JSP代码 MVC编程开发实例

我之前一直搞不明白javabean在mvc中到底充当一个什么角色。现在来看一个实例

定义一个javabean
package com.bean;
public class user {
    private string username;
    private string userpwd;
    public string getusername() {
        return username;
    }

    public void setusername(string username) {
        this.username = username;
    }

    public string getuserpwd() {
        return userpwd;
    }

    public void setuserpwd(string userpwd) {
        this.userpwd = userpwd;
    }
}

javabean的作用：是一个po对象之前我以为是vo对象。搞错了！

恩我们可以这样来理解javabean的作用其实就是用来传递数据的一个东西。在我们这次phpcms项目中相当于一个结果集的传输。控制器接收到一个来自m层的数据之后如何传递到视图层作渲染处理。可以依据这样的方式。

再来看我们的action类
package com.dao;
import java.sql.*;
import com.bean.user;
public class dao {
    connection conn = null;
    statement stmt = null;
    resultset rs = null;
    preparedstatement pstmt = null
    public dao(){
        try {
            class.forname("com.mysql.jdbc.driver");
            conn = getconnection();
        } catch (classnotfoundexception e) {
            // todo auto-generated catch block
            e.printstacktrace();
        }
    }

    public connection getconnection(){
        string url = "jdbc:mysql://localhost:3306/person";
        string user = "root";
        string password = "123456";
        try {
            conn = drivermanager.getconnection(url, user, password);
        } catch (sqlexception e) {
            // todo auto-generated catch block
            e.printstacktrace();
        }
        return conn;
    }

    public int addperson(user user){
        int flag = 0;
        string sql = "insert into user(user_name,user_pwd) values(?,?)";
        try {
            pstmt = conn.preparestatement(sql);
            pstmt.setstring(1, user.getusername());
            pstmt.setstring(2, user.getuserpwd());
            flag = pstmt.executeupdate();

        } catch (sqlexception e) {
            // todo auto-generated catch block
            e.printstacktrace();
        }
        return flag;
    }

    public resultset showperson(){
        string sql = "select * from user";
        try {
            pstmt = conn.preparestatement(sql);
            rs = pstmt.executequery();
        } catch (sqlexception e) {
            // todo auto-generated catch block
            e.printstacktrace();
        }
        return rs;
    }

    public void close(){
        try {
            if(rs!=null)rs.close();
            if(pstmt!=null)pstmt.close();
            if(conn!=null)conn.close();

        } catch (sqlexception e) {
            // todo auto-generated catch block
            e.printstacktrace();
        }
    }
}

这个类把连接操作也放在这里了。其实是不正确的处理方式。正确的方式应当是将数据库层单独写到一个class类里面去。但这里面我们来看一下：

public int addperson(user user){
        int flag = 0;
        string sql = "insert into user(user_name,user_pwd) values(?,?)";
        try {
            pstmt = conn.preparestatement(sql);
            pstmt.setstring(1, user.getusername());
            pstmt.setstring(2, user.getuserpwd());
            flag = pstmt.executeupdate();
        } catch (sqlexception e) {
            // todo auto-generated catch block
            e.printstacktrace();
        }
        return flag;
    }

这个dao对象它的作用是接收来自javabean层的数据。

再看是如何set值到这个bean的

package com.servlet;
 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 com.bean.user;
 import com.dao.dao;
 public class adduser extends httpservlet {
 public void doget(httpservletrequest request, httpservletresponse response)
        throws servletexception, ioexception {
        string username = request.getparameter("username");
        string userpwd = request.getparameter("userpwd");
        user user = new user();
        user.setusername(username);//依据的是set与get方式了吧！！！！
        user.setuserpwd(userpwd);
        dao dao = new dao();