代码在修改更新上有一些缺陷，应该先把相应的要修改的部分查询显示显示出来再进行修改。其实完成增删改查的原理与登录注册是一样的。 1.首先建student类。 public class Studentmodel {private int id;private String name;private String grade;private Str

代码在修改更新上有一些缺陷，应该先把相应的要修改的部分查询显示显示出来再进行修改。其实完成增删改查的原理与登录注册是一样的。

1.首先建student类。

public class Studentmodel {		private int id;	private String name;	private String grade;	private String gender;	private int age;	private String address;		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 getGrade() {		return grade;	}	public void setGrade(String grade) {		this.grade = grade;	}	public String getGender() {		return gender;	}	public void setGender(String gender) {		this.gender = gender;	}	public int getAge() {		return age;	}	public void setAge(int age) {		this.age = age;	}	public String getAddress() {		return address;	}	public void setAddress(String address) {		this.address = address;	}}

2.

1)建接口类。

package cn.edu.hpu.service;import cn.edu.hpu.model.Studentmodel;public interface Student {	public boolean addStu(Studentmodel studentmodel);    public boolean delStu(int id);    public boolean updStu(int id,Studentmodel studentmodel);    public Studentmodel selStu(int id);} 

2)接口类的实现

package cn.edu.hpu.service;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import com.mysql.jdbc.Connection;import cn.edu.hpu.model.Studentmodel;import cn.edu.hpu.util.Util;public class StudentImpl implements Student {	@Override	public boolean addStu(Studentmodel studentmodel) {				boolean flag=false;		String sql="insert into student1(id,name,grade,gender,age,address) value(?,?,?,?,?,?)";		Connection conn=Util.getConnection();		PreparedStatement pst;		try {			pst = conn.prepareStatement(sql);			pst.setInt(1, studentmodel.getId());			pst.setString(2, studentmodel.getName());			pst.setString(3, studentmodel.getGrade());			pst.setString(4, studentmodel.getGender());			pst.setInt(5, studentmodel.getAge());			pst.setString(6, studentmodel.getAddress());			pst.executeUpdate();			flag=true;		} catch (SQLException e) {			// TODO Auto-generated catch block			e.printStackTrace();		}		return flag;	}	@Override	public boolean delStu(int id) {				boolean flag=false;		String sql="delete from student1 where id="+id;		Connection conn=Util.getConnection();		try {			PreparedStatement pst=conn.prepareStatement(sql);			pst.executeUpdate();			flag=true;		} catch (SQLException e) {			// TODO Auto-generated catch block			e.printStackTrace();		}		return flag;	}	@Override	public boolean updStu(int id, Studentmodel studentmodel) {				boolean flag=false;		String sql="update student1 set id=?,name=?,grade=?,gender=?,age=?,address=? where id="+id;		Connection conn=Util.getConnection();		PreparedStatement pst;		try {			pst = conn.prepareStatement(sql);			pst.setInt(1, studentmodel.getId());			pst.setString(2, studentmodel.getName());			pst.setString(3,studentmodel.getGrade());			pst.setString(4, studentmodel.getGender());			pst.setInt(5, studentmodel.getAge());			pst.setString(6, studentmodel.getAddress());			pst.executeUpdate();			flag=true;		} catch (SQLException e) {			// TODO Auto-generated catch block			e.printStackTrace();		}		return flag;	}	@Override	public Studentmodel selStu(int id) {		Studentmodel studentmodel=new Studentmodel();		String sql="select * from student1 where id=?";		Connection conn=Util.getConnection();		try {			PreparedStatement pst=conn.prepareStatement(sql);			pst.setInt(1,id);			ResultSet rs=pst.executeQuery();			while(rs.next()){				//遍历结果集				studentmodel.setId(rs.getInt("id"));				studentmodel.setName(rs.getString("name"));				studentmodel.setGrade(rs.getString("grade"));				studentmodel.setGender(rs.getString("gender"));				studentmodel.setAge(rs.getInt("age"));				studentmodel.setAddress(rs.getString("address"));			}		} catch (SQLException e) {			// TODO Auto-generated catch block			e.printStackTrace();		}		// TODO Auto-generated method stub		return studentmodel;	}}

3.建立每个接口方法的servlet。

1）添加的servlet

package cn.edu.hpu.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import cn.edu.hpu.model.Studentmodel;import cn.edu.hpu.service.Student;import cn.edu.hpu.service.StudentImpl;public class tianjia extends HttpServlet {	/**	 * 	 */	private static final long serialVersionUID = 1L;	public void doGet(HttpServletRequest request, HttpServletResponse response)			throws ServletException, IOException {		doPost(request,response);	}	public void doPost(HttpServletRequest request, HttpServletResponse response)			throws ServletException, IOException {				request.setCharacterEncoding("utf-8");		int Id = Integer.parseInt(request.getParameter("id"));        String Name=request.getParameter("name");        String Grade=request.getParameter("grade");        String Gender=request.getParameter("gender");        int Age=Integer.parseInt(request.getParameter("age"));        String Address=request.getParameter("address");                Studentmodel studentmodel=new Studentmodel();        studentmodel.setId(Id);        studentmodel.setName(Name);        studentmodel.setGrade(Grade);        studentmodel.setGender(Gender);        studentmodel.setAge(Age);        studentmodel.setAddress(Address);                Student stu=new StudentImpl();        boolean flag=stu.addStu(studentmodel);        if(flag){        	StudentDaoServlet s=new StudentDaoServlet();        	s.doPost(request, response);        }	}}

2）删除的servlet。

package cn.edu.hpu.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import cn.edu.hpu.model.Studentmodel;import cn.edu.hpu.service.Student;import cn.edu.hpu.service.StudentImpl;public class shanchu extends HttpServlet {	/**	 * 	 */	private static final long serialVersionUID = 1L;	public void doGet(HttpServletRequest request, HttpServletResponse response)			throws ServletException, IOException {        doPost(request,response);	}		public void doPost(HttpServletRequest request, HttpServletResponse response)			throws ServletException, IOException {				request.setCharacterEncoding("UTF-8");		int Id=Integer.parseInt(request.getParameter("id"));      		Studentmodel studentmodel=new Studentmodel();		studentmodel.setId(Id);				Student stu=new StudentImpl();		boolean flag=stu.delStu(Id);		if(flag){			StudentDaoServlet s=new StudentDaoServlet();			s.doPost(request, response);		}	}}

3）更新的servlet。

package cn.edu.hpu.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import cn.edu.hpu.model.Studentmodel;import cn.edu.hpu.service.Student;import cn.edu.hpu.service.StudentImpl;public class gengxin extends HttpServlet {		/**	 * 	 */	private static final long serialVersionUID = 1L;	public void doGet(HttpServletRequest request, HttpServletResponse response)			throws ServletException, IOException {          doPost(request,response);	}	public void doPost(HttpServletRequest request, HttpServletResponse response)			throws ServletException, IOException {            request.setCharacterEncoding("UTF-8");            int Id=Integer.parseInt(request.getParameter("id"));            String Name=request.getParameter("name");            String Grade=request.getParameter("grade");            String Gender=request.getParameter("gender");            int Age=Integer.parseInt(request.getParameter("age"));            String Address=request.getParameter("address");                        Studentmodel studentmodel=new Studentmodel();            studentmodel.setId(Id);            studentmodel.setName(Name);            studentmodel.setGrade(Grade);            studentmodel.setGender(Gender);            st本文来源gao.dai.ma.com搞@代*码#网udentmodel.setAge(Age);            studentmodel.setAddress(Address);                        Student stu=new StudentImpl();            boolean flag=stu.updStu(Id, studentmodel);            if(flag){            	StudentDaoServlet s=new StudentDaoServlet();            	s.doPost(request, response);            }             }}

4）查询的servlet。

以上即完成了增删改查的操作。

4. 建jsp页面。这是登录注册完成后跳转到的页面。有添加，删除，修改，查询的超链接，点击后跳转到相应页面可以进行相应的操作。

<body>

至此完成了增删改查的相应操作。

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