JAVA 学习日记(5).JSP，JDBC数据库查询

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1.JSP
实例1：在网页上显示当前时间

index.html<%@page import="java.text.SimpleDateFormat"%><%@ page language="java" import="java.util.*" contentType="text/html" pageEncoding="utf-8"%><%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 'index.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>    <% SimpleDateFormat format=new SimpleDateFormat("yyy年MM月dd日   hh时mm分ss秒");    String time=format.format(new Date());     %>     <%=time %>  </body></html>

实例2：实现登录功能，并捕获登录信息。

login.jsp<%@ page language="java" import="java.util.*" contentType="text/html; charset=UTF-8"%><%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 'login.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 action="dologin.jsp" method="post">        用户名：<input type="text" name="username" /><br>        密码：<input type="password" name="password" /><br>        兴趣爱好：<input type="checkbox" name="hobby" value="足球"/>足球                <input type="checkbox" name="hobby" value="排球"/>排球                <input type="checkbox" name="hobby" value="篮球"/>篮球<br>                <input type="submit" value="立即登录">    </form>  </body></html>

dologin.jsp<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%><%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 'dologi.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>    <%        request.setCharacterEncoding("utf-8");        String user=request.getParameter("username");        String pwd=request.getParameter("password");        String[] hobby=request.getParameterValues("hobby");            for(int i=0;i<hobby.length;i++){            out.println(hobby[i]);        }     %>     <%="用户名："+user+" "+"密码："+pwd %>  </body></html>

2.JDBC数据库查询
实例：使用JDBC和SQL语句查询数据库信息

目录结构：
这里写图片描述

数据库信息：
这里写图片描述

DBUtil.javapackage com.zrgj.shanji.util;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;/** * 数据库连接 * @author Administrator * */public class DBUtil {//  导包    public DBUtil(){        try {            Class.forName("com.mysql.jdbc.Driver");        } catch (ClassNotFoundException e) {            e.printStackTrace();        }    }//  创建连接    public Connection getConn(){        Connection conn=null;        try {            conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/student?useUnicode=true&characterEncoding=UTF-8","root","root");        } catch (SQLException e) {            e.printStackTrace();        }        return conn;    }//  关闭资源    public static void closeAll(ResultSet rs,PreparedStatement pstmt,Connection conn){        try {            if (rs!=null) {                rs.close();            }            if(pstmt!=null){                pstmt.close();            }            if (conn!=null) {                conn.close();            }        }catch (SQLException e) {            e.printStackTrace();        }    }       }

StudentDao.javapackage com.zrgj.shanji.dao;import com.zrgj.shanji.entity.Student;public interface StudentDao {    public Student getStudent(String studynum);}

StudentDaoImpl.javapackage com.zrgj.shanji.dao.impl;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import com.zrgj.shanji.dao.StudentDao;import com.zrgj.shanji.entity.Student;import com.zrgj.shanji.util.DBUtil;public class StudentDaoImpl implements StudentDao {    DBUtil db=new DBUtil();    private Connection conn=null;    private PreparedStatement pstmt=null;    private ResultSet rs=null;    public Student getStudent(String studynum) {        Student stu=null;        String sql="select * from student where studynum="+"'"+studynum+"'";        conn=db.getConn();        try {            pstmt=conn.prepareStatement(sql);            rs=pstmt.executeQuery();            while(rs.next()){                stu=new Student();                int sid=rs.getInt("sid");                String sname=rs.getString("sname");                String spwd=rs.getString("spwd");                String gender=rs.getString("gender");                stu.setSid(sid);                stu.setSname(sname);                stu.setSpwd(spwd);                stu.setGender(gender);            }        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        return stu;    }       }

Student.javapackage com.zrgj.shanji.entity;public class Student {    private int sid;    private String sname;    private String spwd;    private String gender;    private String studynumString;    public int getSid() {        return sid;    }    public void setSid(int sid) {        this.sid = sid;    }    public String getSname() {        return sname;    }    public void setSname(String sname) {        this.sname = sname;    }    public String getSpwd() {        return spwd;    }    public void setSpwd(String spwd) {        this.spwd = spwd;    }    public String getGender() {        return gender;    }    public void setGender(String gender) {        this.gender = gender;    }    public String getStudynumString() {        return studynumString;    }    public void setStudynumString(String studynumString) {        this.studynumString = studynumString;    }   }

StudentTest.javapackage test;import com.zrgj.shanji.dao.StudentDao;import com.zrgj.shanji.dao.impl.StudentDaoImpl;import com.zrgj.shanji.entity.Student;public class StudentTest {    public static void main(String[] args) {        StudentDao stuDao=new StudentDaoImpl();        Student stu=stuDao.getStudent("119120110");        System.out.println(stu.getSname());    }}

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