter("name");
String age = request.getParameter("age");
String email = request.getParameter("email");
//调用后台逻辑
StudentDao dao = new StudentDaoImpl();
Student stu = new Student();
stu.setName(name);
stu.setAge(new Integer(age));
stu.setEmail(email);
dao.add(stu);
query(request,response);
}
public void query(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//调用后台逻辑
StudentDao dao = new StudentDaoImpl();
List list = dao.listStudent();
request.setAttribute("StuList", list);
// 跳转
request.getRequestDispatcher("/stu.jsp").forward(request, response);
}
/**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}
}
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