Servlet中的CRUD操作示例图解

对于任何项目开发而言, CRUD(创建, 读取, 更新和删除)应用程序都是最重要的应用程序。在Servlet中, 我们可以轻松创建CRUD应用程序。
Servlet CRUD示例使用序列使用自动递增的ID在Oracle数据库中创建” user905″ 表。其中有5个字段：ID, 名称, 密码, 电子邮件和国家。

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档案：index.html

< !DOCTYPE html> < html> < head> < meta charset="ISO-8859-1"> < title> Insert title here< /title> < /head> < body> < h1> Add New Employee< /h1> < form action="SaveServlet" method="post"> < table> < tr> < td> Name:< /td> < td> < input type="text" name="name"/> < /td> < /tr> < tr> < td> Password:< /td> < td> < input type="password" name="password"/> < /td> < /tr> < tr> < td> Email:< /td> < td> < input type="email" name="email"/> < /td> < /tr> < tr> < td> Country:< /td> < td> < select name="country" style="width:150px"> < option> India< /option> < option> USA< /option> < option> UK< /option> < option> Other< /option> < /select> < /td> < /tr> < tr> < td colspan="2"> < input type="submit" value="http://www.srcmini.com/Save Employee"/> < /td> < /tr> < /table> < /form> < br/> < a href="http://www.srcmini.com/ViewServlet"> view employees< /a> < /body> < /html>

档案：Emp.java

public class Emp { private int id; private String name, password, email, country; 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 getPassword() { return password; } public void setPassword(String password) { this.password = password; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public String getCountry() { return country; } public void setCountry(String country) { this.country = country; }}

档案：EmpDao.java

import java.util.*; import java.sql.*; public class EmpDao { public static Connection getConnection(){ Connection con=null; try{ Class.forName("oracle.jdbc.driver.OracleDriver"); con=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe", "system", "oracle"); }catch(Exception e){System.out.println(e); } return con; } public static int save(Emp e){ int status=0; try{ Connection con=EmpDao.getConnection(); PreparedStatement ps=con.prepareStatement( "insert into user905(name, password, email, country) values (?, ?, ?, ?)"); ps.setString(1, e.getName()); ps.setString(2, e.getPassword()); ps.setString(3, e.getEmail()); ps.setString(4, e.getCountry()); status=ps.executeUpdate(); con.close(); }catch(Exception ex){ex.printStackTrace(); }return status; } public static int update(Emp e){ int status=0; try{ Connection con=EmpDao.getConnection(); PreparedStatement ps=con.prepareStatement( "update user905 set name=?, password=?, email=?, country=? where id=?"); ps.setString(1, e.getName()); ps.setString(2, e.getPassword()); ps.setString(3, e.getEmail()); ps.setString(4, e.getCountry()); ps.setInt(5, e.getId()); status=ps.executeUpdate(); con.close(); }catch(Exception ex){ex.printStackTrace(); }return status; } public static int delete(int id){ int status=0; try{ Connection con=EmpDao.getConnection(); PreparedStatement ps=con.prepareStatement("delete from user905 where id=?"); ps.setInt(1, id); status=ps.executeUpdate(); con.close(); }catch(Exception e){e.printStackTrace(); }return status; } public static Emp getEmployeeById(int id){ Emp e=new Emp(); try{ Connection con=EmpDao.getConnection(); PreparedStatement ps=con.prepareStatement("select * from user905 where id=?"); ps.setInt(1, id); ResultSet rs=ps.executeQuery(); if(rs.next()){ e.setId(rs.getInt(1)); e.setName(rs.getString(2)); e.setPassword(rs.getString(3)); e.setEmail(rs.getString(4)); e.setCountry(rs.getString(5)); } con.close(); }catch(Exception ex){ex.printStackTrace(); }return e; } public static List< Emp> getAllEmployees(){ List< Emp> list=new ArrayList< Emp> (); try{ Connection con=EmpDao.getConnection(); PreparedStatement ps=con.prepareStatement("select * from user905"); ResultSet rs=ps.executeQuery(); while(rs.next()){ Emp e=new Emp(); e.setId(rs.getInt(1)); e.setName(rs.getString(2)); e.setPassword(rs.getString(3)); e.setEmail(rs.getString(4)); e.setCountry(rs.getString(5)); list.add(e); } con.close(); }catch(Exception e){e.printStackTrace(); }return list; } }

文件：SaveServlet.java

import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @WebServlet("/SaveServlet") public class SaveServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); PrintWriter out=response.getWriter(); String name=request.getParameter("name"); String password=request.getParameter("password"); String email=request.getParameter("email"); String country=request.getParameter("country"); Emp e=new Emp(); e.setName(name); e.setPassword(password); e.setEmail(email); e.setCountry(country); int status=EmpDao.save(e); if(status> 0){ out.print("< p> Record saved successfully!< /p> "); request.getRequestDispatcher("index.html").include(request, response); }else{ out.println("Sorry! unable to save record"); }out.close(); }}

文件：EditServlet.java

import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @WebServlet("/EditServlet") public class EditServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); PrintWriter out=response.getWriter(); out.println("< h1> Update Employee< /h1> "); String sid=request.getParameter("id"); int id=Integer.parseInt(sid); Emp e=EmpDao.getEmployeeById(id); out.print("< form action='EditServlet2' method='post'> "); out.print("< table> "); out.print("< tr> < td> < /td> < td> < input type='hidden' name='id' value='"+e.getId()+"'/> < /td> < /tr> "); out.print("< tr> < td> Name:< /td> < td> < input type='text' name='name' value='"+e.getName()+"'/> < /td> < /tr> "); out.print("< tr> < td> Password:< /td> < td> < input type='password' name='password' value='"+e.getPassword()+"'/> < /td> < /tr> "); out.print("< tr> < td> Email:< /td> < td> < input type='email' name='email' value='"+e.getEmail()+"'/> < /td> < /tr> "); out.print("< tr> < td> Country:< /td> < td> "); out.print("< select name='country' style='width:150px'> "); out.print("< option> India< /option> "); out.print("< option> USA< /option> "); out.print("< option> UK< /option> "); out.print("< option> Other< /option> "); out.print("< /select> "); out.print("< /td> < /tr> "); out.print("< tr> < td colspan='2'> < input type='submit' value='http://www.srcmini.com/Edit & Save'/> < /td> < /tr> "); out.print("< /table> "); out.print("< /form> "); out.close(); } }

文件：EditServlet2.java

import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @WebServlet("/EditServlet2") public class EditServlet2 extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); PrintWriter out=response.getWriter(); String sid=request.getParameter("id"); int id=Integer.parseInt(sid); String name=request.getParameter("name"); String password=request.getParameter("password"); String email=request.getParameter("email"); String country=request.getParameter("country"); Emp e=new Emp(); e.setId(id); e.setName(name); e.setPassword(password); e.setEmail(email); e.setCountry(country); int status=EmpDao.update(e); if(status> 0){ response.sendRedirect("ViewServlet"); }else{ out.println("Sorry! unable to update record"); }out.close(); }}

文件：DeleteServlet.java

import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @WebServlet("/DeleteServlet") public class DeleteServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String sid=request.getParameter("id"); int id=Integer.parseInt(sid); EmpDao.delete(id); response.sendRedirect("ViewServlet"); } }

文件：ViewServlet.java

import java.io.IOException; import java.io.PrintWriter; import java.util.List; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @WebServlet("/ViewServlet") public class ViewServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); PrintWriter out=response.getWriter(); out.println("< a href='http://www.srcmini.com/index.html'> Add New Employee< /a> "); out.println("< h1> Employees List< /h1> "); List< Emp> list=EmpDao.getAllEmployees(); out.print("< table border='1' width='100%'"); out.print("< tr> < th> Id< /th> < th> Name< /th> < th> Password< /th> < th> Email< /th> < th> Country< /th> < th> Edit< /th> < th> Delete< /th> < /tr> "); for(Emp e:list){ out.print("< tr> < td> "+e.getId()+"< /td> < td> "+e.getName()+"< /td> < td> "+e.getPassword()+"< /td> < td> "+e.getEmail()+"< /td> < td> "+e.getCountry()+"< /td> < td> < a href='http://www.srcmini.com/EditServlet?id="+e.getId()+"'> edit< /a> < /td> < td> < a href='http://www.srcmini.com/DeleteServlet?id="+e.getId()+"'> delete< /a> < /td> < /tr> "); } out.print("< /table> "); out.close(); } }

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