新手详解JAVA+数据库+JSP完成简单页面

本篇以数据库添加为例（本例中数据库名为“xinxi”表单名字为“stud”）

准备---实体层：

package entity;

public class Student {
    private String name;
    private String adress;
    private String qq;
    public void setName(String name) {
        this.name=name;
    }
    public String getName() {
        return name;
    }
    public void setAdress(String adress) {
        this.adress=adress;
    }
    public String getAdress() {
        return adress;
    }
    public void setQq(String qq) {
        this.qq=qq;
    }
    public String getQq() {
        return qq;
    }
    public Student() {
    }
    public Student(String n,String a,String q) {
        name=n;
        adress=a;
        qq=q;
    }
}

准备---连接数据库：

package util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class Shujuku {
     public static Connection conn(){
         String url="jdbc:sqlserver://localhost:1433;DatabaseName=xinxi";//填写你的数据库名
         String userName="sa";//填写你的用户名，我的是sa
         String userPwd="********";//填写你的密码
         Connection connection=null;

  try{
      Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
      System.out.println("加载驱动成功！");

  }catch(Exception e){

           e.printStackTrace();

           System.out.println("加载驱动失败！");
   }
 try{
    connection=DriverManager.getConnection(url,userName,userPwd);
 System.out.println("连接数据库成功！");
 }catch(Exception e){
        e.printStackTrace();
        System.out.print("SQL Server连接失败！");
  }
 return connection;
}
public static void close (Statement state, Connection conn) {//关闭
    if (state != null) {
        try {
            state.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    if (conn != null) {
        try {
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

public static void close (ResultSet rs, Statement state, Connection conn) {//关闭
    if (rs != null) {
        try {
            rs.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    if (state != null) {
        try {
            state.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    if (conn != null) {
        try {
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}
}

1.servlet（首先StuService ts=new StuService();//新建service实体对象，以便后来调用service中add()方法）

package servlet;
import service.*;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import entity.*;
@WebServlet("/StuServlet")
public class StuServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("utf-8");
        String method = request.getParameter("method");
        if(method.equals("add"))
        {
            add(request,response);
        }
    }
    StuService ts=new StuService();
    private void add(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        String name = req.getParameter("name");//从jsp中获取参数name
        String adress=req.getParameter("adress");
        String qq=req.getParameter("qq");
        Student stu=new Student(name,adress,qq);//新建
        int k=ts.add(stu);
        if(k==2) {
            req.setAttribute("message", "添加成功");//setAttribute方法用于将内容保存在对象中，传到add.jsp中
            req.getRequestDispatcher("add.jsp").forward(req,resp);//getRequestDispatcher方法用于进入下一个页面
        }
        if(k==0)
        {
            req.setAttribute("message", "重复，请重新录入");
            req.getRequestDispatcher("add.jsp").forward(req,resp);
        }
        if(k==1)
        {
            req.setAttribute("message", "数据库添加失败");
            req.getRequestDispatcher("add.jsp").forward(req,resp);
        }
    }
}

①创建方法add()，Servlet从jsp中获取参数，新建实体对象Student stu=new Student(name,adress,qq);

②调用service层，检验添加的准确性

StuService ts=new StuService();//新建service对象

if(ts.add(stu)){

//如果service对象ts的Boolean add(stu)方法返回真值true,页面要显示添加成功

//req.setAttribute("message", "添加成功");将"添加成功"内容保存在req对象参数message中，传递给add.jsp

//req.getRequestDispatcher("add.jsp").forward(req,resp);进入下一个界面（这里是add.jsp）

}

else{

//收到返回值为false，添加失败

//将 "重复，请重新录入"内容保存在req对象参数message中，传递给add.jsp

//进入下一个界面（这里是add.jsp）

}

2. Service（新建dao实体对象，后面要调用dao层方法）

package service;

import dao.StuDao;
import entity.Student;

public class StuService {
    StuDao sdao=new StuDao();
    public int add(Student stu) {
        int f=0;
        if(!sdao.rename(stu.getName())) {
            f=1;
            if(sdao.add(stu))
            f=2;
        }
        return f;
    }
}

①创建 add(Student stu){}方法，检验添加的准确性

②调用dao层后台程序方法rename（）检验是否重名

if(!sdao.rename(stu.getName())) {//如果没有重复

sdao.add(stu);//添加

f=true;//返回真值

}

如图，直接在提示错误中点击创建方法即可

3. Dao（后台程序）

在这里编写所需的底层程序：

rename()//验证名字是否唯一

Add()//添加

public class StuDao {

    public boolean rename(String name) {
        // 检验名字是否重复
        boolean f=false;
        String sql="select name from stud where name=‘"+name+"‘";//数据库语句，查询界面输入和表stud中name是否重复
        Connection conn = Shujuku.conn();//创建连接
        Statement state = null;//建立Statement对象，执行静态SQL语句
        ResultSet rs = null;//ResultSet对象 是查询数据库时的返回对象，读取返回结果集

        try {
            state = conn.createStatement();
            rs = state.executeQuery(sql);
            while (rs.next()) {//不重复，返回true
                f = true;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            Shujuku.close(rs, state, conn);
        }
        return f;
    }

    public boolean add(Student stu) {
        //添加
        String sql = "insert into stud(name,adress,qq) values(‘" +stu.getName() + "‘,‘" + stu.getAdress() + "‘,‘" + stu.getQq() + "‘)";
        Connection conn = Shujuku.conn();
        Statement state = null;
        boolean f = false;
        int a=0;
        try {
            state = conn.createStatement();
            a=state.executeUpdate(sql);//添加
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            Shujuku.close(state, conn);
        }
        if (a > 0) {
            f = true;
        }
        return f;
    }
}

4. Add.jsp

编写前端页面；

应用javascript验证客户端表单合法性。

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<%
         Object message = request.getAttribute("message");
         if(message!=null && !"".equals(message)){

%>
     <script type="text/javascript">
              alert("<%=request.getAttribute("message")%>");
         </script>
<%} %>
    <div align="center">
        <h1 style="color: red;">信息录入</h1>
        <a href="index.jsp">返回主页</a>
        <form action="StuServlet?method=add" method="post" onsubmit="return check()">
            <div >
                姓名<input type="text" id="name" name="name"/>
            </div>
            <div >
                联系方式<input type="text" id="qq" name="qq" />
            </div>
            <div >
                地址<input type="text" id="adress" name="adress" />
            </div>
            <div >
                <button type="submit" >保&nbsp;&nbsp;&nbsp;存</button>
            </div>
        </form>
    </div>
    <script type="text/javascript">
        function check() {
            var name = document.getElementById("name");;
            var qq = document.getElementById("qq");
            var adress = document.getElementById("adress");

            //非空
            if(name.value == ‘‘) {
                alert(‘名字为空‘);
                name.focus();
                return false;
            }
            if(qq.value == ‘‘) {
                alert(‘联系方式为空‘);
                qq.focus();
                return false;
            }
            if(adress.value == ‘‘) {
                alert(‘地址为空‘);
                adress.focus();
                return false;
            }
        }
    </script>
</body>
</html>

原文地址：https://www.cnblogs.com/sengzhao666/p/10181806.html