案例1：基于jsp+Servlet实现用户登录验证
1.input.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="loginCheck" method="post">
用户名：<input type="text" name="username" /><br> 密码：<input
type="password" name="userpwd" /><br> <input type="submit"
value="提交"> <input type="reset">
</form>
</body>
</html>2.loginCheckServlet.java
package servlets;
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;
@WebServlet("/loginCheck")
public class LoginCheckServlet extends HttpServlet {
public void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException{
String userName = request.getParameter("username");
String userPwd = request.getParameter("userpwd");
String info = "";
if("abc".equals(userName)&&"123".equals(userPwd)) {
info="欢迎你"+userName;
}else {
info="用户名或密码错误";
}
request.setAttribute("outputMessage", info);
request.getRequestDispatcher("/info.jsp").forward(request, response);
}
}
3.info.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<%=request.getAttribute("outputMessage") %>
</body>
</html>案例2：基于jsp+Servlet+JavaBean实现用户注册
1.数据库连接类
package db;
import java.sql.*;
public class JdbcUtil {
public static Connection getConnection() throws Exception{
String driverName = "com.mysql.jdbc.Driver";
String dbName = "students";
String userName = "root";
String userPwd = "1234";
String url1 = "jdbc:mysql://localhost:3306/"+dbName;
String url2 = "?user="+userName+"&password="+userPwd;
String url3 = "&useUnicode=true&characterEncoding=UTF-8";
String url = url1+url2+url3;
Class.forName(driverName);
Connection conn = DriverManager.getConnection(url);
return conn;
}
public static void free(ResultSet rs,PreparedStatement pstmt,Connection conn) throws SQLException {
if(rs!=null) {
rs.close();
}
if(pstmt!=null) {
pstmt.close();
}
if(conn!=null) {
conn.close();
}
}
}
2.javabean实体类
package beans;
public class User {
private String userName;
private String userPwd;
public User(String userName,String userPwd) {
this.userName = userName;
this.userPwd = 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;
}
public User() {}
}
3.数据库访问类dao
package dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;
import javax.swing.plaf.basic.BasicInternalFrameTitlePane.RestoreAction;
import beans.User;
import db.JdbcUtil;
public class UserDao {
//添加
public void add(User user) throws Exception{
Connection conn = null;
PreparedStatement pstmt = null;
conn = JdbcUtil.getConnection();
String sql = "insert into user_b(username,userpassword) values(?,?)";
pstmt = conn.prepareStatement(sql);
pstmt.setString(1, user.getUserName());
pstmt.setString(2, user.getUserPwd());
pstmt.executeUpdate();
JdbcUtil.free(null, pstmt, conn);
}
//查询全部
public List<User> QueryAll() throws Exception{
Connection conn = null;
PreparedStatement pstmt = null;
ResultSet rs = null;
List<User> UserList = new ArrayList<User>();
conn = JdbcUtil.getConnection();
String sql = "select * from user_b";
pstmt = conn.prepareStatement(sql);
rs = pstmt.executeQuery();
while(rs.next()) {
String xm = rs.getString("username");
String mm = rs.getString("password");
User user = new User(xm,mm);
UserList.add(user);
}
JdbcUtil.free(rs, pstmt, conn);
return UserList;
}
//修改
public int update(User user) throws Exception{
Connection conn = null;
PreparedStatement pstmt = null;
int result = 0;
conn = JdbcUtil.getConnection();
String sql = "update user_b set userpassword=? where username=?";
pstmt.setString(1, user.getUserName());
pstmt.setString(2, user.getUserPwd());
result = pstmt.executeUpdate();
JdbcUtil.free(null, pstmt, conn);
return result;
}
//删除
public int delete(int username) throws Exception{
Connection conn = null;
PreparedStatement pstmt = null;
int result = 0;
conn = JdbcUtil.getConnection();
String sql = "delete from user_b where username=?";
pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, username);
result = pstmt.executeUpdate();
JdbcUtil.free(null, pstmt, conn);
return result;
}
}
4.注册页面a.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<form>
用户名：<input type="text" name="xm"><br>
<br> 密码：<input type="password" name="mm"><br>
<br> <input type="submit" value="提交">
</form>
</body>
</html>5.处理登录的servlet
6.结果页面b.jsp
例3：学生体质信息管理
student.java
package beans;
public class Student {
private int id;
private String name;
private String sex;
private int age;
private float weight;
private float height;
public Student() {}
public Student(int id,String name,String sex,int age,float weight,float height) {
this.id = id;
this.name = name;
this.sex = sex;
this.age = age;
this.weight = weight;
this.height = height;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public float getWeight() {
return weight;
}
public void setWeight(float weight) {
this.weight = weight;
}
public float getHeight() {
return height;
}
public void setHeight(float height) {
this.height = height;
}
}
studentDao.java
package Dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;
import org.apache.tomcat.dbcp.dbcp2.PStmtKey;
import com.sun.org.apache.xerces.internal.util.EntityResolver2Wrapper;
import Util.JdbcUtil;
import beans.Student;
public class StudentDao {
public Student create(Student stu) throws Exception{
Connection conn = JdbcUtil.getConnection();
String sql = "insert into stu_info (id,name,sex,age,weight,height) values(?,?,?,?,?,?)";
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, stu.getId());
pstmt.setString(2, stu.getName());
pstmt.setString(3, stu.getSex());
pstmt.setInt(4, stu.getAge());
pstmt.setFloat(5, stu.getWeight());
pstmt.setFloat(6, stu.getHeight());
pstmt.executeUpdate();
JdbcUtil.free(null, conn, pstmt);
return stu;
}
public List<Student> findAll() throws Exception{
Connection conn = JdbcUtil.getConnection();
String sql = "select * from stu_info";
PreparedStatement pstmt = conn.prepareStatement(sql);
ResultSet rs = null;
List<Student> students = new ArrayList<Student>();
rs = pstmt.executeQuery();
while(rs.next()) {
Student stu2 = new Student();
stu2.setId(rs.getInt(1));
stu2.setName(rs.getString(2));
stu2.setSex(rs.getString(3));
stu2.setAge(rs.getInt(4));
stu2.setWeight(rs.getFloat(5));
stu2.setHeight(rs.getFloat(6));
students.add(stu2);
}
JdbcUtil.free(rs, conn, pstmt);
return students;
}
public void remove(Student stu) throws Exception{
Connection conn = JdbcUtil.getConnection();
String sql = "delete from stu_info where name=?";
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setString(1, stu.getName());
pstmt.executeUpdate();
JdbcUtil.free(null, conn, pstmt);
}
public void update(Student stu) throws Exception{
Connection conn = JdbcUtil.getConnection();
String sql = "update stu_info set id=?,name=?,sex=?,age=?,weight=?,height=? where name=? ";
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, stu.getId());
pstmt.setString(2, stu.getName());
pstmt.setString(3, stu.getSex());
pstmt.setInt(4, stu.getAge());
pstmt.setFloat(5, stu.getWeight());
pstmt.setFloat(6, stu.getHeight());
pstmt.setString(7, stu.getName());
pstmt.executeUpdate();
JdbcUtil.free(null, conn, pstmt);
}
}
JdbcUtil.java
package Util;
import java.sql.*;
import java.sql.DriverManager;
import com.mysql.cj.jdbc.Driver;
public class JdbcUtil {
public static Connection getConnection() throws Exception {
String dbName = "students";
String driverName = "com.mysql.jdbc.Driver";
String userName = "root";
String userPwd = "1234";
String url1 = "jdbc:mysql://localhost:3306/"+dbName;
String url2 = "?user="+userName+"&password"+userPwd;
String url3 = "&useUnicode=true&characterEncoding=UTF-8";
String url = url1+url2+url3;
Class.forName(driverName);
Connection conn = DriverManager.getConnection(url);
return conn;
}
public static void free(ResultSet rs,Connection conn,PreparedStatement pstmt) throws Exception {
if(rs!=null) {
rs.close();
}
if(conn!=null) {
conn.close();
}
if(pstmt!=null) {
pstmt.close();
}
}
}
servlet: insert.java
package servlet;
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 Dao.StudentDao;
import beans.Student;
/**
* Servlet implementation class Insert
*/
@WebServlet("/Insert")
public class Insert extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public Insert() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
request.setCharacterEncoding("UTF-8");
int id = Integer.parseInt(request.getParameter("id"));
String name = request.getParameter("name");
String sex = request.getParameter("sex");
int age = Integer.parseInt(request.getParameter("age"));
Float weight = Float.parseFloat(request.getParameter("weight"));
Float height = Float.parseFloat("height");
Student stu = new Student(id,name,sex,age,weight,height);
StudentDao studentDao = new StudentDao();
studentDao.create(stu);
response.sendRedirect(StudentServlet?action=list);
response.getWriter().append("Served at: ").append(request.getContextPath());
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
list.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8" import="java.util.*" import="beans.Student"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>学生信息管理</title>
</head>
<body>
<a href="insert.jsp">添加学生</a>
<table>
<tr>
<th>学号</th>
<th>姓名</th>
<th>性别</th>
<th>年龄</th>
<th>体重</th>
<th>身高</th>
<th>操作</th>
</tr>
<%
List<Student> students = (List<Student>) request.getAttribute("students");
if (students != null && !students.isEmpty()) {
for (Student student : students) {
%>
<tr>
<td><%=student.getId()%></td>
<td><%=student.getName()%></td>
<td><%=student.getSex()%></td>
<td><%=student.getAge()%></td>
<td><%=student.getWeight()%></td>
<td><%=student.getHeight()%></td>
<td><a href="edit.jsp?name=<%=student.getName()%>">编辑</a> <a
href="delete.jsp?name=<%=student.getName()%>"
onclick="return confirm('确定要删除吗?')">删除</a></td>
</tr>
<%
}
}
%>
</table>
</body>
</html>insert.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="insert" method="post">
<table>
<tr>
<td>学号</td>
<td><input type="text" name="id"></td>
</tr>
<tr>
<td>姓名</td>
<td><input type="text" name="name"></td>
</tr>
<tr>
<td>性别</td>
<td><input type="text" name="sex"></td>
</tr>
<tr>
<td>年龄</td>
<td><input type="text" name="age"></td>
</tr>
<tr>
<td>体重</td>
<td><input type="text" name="weight"></td>
</tr>
<tr>
<td>身高</td>
<td><input type="text" name="height"></td>
</tr>
<tr>
<td><input type="submit" value="提交"></td>
</tr>
</table>
</form>
</body>
</html>