使用jsp实现登录页面，增删改查页面，mysql数据库。

package dbservlet; import java.io.IOException; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.util.ArrayList; import java.util.List; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import bean.Page; import bean.StudentInfo; public class AllServlet extends HttpServlet { /** * */ private static final long serialVersionUID = 1L; // doPost方法 public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("UTF-8"); response.setCharacterEncoding("UTF-8"); String methodName = request.getParameter("methodName"); int method = Integer.parseInt(methodName); try { switch (method) { case 0: insert(request, response); case 1: difpage(request, response); break; case 2: delete(request, response); break; case 3: update(request, response); break; case 4: update1(request, response); break; case 5: dispatch(request, response); break; } } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } // doGet方法 public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } // 数据库连接方法 public Connection connect() throws ClassNotFoundException, SQLException { Connection conn = null; Class.forName("com.mysql.jdbc.Driver"); String url = "jdbc:mysql://localhost:3306/student"; String user = "root"; String password = "123456"; conn = DriverManager.getConnection(url, user, password); return conn; } // 关闭数据库资源 public void close(Statement stat, Connection conn) throws SQLException { if (stat != null) { stat.close(); } if (conn != null) { conn.close(); } } // 插入方法 public void insert(HttpServletRequest request, HttpServletResponse response) throws ClassNotFoundException, SQLException { Connection conn = null; Statement stat = null; String id = request.getParameter("id"); String name = request.getParameter("name"); String age = request.getParameter("age"); String gender = request.getParameter("gender"); String major = request.getParameter("major"); conn = connect(); stat = conn.createStatement(); stat.execute("insert into student(id,name,age,gender,major) values(" + id + ",'" + name + "'," + age + ",'" + gender + "','" + major + "')"); close(stat, conn); } // 查询方法 public ArrayList<StudentInfo> select(String id, String name) throws ClassNotFoundException, SQLException { Connection conn = null; Statement stat = null; ResultSet rs = null; conn = connect(); stat = conn.createStatement(); ArrayList<StudentInfo> result = new ArrayList<StudentInfo>(); if (id == "" && name == "") { rs = stat.executeQuery("select * from student"); } if (id != "" && name == "") { rs = stat.executeQuery("select * from student where id=" + id + ""); } if (id == "" && name != "") { rs = stat.executeQuery("select * from student where name='" + name + "'"); } if (id != "" && name != "") { rs = stat.executeQuery("select * from student where id=" + id + " and name='" + name + "'"); } while (rs.next()) { StudentInfo st = new StudentInfo(); st.setId(rs.getInt("id")); st.setName(rs.getString("name")); st.setAge(rs.getInt("age")); st.setGender(rs.getString("gender")); st.setMajor(rs.getString("major")); result.add(st); } if (rs != null) { rs.close(); } close(stat, conn); return result; } // 条件查询跳转 public void dispatch(HttpServletRequest request, HttpServletResponse response) throws ClassNotFoundException, SQLException, ServletException, IOException { String id5 = request.getParameter("id"); String name5 = request.getParameter("name"); if (select(id5, name5).isEmpty()) { request.getRequestDispatcher("selectnothing.jsp").forward(request, response); } else { request.setAttribute("result", select(id5, name5)); request.getRequestDispatcher("idnameselect.jsp").forward(request, response); } } // 设置分页相关参数方法 public Page setpage(HttpServletRequest request, HttpServletResponse response) throws ClassNotFoundException, SQLException { String crd = request.getParameter("currentRecord"); // String id=request.getParameter("id"); // String name=request.getParameter("name"); ArrayList<StudentInfo> result = select("", ""); Page pager = new Page(); pager.setTotalRecord(result.size()); pager.setTotalPage(result.size(), pager.getPageSize()); if (crd != null) { int currentRecord = Integer.parseInt(crd); pager.setCurrentRecord(currentRecord); pager.setCurrentPage(currentRecord, pager.getPageSize()); } return pager; } // 获得分页显示的子集 public void difpage(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException, ClassNotFoundException, SQLException { // String id=request.getParameter("id"); // String name=request.getParameter("name"); ArrayList<StudentInfo> result = select("", ""); Page pager = new Page(); pager = setpage(request, response); List<StudentInfo> subResult = null; int currentRecord = pager.getCurrentRecord(); if (currentRecord == 0) { if (pager.getTotalRecord() < 8) { subResult = (List<StudentInfo>) result.subList(0, pager.getTotalRecord()); } else { subResult = (List<StudentInfo>) result.subList(0, pager.getPageSize()); } } else if (pager.getCurrentRecord() + pager.getPageSize() < result .size()) { subResult = (List<StudentInfo>) result.subList( pager.getCurrentRecord(), pager.getCurrentRecord() + pager.getPageSize()); } else { subResult = (List<StudentInfo>) result.subList( pager.getCurrentRecord(), result.size()); } request.setAttribute("pager", pager); request.setAttribute("subResult", subResult); request.getRequestDispatcher("layout.jsp").forward(request, response); } // 信息删除方法 public void delete(HttpServletRequest request, HttpServletResponse response) throws ClassNotFoundException, SQLException, ServletException, IOException { Connection conn = null; Statement stat = null; conn = connect(); stat = conn.createStatement(); String id2 = request.getParameter("id"); stat.execute("delete from student where id=" + id2 + ""); request.getRequestDispatcher("delete.jsp").forward(request, response); } // 信息修改方法 public void update1(HttpServletRequest request, HttpServletResponse response) throws ClassNotFoundException, SQLException, ServletException, IOException { String id4 = request.getParameter("id"); request.setAttribute("result", select(id4, "")); request.getRequestDispatcher("update1.jsp").forward(request, response); } public void update(HttpServletRequest request, HttpServletResponse response) throws ClassNotFoundException, SQLException, ServletException, IOException { Connection conn = null; Statement stat = null; String id3 = request.getParameter("id"); String name3 = request.getParameter("name"); String age3 = request.getParameter("age"); String gender3 = request.getParameter("gender"); String major3 = request.getParameter("major"); conn = connect(); stat = conn.createStatement(); stat.execute("update student set id=" + id3 + ",name='" + name3 + "',age=" + age3 + ",gender='" +