jsp+servlet简单图书馆管理系统

package com.servlet; import java.io.IOException; import java.io.PrintWriter; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; 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 javax.servlet.http.HttpSession; import com.JDBC.JDBC_connect; @WebServlet("/BorrowBook") public class BorrowBook extends HttpServlet { private static final long serialVersionUID = 1L; public BorrowBook() { super(); // TODO Auto-generated constructor stub } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("utf-8"); response.setContentType("text/html;charset=utf-8"); PrintWriter out = response.getWriter(); String bookname = request.getParameter("bookname"); String writer = request.getParameter("writer"); HttpSession session = request.getSession(); String readerName = (String) session.getAttribute("readerName"); String reader_No = (String) session.getAttribute("userid"); Long readerNo = Long.parseLong(reader_No); Connection con = null; con = JDBC_connect.getConnnection(); java.util.Date date = new java.util.Date(); java.sql.Date time = new java.sql.Date(date.getTime()); if (con != null) { try { String sql1 = "select * from book where bookName='" + bookname + "' and writer='" + writer + "' and count>0 "; Statement stmt1 = con.createStatement(); ResultSet rs1 = stmt1.executeQuery(sql1); if (rs1.next()) { int bookNo = rs1.getInt("bookNo"); int count = rs1.getInt("count"); String sql3 = "select * from borrow where bookNo =" + bookNo + " and readerNo =" + readerNo+" and isDel = 0"; //Statement stmt3 = con.createStatement(); ResultSet rs3 = stmt1.executeQuery(sql3); if (rs3.next()) { out.print("<script>alert('您已经借过这本书了！');history.go(-1);</script>"); } else { String sql = "insert into borrow (bookNo,bookName,writer,readerNo,readerName,borrowdata) values(?,?,?,?,?,?)"; PreparedStatement stmt = con.prepareStatement(sql); stmt.setInt(1, bookNo); stmt.setString(2,bookname); stmt.setString(3, writer); stmt.setLong(4, readerNo); stmt.setString(5, readerName); stmt.setDate(6, time); stmt.executeUpdate(); count = count - 1; String sql2 = "update book set count=" + count + " where bookNo=" + bookNo; Statement stmt2 = con.createStatement(); int rs2 = stmt2.executeUpdate(sql2); if (rs2 > 0) out.print("<script>alert('借阅成功！');history.go(-2);</script>"); else out.print("<script>alert('借阅失败！');history.go(-1);</script>"); } } else out.print("<script>alert('查无此书！');history.go(-1);</script>"); } catch (SQLException e) { e.printStackTrace(); } } doGet(request, response); } }