MVC jsp+servlet+javabean 连接Mysql数据库測试demo

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

posted @ 2020-11-24 21:55 vkd 阅读(259) 评论(0) 收藏举报

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vkd

MVC jsp+servlet+javabean 连接Mysql数据库測试demo

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