首先我们应该了解什么是MVC：
MVC包含三个部分 ：
①View：由各种JSP页面组成。
②Controller：由各种Servlet组成，Controller就是将View和Model来进行匹配，用什么Model实现，调用哪个View来显示。
③Model：由各种javabean组成，也是MVC的核心，
以下就是简单的用MVC架构去实现一个JSP（View）+Servlet（Controller）+javabean（Model）实现MySql查询功能的Demo。
创建Web Project
1.打开MyEclipse -> File-> new -> Web Project 创建完后在src下创建包beans和ServletDB最后得到例如以下的文件结构：
2.编写beans
在beans包下创建两个javabeans分别为DAL.java 和 DB.java
DB.java 注意MySqlusername和password是你本机MySql的 username和password与下面的代码可能不一样须要改动。
package beans;
import java.sql.*;
public class DB {
static String driver = "com.mysql.jdbc.Driver";
static String url = "jdbc:mysql://127.0.0.1:3306/test";
static String user = "root";//连接时的username
static String password = "root";//连接时的密码
static Connection aConnection;
public static Connection connectDB(){
try{
Class.forName(driver);
aConnection = DriverManager.getConnection(url,user,password);
if(aConnection.isClosed())
{
System.out.print("Succeeded!");
}
}catch(ClassNotFoundException e){
System.out.println(e);
} catch (SQLException e) {
e.printStackTrace();
}
return aConnection;
}
public static ResultSet executeQuery(String sqlx) throws SQLException{
connectDB();
ResultSet rs = null;
Statement stmt = aConnection.createStatement();
try {
rs = stmt.executeQuery(sqlx);
} catch (SQLException e) {
e.printStackTrace();
}
return rs;
}
}
DAL.java
package beans;
import java.sql.ResultSet;
import java.sql.SQLException;
public class DAL {
public static String sqlx="";
public static String testQueryByID(String ID){
ResultSet rs = null;
String result = "";
sqlx = "SELECT * FROM testtable where ID = '"+ID+"'";
try {
rs = DB.executeQuery(sqlx);
} catch (SQLException e) {
e.printStackTrace();
}
try {
while(rs.next()){
result = result +"ID:"+rs.getString("ID")+" Name:"+rs.getString("name")+"</br>";
}
} catch (SQLException e) {
e.printStackTrace();
}
return result;
}
}
3.编写servlet
File-> new -> servlet->确定包名为servletDB然后取名为test即可了
重要的是在本test方法中增加调用beans方法的语句。
test.java
package servletDB; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import beans.DAL; public class test extends HttpServlet { /** * Constructor of the object. */ public test() { super(); } /** * Destruction of the servlet. <br> */ public void destroy() { super.destroy(); // Just puts "destroy" string in log // Put your code here } public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); String ID = request.getParameter("ID");//获取传过来的ID String result = ""; result = DAL.testQueryByID(ID);//调用DAL中的testQueryByID方法而且将get过来的ID传过去 PrintWriter out = response.getWriter(); out.println("<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">"); out.println("<HTML>"); out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>"); out.println(" <BODY>"); out.print(result); out.println(" </BODY>"); out.println("</HTML>"); out.flush(); out.close(); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); PrintWriter out = response.getWriter(); out.println("<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">"); out.println("<HTML>"); out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>"); out.println(" <BODY>"); out.print(" This is "); out.print(this.getClass()); out.println(", using the POST method"); out.println(" </BODY>"); out.println("</HTML>"); out.flush(); out.close(); } public void init() throws ServletException { // Put your code here } }
4.配置Servlet
进入WebRoot-〉Web-INF -〉web.xml加入例如以下代码
<servlet-name>test</servlet-name> <servlet-class>servletDB.test</servlet-class> </servlet> <servlet-mapping> <servlet-name>test</servlet-name> <url-pattern>/servletDB/test</url-pattern>
写index.jsp
将body中的代码替换为例如以下代码
<form action="servletDB/test" method="get"> 请输入用户ID：<input type="text" name="ID"><br> <input type="submit" value="提交"> </form>
測试
1.点击Run
2.输入測试ID 1
成功的获取到了test数据库testtable中ID为1的数据。
转载于 MVC jsp+servlet+javabean 连接Mysql数据库測试demo_weixin_33816300的博客-CSDN博客