entity层和DBUtil层同增的操作，今天是修改操作（代码部分加上之前的）：
dao层：
1 package dao;
2
3 import java.sql.Connection;
4 import java.sql.PreparedStatement;
5 import java.sql.ResultSet;
6 import java.sql.SQLException;
7 import java.sql.Statement;
8 import java.util.ArrayList;
9 import java.util.List;
10
11 import DBUtil.DBUtil;
12 import entity.Book;
13 import entity.Lendbook;
14
15
16
17
18 public class Dao {
19 //根据书的姓名查找
20 public Book getbyname(String bname) {
21 String sql = "select * from Book where bname ='" + bname + "'";
22 Connection conn = DBUtil.getConn();
23 Statement state = null;
24 ResultSet rs = null;
25 Book b = null;
26
27 try {
28 state = conn.createStatement();
29 rs = state.executeQuery(sql);
30 while (rs.next()) {
31 int id = rs.getInt("id");
32 String bianhao = rs.getString("bianhao");
33 String bname2 = rs.getString("bname");
34 String wname = rs.getString("wname");
35 String bhome=rs.getString("bhome");
36 int num = rs.getInt("num");
37 b = new Book(id,bianhao,bname2,wname,bhome,num);
38 }
39 } catch (Exception e) {
40 e.printStackTrace();
41 } finally {
42 DBUtil.close(rs, state, conn);
43 }
44
45 return b;
46 }
47
48 //添加新书信息
49 public boolean addBook(Book stu) {
50 Connection conn = DBUtil.getConn();
51 PreparedStatement pstmt = null;
52 boolean f = false;
53 int a = 0;
54 try {
55 String sql = "insert into Book(bianhao,bname,wname,bhome,num) value(?,?,?,?,?)";
56 pstmt = conn.prepareStatement(sql);
57 pstmt.setString(1, stu.getBianhao());
58 pstmt.setString(2, stu.getBname());
59 pstmt.setString(3, stu.getWname());
60 pstmt.setString(4, stu.getBhome());
61 pstmt.setLong(5, stu.getNum());
62 a = pstmt.executeUpdate();
63 } catch (SQLException e) {
64 e.printStackTrace();
65 } finally {
66 DBUtil.close(pstmt, conn);
67 }
68 if (a > 0)
69 f = true;
70
71 return f;
72 }
73 //删除图书信息，根据书名删除
74 public boolean deleteBook(String bname)
75 {
76 String sql="delete from Book where bname='" + bname + "'";
77 Connection conn = DBUtil.getConn();
78 Statement state = null;
79 int a = 0;
80 boolean f = false;
81 try {
82 state = conn.createStatement();
83 a = state.executeUpdate(sql);
84 } catch (SQLException e) {
85 e.printStackTrace();
86 } finally {
87 DBUtil.close(state, conn);
88 }
89
90 if (a > 0) {
91 f = true;
92 }
93 return f;
94 }
95
96 //更新图书信息，获取的是书的姓名
97 public boolean updateBook(Book stu,String old_bname) {
98 String sql = "update Book set bianhao='" + stu.getBianhao() + "', bname='" + stu.getBname() + "', wname='"
99 + stu.getWname() + "',bhome='" + stu.getBhome() + "',num='" + stu.getNum() + "'where bname='"+old_bname+"'";
100 Connection conn = DBUtil.getConn();
101 Statement state = null;
102 boolean f = false;
103 int a = 0;
104 try {
105 state = conn.createStatement();
106 System.out.println("修改成功");
107 a = state.executeUpdate(sql);
108 System.out.println(a);
109 } catch (SQLException e) {
110 e.printStackTrace();
111 } finally {
112 DBUtil.close(state, conn);
113 }
114
115 if (a > 0) {
116 f = true;
117 }
118
119 System.out.println(f);
120 return f;
121 }
122 //浏览图书信息
123 public List<Book> liulanbook() {
124 String sql = "select * from Book";
125 List<Book> list = new ArrayList<>();
126 Connection conn = DBUtil.getConn();
127 Statement state = null;
128 ResultSet rs = null;
129
130 try {
131 state = conn.createStatement();
132 rs = state.executeQuery(sql);
133 Book bean = null;
134 while (rs.next()) {
135 int id = rs.getInt("id");
136 String bianhao = rs.getString("bianhao");
137 String bname = rs.getString("bname");
138 String wname = rs.getString("wname");
139 String bhome=rs.getString("bhome");
140 int num = rs.getInt("num");
141 bean = new Book(id,bianhao,bname,wname,bhome,num);
142 list.add(bean);
143 }
144 } catch (SQLException e) {
145 e.printStackTrace();
146 } finally {
147 DBUtil.close(rs, state, conn);
148 }
149
150 return list;
151 }
152
153
154 }
servlet层：
1 package servlet;
2
3 import java.io.IOException;
4 import java.util.List;
5
6 import javax.servlet.ServletException;
7 import javax.servlet.annotation.WebServlet;
8 import javax.servlet.http.HttpServlet;
9 import javax.servlet.http.HttpServletRequest;
10 import javax.servlet.http.HttpServletResponse;
11
12 import dao.Dao;
13 import entity.Book;
14
15 @WebServlet("/Servlet")
16 public class Servlet extends HttpServlet {
17 private static final long serialVersionUID = 1L;
18 Dao dao = new Dao();
19
20 protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
21 req.setCharacterEncoding("utf-8");
22 String method = req.getParameter("method");
23 if ("addBook".equals(method)) {
24 addBook(req, resp);
25 } else if ("liulanbook".equals(method)) {
26 liulanbook(req, resp);
27 } else if ("getbyname".equals(method)) {
28 getbyname(req, resp);
29 } else if ("deleteBook".equals(method)) {
30 deleteBook(req, resp);
31 }else if("updateBook".equals(method)) {
32 updateBook(req,resp);
33 }
34 }
35
36 private void deleteBook(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException {
37 // TODO 自动生成的方法存根
38 req.setCharacterEncoding("utf-8");
39 String bname = req.getParameter("bname");
40 if (dao.deleteBook(bname)) {
41 req.setAttribute("message", "删除成功");
42 req.getRequestDispatcher("Servlet?method=liulanbook2").forward(req, resp);
43 } else {
44 req.setAttribute("message", "删除失败");
45 req.getRequestDispatcher("Servlet?method=liulanbook2").forward(req, resp);
46 }
47 }
48
49 private void addBook(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
50 req.setCharacterEncoding("utf-8");
51 String bianhao = req.getParameter("bianhao");
52 String bname = req.getParameter("bname");
53 String wname = req.getParameter("wname");
54 String bhome = req.getParameter("bhome");
55 int num = Integer.parseInt(req.getParameter("num"));
56 Book book = new Book(bianhao, bname, wname, bhome, num);
57 if (dao.addBook(book)) {
58 req.setAttribute("book", book);
59 req.setAttribute("message", "添加成功");
60 req.getRequestDispatcher("addBook.jsp").forward(req, resp);
61 } else {
62 req.setAttribute("message", "书籍信息重复，请重新输入");
63 req.getRequestDispatcher("addBook.jsp").forward(req, resp);
64 }
65 }
66
67
68 private void getbyname(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
69 req.setCharacterEncoding("utf-8");
70 String bname = req.getParameter("bname");
71 Book b=new Book();
72 b.setBname(bname);
73 b= dao.getbyname(bname);
74 if(b==null)
75 {
76 req.setAttribute("message", "未找到该书籍");
77 req.getRequestDispatcher("xiugaiBook.jsp").forward(req, resp);
78 }
79 else
80 {
81 req.setAttribute("b", b);
82 req.getRequestDispatcher("xiugai2.jsp").forward(req,resp);
83 }
84 }
85 private void liulanbook(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException {
86 req.setCharacterEncoding("utf-8");
87
88 List<Book> tens = dao.liulanbook();
89 req.setAttribute("tens", tens);
90 req.getRequestDispatcher("list.jsp").forward(req, resp);
91 }
92
93 private void updateBook(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
94 req.setCharacterEncoding("utf-8");
95 String old_bname = req.getParameter("old_bname");
96 String bianhao=req.getParameter("bianhao");
97 String bname = req.getParameter("bname");
98 String wname= req.getParameter("wname");
99 String bhome = req.getParameter("bhome");
100 int num = Integer.parseInt(req.getParameter("num"));
101 Book b = new Book(bianhao, bname, wname, bhome, num);
102 if (dao.updateBook(b,old_bname)) {
103 req.setAttribute("message", "修改成功");
104 req.getRequestDispatcher("Servlet?method=liulanbook2").forward(req, resp);
105 }else {
106 req.setAttribute("message", "修改失败");
107 req.getRequestDispatcher("Servlet?method=liulanbook2").forward(req, resp);
108 }
109 }
110 }
xiugai2.jsp:
1 <%@ page language="java" contentType="text/html; charset=UTF-8"
2 pageEncoding="UTF-8"%>
3 <%@ page import="entity.*" %>
4 <!DOCTYPE html>
5 <html>
6 <head>
7 <meta charset="UTF-8">
8 <title>修改学生信息</title>
9 <script>
10 </script>
11 </head>
12 <body>
13 <%
14 Object message = request.getAttribute("message");
15 if(message!=null && !"".equals(message)){
16
17 %>
18 <script type="text/javascript">
19 alert("<%=request.getAttribute("message")%>");
20 </script>
21 <%} %>
22 <%
23 Book b=(Book)request.getAttribute("b");
24 %>
25 <table align="center" border="0px" cellpadding="10px" cellspacing="10px">
26 <form action="Servlet?method=updateBook" method="post" onsubmit="return check()">
27 <tr>
28 <td><a href="guanli.jsp">返回菜单</a></td>
29 </tr>
30 <input type="hidden" name="old_bname" value="<%=b.getBname()%>"/>
31 <tr>
32 <td>图书编号:</td>
33 <td><input type="text" name="bianhao" id="bianhao" value="<%=b.getBianhao()%>"/></td>
34 </tr>
35 <tr>
36 <td>书名：</td>
37 <td><input type="text" name="bname" id="bname" value="<%=b.getBname()%>"></td>
38 </tr>
39
40 <tr>
41 <td>作者名：</td>
42 <td><input type="text" name="wname" id="wname" value="<%=b.getWname()%>"></td>
43 </tr>
44 <tr>
45 <tr>
46 <td>出版社名称：</td>
47 <td><input type="text" name="bhome" id="bhome" value="<%=b.getBhome()%>"></td>
48 </tr>
49 <tr>
50 <tr>
51 <td>可借阅数量：</td>
52 <td><input type="text" name="num" id="num" value="<%=b.getNum()%>"></td>
53 </tr>
54 <tr>
55 <tr align="center">
56 <th colspan="2">
57 <input type="submit" value="修改">
58 </th>
59 </tr>
60 </form>
61 </table>
62 </body>
63 </html>
在list页面中，删除功能直接调用函数就可以实现
<td><a href="Servlet?method=getbyname&bname=${item.bname }">修改</a>