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Java Web学生信息管理系统实现简单的增删改查

程序员文章站 2022-05-08 14:47:24
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Java Web学生信息管理系统实现简单的增删改查

前言：
自己第一次接触Java Web应该是在闲鱼和一个大佬的“生意往来”，大二上学期刚学完Oracle，老师就要求用Java语言操作Oracle，当时真的是懵了。回顾自己前两年的生活，大一上学期学习C语言，下学期学习Java，当时教课老师是学硬件的。课上讲一些理论性的问题，剩余时间让我们比这课本敲代码，感觉自己学的Java太片面了，而且那个时候也没有感到Java很重要，直到现在真的后悔之前没有好好学习Java…现在想想，所谓的连接Oracle和MySQL区别也不是很大，JDBC连接数据库的步骤都是固定的，SQL语句也差不多，之间的区别就在，数据库所属的公司不同，驱动jar包不同，具体的驱动类不同，或许，想到更细致一点，数据库的用户名和密码不同。现在，JSP，servlet，三层架构，MVC框架，前端技术（ HTML CSS JS …）涉及的知识范围越广，理解起来其实也更加的容易。

Oracle数据库：

  • 驱动jar包（从官网进行下载）：ojdbc-x.jar
  • 具体驱动类：oracle.jdbc.OracleDriver

MySQL数据库

  • 驱动jar包：mysql-connection-java-x.jar
  • 具体驱动类：com.mysql.jdbc.Driver

下面是具体的项目管理：
主页面：显示全部学生信息index.jsp

查询操作：
Java Web学生信息管理系统实现简单的增删改查

更新修改操作：
Java Web学生信息管理系统实现简单的增删改查
增加操作：
Java Web学生信息管理系统实现简单的增删改查

点击删除（超链接）后，数据库中对应的数据成功删除（这里不再展示）

实现代码：

StudentDao.java

package org.student.dao;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import org.student.entity.Student;


/**
 * @author 11441
 *数据访问层：原子性，具体的 增删改查
 */
public class StudentDao {
	
	private final String URL = "jdbc:mysql://localhost:3306/test1";
	private final String USERNAME = "root";
	private final String PASSWOED = "root";
	
	//判断学生存在
	public boolean isExist(int sno) {
		return queryStudentBySno(sno)==null ? false : true;
	}
	
	//增加
	public boolean addStudent(Student student) {
		//封装到数据类
		Connection connection = null;
		PreparedStatement pstmt = null;
		try {
			Class.forName("com.mysql.jdbc.Driver");
			connection = DriverManager.getConnection(URL, USERNAME, PASSWOED);
			String sql = "insert into student values (?,?,?,?)";
			pstmt = connection.prepareStatement(sql);
			pstmt.setInt(1, student.getSno());
			pstmt.setString(2, student.getSname());
			pstmt.setInt(3, student.getSage());
			pstmt.setString(4, student.getSaddress());
			int count = pstmt.executeUpdate();
			if(count > 0) {
				return true;
			}else {
				return false;
			}
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
			return false;
		} catch (SQLException e) {
			e.printStackTrace();
			return false;
		} catch (Exception e) {
			e.printStackTrace();
			return false;
		} finally {
			try {
				if(pstmt != null) pstmt.close();
				if(connection != null) connection.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}
	
	//根据学号修改学生:根据sno找到要修改的人
	public boolean updateStudentBySno(int sno,Student student) {
		Connection connection = null;
		PreparedStatement pstmt = null;
		try {
			Class.forName("com.mysql.jdbc.Driver");
			connection = DriverManager.getConnection(URL, USERNAME, PASSWOED);
			String sql = "update student set sname = ?,sage=?,saddress=? where sno=?";
			pstmt = connection.prepareStatement(sql);
			pstmt.setString(1, student.getSname());
			pstmt.setInt(2, student.getSage());
			pstmt.setString(3, student.getSaddress());
			
			pstmt.setInt(4, sno);
			int count = pstmt.executeUpdate();
			if(count > 0) {
				return true;
			}else {
				return false;
			}
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
			return false;
		} catch (SQLException e) {
			e.printStackTrace();
			return false;
		} catch (Exception e) {
			e.printStackTrace();
			return false;
		} finally {
			try {
				if(pstmt != null) pstmt.close();
				if(connection != null) connection.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}
	//根据学号删除学生
	public boolean deleteStudentBySno(int sno) {
		//封装到数据类
			Connection connection = null;
			PreparedStatement pstmt = null;
			try {
				Class.forName("com.mysql.jdbc.Driver");
				connection = DriverManager.getConnection(URL, USERNAME, PASSWOED);
				String sql = "delete from student where sno = ?";
				pstmt = connection.prepareStatement(sql);
				pstmt.setInt(1, sno);
				int count = pstmt.executeUpdate();
				if(count > 0) {
					return true;
				}else {
					return false;
				}
			} catch (ClassNotFoundException e) {
				e.printStackTrace();
				return false;
			} catch (SQLException e) {
				e.printStackTrace();
				return false;
			} catch (Exception e) {
				e.printStackTrace();
				return false;
			} finally {
				try {
					if(pstmt != null) pstmt.close();
					if(connection != null) connection.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
	}
	//根据学号查询学生信息
	public Student queryStudentBySno(int sno) {
		Student student = null;
		Connection connection = null;
		PreparedStatement pstmt = null;
		ResultSet rs = null;
		try {
			Class.forName("com.mysql.jdbc.Driver");
			connection = DriverManager.getConnection(URL, USERNAME, PASSWOED);
			String sql = "select * from student where sno = ?";
			pstmt = connection.prepareStatement(sql);
			pstmt.setInt(1, sno);
			rs = pstmt.executeQuery();
			if(rs.next()) {
				int no = rs.getInt("sno");
				String name = rs.getString("sname");
				int age = rs.getInt("sage");
				String address = rs.getString("saddress");
				student = new Student(no,name,age,address);
			}
			return student;
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
			return null;
		} catch (SQLException e) {
			e.printStackTrace();
			return null;
		} catch (Exception e) {
			e.printStackTrace();
			return null;
		} finally {
			try {
				if(rs != null) rs.close();
				if(pstmt != null) pstmt.close();
				if(connection != null) connection.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}
	//查询全部学生(很多学生)
	public List<Student> queryAllStudent() {
		List<Student> students = new ArrayList<>();
		Student student = null;
		Connection connection = null;
		PreparedStatement pstmt = null;
		ResultSet rs = null;
		try {
			Class.forName("com.mysql.jdbc.Driver");
			connection = DriverManager.getConnection(URL, USERNAME, PASSWOED);
			String sql = "select * from student";
			pstmt = connection.prepareStatement(sql);
			rs = pstmt.executeQuery();
			while(rs.next()) {
				int no = rs.getInt("sno");
				String name = rs.getString("sname");
				int age = rs.getInt("sage");
				String address = rs.getString("saddress");
				student = new Student(no,name,age,address);
				students.add(student);
			}
			return students;
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
			return null;
		} catch (SQLException e) {
			e.printStackTrace();
			return null;
		} catch (Exception e) {
			e.printStackTrace();
			return null;
		} finally {
			try {
				if(rs != null) rs.close();
				if(pstmt != null) pstmt.close();
				if(connection != null) connection.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}
}

Student.java

package org.student.entity;

/**
 * @author 11441
 *student实体类
 */
public class Student {
	private int sno;
	private String sname;
	private int sage;
	private String saddress;
	public Student(String sname, int sage, String saddress) {
		this.sname = sname;
		this.sage = sage;
		this.saddress = saddress;
	}
	public Student(int sno, String sname, int sage, String saddress) {
		this.sno = sno;
		this.sname = sname;
		this.sage = sage;
		this.saddress = saddress;
	}
	public Student() {
		
	}
	public Student(int sno, String sname, int sage) {
		this.sno = sno;
		this.sname = sname;
		this.sage = sage;
	}
	public Student(int sage, String saddress) {
		this.sage = sage;
		this.saddress = saddress;
	}
	public int getSno() {
		return sno;
	}
	public void setSno(int sno) {
		this.sno = sno;
	}
	public String getSname() {
		return sname;
	}
	public void setSname(String sname) {
		this.sname = sname;
	}
	public int getSage() {
		return sage;
	}
	public void setSage(int sage) {
		this.sage = sage;
	}
	public String getSaddress() {
		return saddress;
	}
	public void setSaddress(String saddress) {
		this.saddress = saddress;
	}
	@Override
	public String toString() {
		return this.getSno()+"-"+this.getSname()+"-"+this.getSage()+"-"+this.getSaddress();
	}
}

StudentService.java

package org.student.service;

import java.util.List;

import org.student.dao.StudentDao;
import org.student.entity.Student;

/**
 * @author 11441
 *业务逻辑层，逻辑性的增删改查，（增：查+增）到Dao层进行的组装
 */
public class StudentService {
	StudentDao studentDao = new StudentDao();
	public boolean addStudent(Student student) {
		if(!studentDao.isExist(student.getSno())) {
			//学生不存在，增加该学生
			studentDao.addStudent(student);
			return true;
		}else {
			System.out.println("该学生已存在");
			return false;
		}
	}
	public boolean deleteStudentBySno(int sno) {
		if(studentDao.isExist(sno)) {
			return studentDao.deleteStudentBySno(sno);
		}else {
			return false;
		}
	}
	public boolean updateStudentBySno(int sno,Student student) {
		if(studentDao.isExist(sno)) {
			return studentDao.updateStudentBySno(sno,student);
		}else {
			return false;
		}
	}
	//根据学号查询学生
	public Student queryStudentBySno(int sno) {
		return studentDao.queryStudentBySno(sno);
	}
	//查询所有学生
	public List<Student> queryAllStudents() {
		return studentDao.queryAllStudent();
	}
}

QueryAllStudentdServlet.java
（关于Servlet还有AddStudentServlet，DeleteStudentServlet，QueryStudentBySnoServlet，UpdateStudentServlet，这里就不再展示）

package org.student.servlet;

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.student.entity.Student;
import org.student.service.StudentService;

public class QueryAllStudentdServlet extends HttpServlet {
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		
		StudentService service = new StudentService();
		List<Student> students = service.queryAllStudents();
		
		System.out.println(students);
		request.setAttribute("students", students);
		
		//因为request域中有数据，因此需要通过请求转发的方式跳转（重定向会丢失request域）
		request.getRequestDispatcher("index.jsp").forward(request, response);
	}
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
	}
}

WebContent中的jsp文件：

index.jsp

<%@page import="org.student.service.StudentService"%>
<%@page import="org.student.dao.StudentDao"%>
<%@page import="java.util.List"%>
<%@page import="org.student.entity.Student"%>
<%@page import="org.student.servlet.QueryAllStudentdServlet"%>
<%@ 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>学生信息列表</title>
<style type="text/css">
#formstyle
{
	margin:100px 500px;
}
table{
	width: 80%;
	height: 100%;
}
</style>
</head>
<body background="photo/海浪.jpg">
<div id="formstyle">
	<table border="#008C8C 3px solid">
		<caption>学生信息管理系统</caption>
		<tr align="left" >
			<th>学号</th>
			<th>姓名</th>
			<th>年龄</th>
			<th>操作</th>
		</tr>
		<!-- 学生信息有几行，要通过循环 -->
		<%
		/* 获取request域中的数据 */
			List<Student> students = (List<Student>)request.getAttribute("students");
			for(Student student : students){
		%>
			<tr>
				<td><a href="QueryStudentBySnoServlet?sno=<%=student.getSno() %>"><%=student.getSno()%></a></td>
				<td><%=student.getSname()%></td>
				<td><%=student.getSage()%></td>
				<td><a href="DeleteStudentServlet?sno=<%=student.getSno()%>">删除</a></td>			
			</tr>
		<%
			}
		%>
	</table>
	<a href="add.jsp">新增</a>
</div>
</body>
</html>

add.jsp

<%@page import="org.student.entity.Student"%>
<%@ 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>
	<%
		Student student = (Student)request.getAttribute("student");
	%>	
	<!--通过表单展示学生 -->
	<form action="UpdateStudentServlet">
		学号：<input type="text" name="sno" value="<%=student.getSno() %>" readonly="readonly" /><br/>
		姓名：<input type="text" name="sname" value="<%=student.getSname() %>"/><br/>
		年龄：<input type="text" name="sage" value="<%=student.getSage() %>"/><br/>
		地址：<input type="text" name="saddress" value="<%=student.getSaddress() %>"/><br/>
		<input type="submit" value=" 修改" /><br/>
		<a href="QueryAllStudentdServlet">返回</a>
	</form>
</body>
</html>

studentInfo.jsp

<%@page import="org.student.entity.Student"%>
<%@ 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>
	<%
		Student student = (Student)request.getAttribute("student");
	%>	
	<!--通过表单展示学生 -->
	<form action="UpdateStudentServlet">
		学号：<input type="text" name="sno" value="<%=student.getSno() %>" readonly="readonly" /><br/>
		姓名：<input type="text" name="sname" value="<%=student.getSname() %>"/><br/>
		年龄：<input type="text" name="sage" value="<%=student.getSage() %>"/><br/>
		地址：<input type="text" name="saddress" value="<%=student.getSaddress() %>"/><br/>
		<input type="submit" value=" 修改" /><br/>
		<a href="QueryAllStudentdServlet">返回</a>
	</form>
</body>
</html>

总结
web项目中信息在各个层次之间的传递的过程，跳转页面重定向和请求转发的区别，在JSP中怎样获取参数，调用方法等各种细节，需要不断的练习

相关标签： JAVA java jsp servlet

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