javaweb P24 三层架构 jsp-servlet-services-dao课堂笔记

川长思鸟来 2023-02-25 02:05 12阅读 0赞

## 三层架构—增删改查—增 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L21tbW1tbW1tbW16_size_16_color_FFFFFF_t_70]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L21tbW1tbW1tbW16_size_16_color_FFFFFF_t_70 1]  
1.在Mysql中创建表“student”

CREATE TABLE student(sno INT PRIMARY KEY,sname VARCHAR(20),sage INT,saddress VARCHAR(20));

2.创建ThreeTierSample项目，并创建add.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="AddStudentServlet" method="post" >
    	    学号：<input type="text" name="sno" /><br/>
    	    姓名：<input type="text" name="sname" /><br/>
    	    年龄：<input type="text" name="sage" /><br/>
    	    地址：<input type="text" name="saddress" /><br/>
    	    <input type="submit" value="新增" /><br/>
    	
    	
    	</form>
    </body>
    </html>

3.创建四个类中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 org.student.entity.Student; //数据访问层：原子性的，不可拆的增删改查 public class StudentDao { 
    	private final String URL="jdbc:mysql://localhost:3306/myemployees?serverTimezone=UTC";
    	private final String USERNAME="root";
    	private final String PASSWORD="123456"; public boolean isExist(int sno) { //true此人存才，flase此人不存在
    		return queryStudentBySno(sno)==null?false:true;
    	}
    //*******************根据信息，增加学生***************************************************************************************** public boolean addStudent(Student student) { 
    //		Student student=null;
    		Connection connection=null;
    //		ResultSet rs=null;
    		PreparedStatement pstmt=null; try { 
    		Class.forName("com.mysql.jdbc.Driver");
    		 connection = DriverManager.getConnection(URL,USERNAME,PASSWORD);
    		 String sql="insert into student(sno,sname,sage,saddress)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();
    				}
    		}	
    	}
    //******根据学号查学生，如果有就返回学生，如果没有返回null************************************* public Student queryStudentBySno(int sno)  { 
    		Student student=null;
    		Connection connection=null;
    		ResultSet rs=null;
    		PreparedStatement pstmt=null; try { 
    		Class.forName("com.mysql.jdbc.Driver");
    		 connection = DriverManager.getConnection(URL,USERNAME,PASSWORD);
    		 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();
    				}
    			
    		}
    		
    		
    	}
    }

4.创建四个类中Studentservice.java：

package org.student.service;
    
    import org.student.dao.StudentDao;
    import org.student.entity.Student; //业务逻辑层：逻辑性的增删改查 public class StudentService { 
    	public boolean addStudent(Student student) { 
    		StudentDao studentDao=new StudentDao(); if(!studentDao.isExist(student.getSno())) { 
    			studentDao.addStudent(student);
    			return true;
    		}else { 
    			System.out.println("此人已存在");
    			return false;
    		}
    	}
    
    }

5.创建四个类中Student.java：

package org.student.entity; public class Student { 
    	private int sno;
    	private String sname;
    	private int sage;
    	private String saddress; public Student() { 
    		
    	}
    	public Student(int sage, String saddress) { 
    		
    		this.sage = sage;
    		this.saddress = saddress;
    	}
    	public Student(int sno, String sname, int age, String saddress) { 
    		super();
    		this.sno = sno;
    		this.sname = sname;
    		this.sage = age;
    		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 age) { 
    		this.sage = age;
    	}
    	public String getSaddress() { 
    		return saddress;
    	}
    	public void setSaddress(String saddress) { 
    		this.saddress = saddress;
    	}
    	
    
    }

5.创建四个类中AddStudentServlet.java：

package org.student.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 org.student.entity.Student;
    import org.student.service.StudentService; public class AddStudentServlet extends HttpServlet { 
    
    	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
    		request.setCharacterEncoding("utf-8");
    		int no=Integer.parseInt(request.getParameter("sno"));
    		String name=request.getParameter("sname");
    	int age=Integer.parseInt(request.getParameter("sage"));
    	String address=request.getParameter("saddress");
    	Student student=new Student(no,name,age,address);
    //	student.getSage();
    //	student.getSno();
    //	student.getSname();
    //	student.getSaddress();
    	StudentService studentservice=new StudentService();
    	boolean result = studentservice.addStudent(student);
    	response.setContentType("text/html; charset=UTF-8");
    	response.setCharacterEncoding("utf-8");
    	PrintWriter out = response.getWriter();//响应对象 if(result) { 
    		out.print("增加成功！");
    	}else { 
    		out.print("增加失败！");
    	}
    	} 
    
    	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
    		doGet(request, response);
    	}
    
    }

6.看一下成品  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L21tbW1tbW1tbW16_size_16_color_FFFFFF_t_70 2]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L21tbW1tbW1tbW16_size_16_color_FFFFFF_t_70 3]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L21tbW1tbW1tbW16_size_16_color_FFFFFF_t_70 4]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L21tbW1tbW1tbW16_size_16_color_FFFFFF_t_70]: /images/20230209/44ec5b82935648a8a8b62c8b247ff3ed.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L21tbW1tbW1tbW16_size_16_color_FFFFFF_t_70 1]: /images/20230209/727da3ac694144f6b36200542b15545c.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L21tbW1tbW1tbW16_size_16_color_FFFFFF_t_70 2]: /images/20230209/c6066424c947405a920a55cf813a9bbc.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L21tbW1tbW1tbW16_size_16_color_FFFFFF_t_70 3]: /images/20230209/26d45fa9c6664d29a61162f2594055a1.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L21tbW1tbW1tbW16_size_16_color_FFFFFF_t_70 4]: /images/20230209/e9b33ca7220f460eafbfae64932c3305.png