java:JSP(JSPWeb.xml的配置,动态和静态导入JSP文件,重定项和请求转发,使用JSP实现数据库的增删改查实例)
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1.JSP的配置:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/"; %> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="<%=basePath%>"> <title>My JSP ‘register.jsp‘ starting page</title> </head> <body> <pre> JSP:java servlet page jsp也是一个servlet:要继承HttpServlet--->service方法 jsp当被访问的时候,tomcat会自动把它编译成Java class,会生成一个遵循某个命名规则的clas和Java文件(以login.jsp为例,首先会把.转换为_,然后进行连接--->login_jsp.java/class,这里的命名规则并不遵循Java的驼峰命名规则) 这个class继承了--->org.apache.jasper.runtime.HttpJspBase--->拥有_jspService org.apache.jasper.runtime.HttpJspBase继承了---->HttpServlet--->重写了service方法---->调用了这个class的_jspService方法 也就是相当于tomcat把jsp文件生成Java类继承了httpservlet 所以说jsp也就是一个servlet ---->必须要配置 <servlet> <servlet-name></servlet-name> <servlet-class></servlet-class> </servlet> <servlet-mapping> <servlet-name></servlet-name> <url-pattern></url-pattern> </servlet-mapping> jsp在tomcat的conf文件下web.xml进行配置 <servlet> <servlet-name>jsp</servlet-name> <servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class> <init-param> <param-name>fork</param-name> <param-value>false</param-value> </init-param> <init-param> <param-name>xpoweredBy</param-name> <param-value>false</param-value> </init-param> <load-on-startup>3</load-on-startup> </servlet> <servlet-mapping> <servlet-name>jsp</servlet-name> <url-pattern>*.jsp</url-pattern> <url-pattern>*.jspx</url-pattern> </servlet-mapping> 所以org.apache.jasper.servlet.JspServlet来处理以jsp为结尾的路径 JspServlet-->就是一个servlet--->重写了service方法--->把jsp(warrper)文件转换为class文件 </pre> </body> </html>
2.动态导入和静态导入JSP文件:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%-- errorPage只能保护运行时异常(404,405,401),不能保护检查时异常(500,600) --%> <%@ page isErrorPage="true" %><%-- 标记本页面是否为错误页面,提供后来人观看代码 --%> <%@ page errorPage="error.jsp" %> <%-- <%@ page import="cn.zzsxt.lee.servlet.*" %> --%><%-- 导入servlet包下的所有Java文件 --%> <%@ page import="cn.zzsxt.lee.servlet.Test" %><%-- 导入Test.java --%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>My JSP ‘login.jsp‘ starting page</title> </head> <body> <pre> jsp即可以写html代码,也可以写Java代码 jsp第一个语法: <!-- 是把两个jsp文件合并成了一个jsp文件 --> <!-- 静态导入:首先会把两个jsp文件合成一个,然后再通过tomcat进行编译,所以只编译了一次,高耦合,所以效率也会提高 --> <%@ include file="top.jsp" %><!-- 无论定位到页面的某一个位置,都能进行导入jsp文件,说白了也就是无论放在任何位置,就把导入的jsp放在哪里 --> <% String name = "zhangsan"; System.out.println(name); // String name2 = "lisi1";// 如果使用<%@ include file="top.jsp" %>导入,报两个变量名不能相同 String name3; /* int x = 1/0; */ //System.out.println(name3); // 运行时异常 // 提示错误信息 // 只有运行时异常,才会被errorpage保护 // 检查时异常 // 直接强行中断正在运行的程序 Test test = new Test(); test.getName(); %> <%=name%> <%=name2%> <%-- <%=x%> --%> </pre> <a href="register.jsp">我是跳转页面用的</a> <!-- 动态导入,会生成两个class文件,从而tomcat编译了两次 --> <jsp:include page="footer.jsp"></jsp:include> </body> </html>
3.重定向和请求转发:
请求转发:
1.request.getRequestDispatcher("需要跳转的路径").forward(request, response);
发送一次请求
地址栏不发生改变
request可以传递参数(能参数共享)
请求转发并不能访问到外部资源(外部的地址)
重定向:
2.response.sendRedirect("需要跳转的路径");
发送两次请求
地址栏发生改变
response不能传递参数(不能参数共享),如果想使用response进行参数传递,就得手动加载,自力更生
重定向可以访问外部资源
请求转发
当需要传递参数的时候
访问内部资源的时候建议使用请求转发(服务器内部之间的调用)
重定向
访问外部资源
比较隐私和保密的地址一般推荐使用重定向
4.使用JSP实现数据库的增删改查实例:
注册:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>My JSP ‘register.jsp‘ starting page</title> </head> <body> <h1>注册页面</h1> <form action="deal_register.jsp" method="post"> 用户名: <input type="text" name="username" /> <br /> 密码: <input type="password" name="pwd" /><br /> 重复密码: <input type="password" name="repwd" /><br /> 手机号: <input type="text" name="phone" /><br /> 爱好: <input type="checkbox" name="hobby" value="football" />足球 <input type="checkbox" name="hobby" value="basketball" />篮球 <input type="checkbox" name="hobby" value="Pingpong" />乒乓球 <br /> 性别: <input type="radio" name="sex" value="male" />男 <input type="radio" name="sex" value="female" />女<br /> <input type="submit" value="提交" /> </form> </body> </html>
处理注册信息存入数据库:
<%@ page language="java" import="java.util.*, java.sql.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>My JSP ‘deal_register.jsp‘ starting page</title> </head> <body> <% // 第一步:获取input的值(也就是用户注册的信息) String username = request.getParameter("username"); String password = request.getParameter("pwd"); String phoneNumber = request.getParameter("phone"); long phone = Long.parseLong(phoneNumber); // String hobby1 = request.getParameter("hobby"); String[] hobby = request.getParameterValues("hobby"); String[] sex = request.getParameterValues("sex"); String hobbys= "";// "football,basketball,pingpong" //hobby.length为3 for(int i = 0;i < hobby.length; i++) { /* if(hobby.length-1 > i) { hobbys +=hobby[i]+",";// 最后一位是, } else { hobbys +=hobby[i]; } */ hobbys +=hobby[i]+","; } hobbys = hobbys.substring(0,hobbys.length()-1); //String sex1 = request.getParameter("sex");// 如果是单选或者多选的话,使用request.getParameter()--->on,规定无论是单选还是多选或者下拉使用request.getParameterValues(); // 第二步:插入数据,id使用UUID //1.导入ojdbc6.jar //2.加载驱动(反射) Class.forName("oracle.jdbc.driver.OracleDriver"); //3.获取连接 Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl","scott","scott"); //4.获取预编译的statement(String sql) String sql = "insert into students (id, stu_name, stu_age, stu_pwd, stu_hobby, stu_sex, stu_phone) values(?,?,?,?,?,?,?)"; PreparedStatement ps = conn.prepareStatement(sql); //5.设置参数ps.setxxxx ps.setString(1,UUID.randomUUID().toString()); ps.setString(2, username); ps.setInt(3, 32); ps.setString(4, password); ps.setString(5, hobbys); ps.setString(6,sex[0]); ps.setLong(7, phone); //6.调用executeUpdate();--->返回值为受影响的行数 int result = ps.executeUpdate(); //7.判断接收的int类型数据,判断是否大于0(大于0成功,小于0失败) if(result > 0) { // 成功 } else { // 失败 } %> </body> </html>
登录:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>My JSP ‘login.jsp‘ starting page</title> </head> <body> <form action="deal_login.jsp" method="post"> 用户名: <input type="text" name="username" /> <br /> 密码: <input type="password" name="pwd" /> <input type="submit" value="提交" /> </form> </body> </html>
处理登录,预跳转至主页处理的界面(查询数据库全部数据):
<%@ page language="java" import="java.util.*, java.sql.*, cn.zzsxt.lee.web.entity.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>My JSP ‘deal_login.jsp‘ starting page</title> </head> <body> <% String username = request.getParameter("username"); String password = request.getParameter("pwd"); //1.加载驱动 Class.forName("oracle.jdbc.driver.OracleDriver"); //2.获取连接 Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl", "scott", "scott"); //3.获取预编译的statement String sql = "select * from teacher where name=? and password=?"; PreparedStatement ps = conn.prepareStatement(sql); //4.设置参数 ps.setString(1, username); ps.setString(2, password); //5.调用executeQuery();-->返回ResultSet ResultSet rs = ps.executeQuery(); //6.遍历结果集 Teacher teacher = new Teacher(); while (rs.next()) { teacher.setId(rs.getInt("id")); teacher.setUsername(rs.getString("name")); teacher.setPassword(rs.getString("password")); teacher.setDescription(rs.getString("description")); } //7.判断是否查询出数据 if (teacher.getUsername() != null && !"".equals(teacher.getUsername())) {// 把“”放在前面,防止空指针 // 成功,跳转主页面的处理页面 // request.getRequestDispatcher("deal_index.jsp").forward(request, response);// 跳转页面 request.getRequestDispatcher("frameset_index.jsp").forward(request, response);// 跳转页面 } else { // 失败,跳转404 //response.sendRedirect("404.jsp"); request.getRequestDispatcher("404.jsp").forward(request, response); } %> </body> </html>
主页处理界面,预跳转至主页:
<%@ page language="java" import="java.util.*, java.sql.*, cn.zzsxt.lee.web.entity.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>My JSP ‘deal_index.jsp‘ starting page</title> </head> <body> <% //1.加载驱动 Class.forName("oracle.jdbc.driver.OracleDriver"); //2.获取连接 Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl", "scott", "scott"); //3.获取预编译的statement String sql = "select * from students"; PreparedStatement ps = conn.prepareStatement(sql); //4.调用executeQuery();-->返回ResultSet ResultSet rs = ps.executeQuery(); //5.遍历结果集 // 定义一个泛型为Student的List集合 List<Student> list = new ArrayList<Student>(); while (rs.next()) { Student student = new Student(); student.setId(rs.getString("id")); student.setStuName(rs.getString("stu_name")); student.setStuPassword(rs.getString("stu_pwd")); list.add(student); } //6.判断list的长度大于0 if(list.size() > 0) { // 成功,跳转到主页面 request.setAttribute("list", list);//--->Map.get("key");--->map.put("name",24);Map<String, Object> request.getRequestDispatcher("index.jsp").forward(request, response); } else { // 失败 } %> </body> </html>
跳转至主页,显示所有数据,及修改和删除的功能:
<%@ page language="java" import="java.util.*, cn.zzsxt.lee.web.entity.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>My JSP ‘index.jsp‘ starting page</title> <script type="text/javascript"> function trueDelete(id) { if (confirm("您确定要删除数据么?")) { window.location.href = "deal_delete.jsp?id=" + id; } } </script> </head> <body> <table border="1"> <thead> <tr> <th>学生编号</th> <th>学生姓名</th> <th>学生密码</th> <th>操作</th> </tr> </thead> <tbody> <% List<Student> listStudent = (List<Student>) request.getAttribute("list"); for (int i = 0; i < listStudent.size(); i++) { listStudent.get(i).getId();// 获取student对象的id %> <%-- jsp的注释 --%> <tr> <!-- 一个tr代表了一行,说白了就是代表一个student对象 --> <td><%=listStudent.get(i).getId()%></td> <!-- <%--<%= %>--%>输出页面 --> <td><%=listStudent.get(i).getStuName()%></td> <td><%=listStudent.get(i).getStuPassword()%></td> <td><a href="javascript:void(0);" onclick="trueDelete(‘<%=listStudent.get(i).getId()%>‘);">删除</a> <a href="select_by_id.jsp?id=<%=listStudent.get(i).getId()%>">修改</a> </td> <!-- 删除功能(主键id删除)需要传递一个参数,同样需要操作数据库,需要deal_delete.jsp进行处理 --> </tr> <% } %> </tbody> </table> </body> </html>
删除功能,删除处理界面,预跳转至主页处理界面(查询删除后还剩的数据,即所有数据)
<%@ page language="java" import="java.util.*, java.sql.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>My JSP ‘deal_delete.jsp‘ starting page</title> </head> <body> <% //所有通过路径传递的参数都要使用request.getParameter() String id = request.getParameter("id"); //1.加载驱动 Class.forName("oracle.jdbc.driver.OracleDriver"); //2.获取连接 Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl", "scott", "scott"); //3.获取预编译的statement String sql = "delete from students where id=?"; PreparedStatement ps = conn.prepareStatement(sql); ps.setString(1, id); int result = ps.executeUpdate(); if (result > 0) { //成功 request.getRequestDispatcher("deal_index.jsp").forward(request, response); } else { // 失败 } %> </body> </html>
修改功能,首先跳转至查询某一行的界面,预跳转至修改界面
<%@ page language="java" import="java.util.*, java.sql.*, cn.zzsxt.lee.web.entity.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>My JSP ‘select_by_id.jsp‘ starting page</title> </head> <body> <% String id = request.getParameter("id"); // 进行查询(通过id) //1.加载驱动 Class.forName("oracle.jdbc.driver.OracleDriver"); //2.获取连接 Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl", "scott", "scott"); //3.获取预编译的statement String sql = "select * from students where id=?"; PreparedStatement ps = conn.prepareStatement(sql); ps.setString(1, id); //4.调用executeQuery();-->返回ResultSet ResultSet rs = ps.executeQuery(); //5.遍历结果集 Student stu = new Student(); while (rs.next()) { stu.setId(rs.getString("id")); stu.setStuName(rs.getString("stu_name")); stu.setStuPassword(rs.getString("stu_pwd")); } if (stu.getId() != null) { request.setAttribute("stu", stu); request.getRequestDispatcher("update.jsp").forward(request, response); } else { // 跳转报错页面 } %> </body> </html>
修改界面,以form表单的形式显示让用户动态修改,预提交至修改处理界面
<%@ page language="java" import="java.util.*, cn.zzsxt.lee.web.entity.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>My JSP ‘update.jsp‘ starting page</title> </head> <body> <% Student stu = (Student) request.getAttribute("stu"); %> <form action="deal_update.jsp" method="post"> 学生编号: <input type="text" value="<%=stu.getId()%>" name="id" readonly="readonly" /> <br /> 学生姓名: <input type="text" value="<%=stu.getStuName()%>" name="username" /> <br /> 学生密码: <input type="text" value="<%=stu.getStuPassword()%>" name="pwd" /> <br /> <input type="submit" value="修改" /> </form> </body> </html>
修改界面,修改数据库中的数据,预跳转至主页处理界面(查询修改后的数据,即所有数据)
<%@ page language="java" import="java.util.*, java.sql.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>My JSP ‘deal_update.jsp‘ starting page</title> </head> <body> <% String id = request.getParameter("id"); String username = request.getParameter("username"); String pwd = request.getParameter("pwd"); //1.加载驱动 Class.forName("oracle.jdbc.driver.OracleDriver"); //2.获取连接 Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl", "scott", "scott"); //3.获取预编译的statement String sql = "update students set stu_name=?, stu_pwd=? where id=?"; PreparedStatement ps = conn.prepareStatement(sql); ps.setString(1, username); ps.setString(2, pwd); ps.setString(3, id); int result = ps.executeUpdate(); if (result > 0) { response.sendRedirect("deal_index.jsp"); return; //request.getRequestDispatcher("deal_index.jsp").forward(request, response);//forward标识了跳转页面的规则,携带着request和response一起跳转页面,所以请求转发才可以传递参数 //System.out.println("我是转发之后的代码,我被执行了"); // 如果使用两个response或者request的情况下,就会报错Cannot call sendRedirect() after the response has been committed // 但是重定向直接报500,中断程序,请求转发不会中断程序,可以继续运行 //response.sendRedirect("404.jsp"); } else { //跳转错误页面 response.sendRedirect("404.jsp"); return; } %> </body> </html>
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