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2019.03.10
jsp
page指令
使用此属性，可以定义一个jsp页面的相关属性
<%@ page contentType="text/html;charset=UTF-8" language="java" %> 设置该页面的类型为text/html类型，其中编码为Unicode 类型的UTF-8 语言为java
从Tomcat安装目录中可以找到可以使用的MIME类型
<mime-mapping> <extension>ait</extension> <mime-type>application/vnd.dvb.ait</mime-type></mime-mapping> 错误页设置
设置page指令的errorPage属性，设置错误页
<%-- Created by IntelliJ IDEA. User: ming Date: 19-3-6 Time: 下午9:29 To change this template use File | Settings | File Templates.--%><%@ page contentType="application/vnd.dvb.ait;charset=UTF-8" language="java" %><%@ page errorPage="error.jsp" %><html> <head> <title>$Title$</title> </head> <body> <% // 运行错误 int result = 10 / 0; %>
</body></html> 设置如果出现错误，跳转到error.jsp文件
> 错误页的跳转属于服务器端跳转
数据库连接操作
访问网址
https://search.maven.org/artifact/mysql/mysql-connector-java/8.0.15/jar
输入依赖
<dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.15</version></dependency> maven安装驱动
访问网址
https://search.maven.org/artifact/mysql/mysql-connector-java/8.0.15/jar
输入依赖
<dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.15</version></dependency> jsp书写代码，并网页展示
<%@ page import="java.sql.*" %><html><body><h2>Hello World!</h2><%! // 数据库驱动程序 public static final String DBDRIVER = "com.mysql.cj.jdbc.Driver"; // 数据库连接地址 public static final String DBURL = "jdbc:mysql://47.94.95.84:32786/test"; // 用户名 public static final String DBUSER = "root"; // 密码 public static final String DBPASS = "ABCcba20170607";%><% // 声明数据库连接对象 Connection connection = null; // 连接 PreparedStatement preparedStatement = null; // 结果集 ResultSet resultSet = null; String sql = "SELECT * from emp";%><% try{ Class.forName(DBDRIVER); // 数据库连接 connection = DriverManager.getConnection(DBURL, DBUSER, DBPASS); // 实例化sql preparedStatement = connection.prepareStatement(sql); // 查询 resultSet = preparedStatement.executeQuery(); while(resultSet.next()){ int empon = resultSet.getInt(1); String ename = resultSet.getString(2); String job = resultSet.getString(3); %> <%=empon%> <%=ename%> <%=job%> <% } }catch (Exception e){ System.out.println(e); }finally { resultSet.close(); preparedStatement.close(); connection.close(); }%></body></html>
包含指令
网页分为头尾中
静态包含
在jsp编译的时候插入一个包含文本或代码的文件。包含过程为静态的,代码文件包含，生成一个完整的jsp文件，再次包含生成class文件，加载进入容器。
<html><body> <%@include file="info.html"%> <%@include file="info.inc"%></body></html> 动态包含
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<%-- Created by IntelliJ IDEA. User: ming Date: 19-3-9 Time: 下午3:43 To change this template use File | Settings | File Templates.--%><%@ page contentType="text/html;charset=UTF-8" language="java" %>参数1<%=request.getParameter("name")%>参数2<%=request.getParameter("info")%> <%-- Created by IntelliJ IDEA. User: ming Date: 19-3-9 Time: 下午4:51 To change this template use File | Settings | File Templates.--%><%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head> <title>Title</title></head><body> <% String username = "LiHua"; %> <h1>动态传递参数</h1> <jsp:include page="./receive_param.jsp"> <jsp:param name="name" value="<%=username%>"/> <jsp:param name="info" value="ming"/> </jsp:include></body></html>
运行以后可以发现显示出结果
> 两种包含，静态包含是先包含，后处理，动态包含为先处理后包含
跳转指令
此跳转为服务端跳转
即一个request传递到另外一个page
<%-- Created by IntelliJ IDEA. User: ming Date: 19-3-9 Time: 下午5:14 To change this template use File | Settings | File Templates.--%><%@ page contentType="text/html;charset=UTF-8" language="java" %><h1>这是跳转后的页面</h1><h2><%=request.getParameter("name")%></h2><h2><%=request.getParameter("info")%></h2>
<%--
Created by IntelliJ IDEA. User: ming Date: 19-3-9 Time: 下午5:11 To change this template use File | Settings | File Templates.--%><%@ page contentType="text/html;charset=UTF-8" language="java" %><% String username = "LiHua";%><jsp:forward page="forward_demo02.jsp"> <jsp:param name="name" value="<%=username%>"/> <jsp:param name="info" value="ming"/></jsp:forward> jsp 实栗 jsp + jdbc 实现登录
实现思路
一个表单页，输入用户登录和密码，然后信息提交到jsp页面进行验证，如果可以服务器跳转到登录成功页，失败，跳转到错误页
> 跳转的时候窗口的URL地址会发生变化
代码如下
编写登录代码
登录
<!DOCTYPE html><html lang="zh_CN"><head> <meta charset="UTF-8"> <title>登录</title></head><body> <h1>登录操作</h1> <form action="login_check.jsp" method="post"> <h1>用户登录</h1> <p> 登录id <input type="text" name="id"/> </p> <p> 登录密码 <input type="password" name="password"/> </p> <input type="submit" value="登录"/> <input type="reset" value="重置"/> </form></body></html>
登录处理
<%@ page import="java.sql.*" %><%-- Created by IntelliJ IDEA. User: ming Date: 19-3-9 Time: 下午5:50 To change this template use File | Settings | File Templates.--%><%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head> <title>Title</title></head><body><%! // 数据库驱动程序 public static final String DBDRIVER = "com.mysql.cj.jdbc.Driver"; // 数据库连接地址 public static final String DBURL = "jdbc:mysql://47.94.95.84:32786/test"; // 用户名 public static final String DBUSER = "root"; // 密码 public static final String DBPASS = "ABCcba20170607";%><% // 连接对象 Connection connection = null; // 操作 PreparedStatement preparedStatement = null; // 结果 ResultSet resultSet = null; // 标志位 boolean falge = false; // 用户真实姓名 String name = null;%><% try{ Class.forName(DBDRIVER); // 获得连接 connection = DriverManager.getConnection(DBURL, DBUSER, DBPASS); // 编写sql验证ID 密码 String sql = "SELECT name FROM user WHERE userid = ? AND password = ?"; // 实例化操作对象 preparedStatement = connection.prepareStatement(sql); // 设置查询内容 preparedStatement.setString(1, request.getParameter("id")); preparedStatement.setString(2, request.getParameter("password")); // 执行查询 resultSet = preparedStatement.executeQuery(); // 如果可以查询到，表示合法用户 if(resultSet.next()){ name = resultSet.getString(1); // 修改标志位 falge = true; } }catch (Exception e){ e.printStackTrace(); }finally { try{ resultSet.close(); preparedStatement.close(); connection.close(); }catch (Exception e){ e.printStackTrace(); } }%><% // 登录成功 if(falge){ // 进行服务器端跳转%> <jsp:forward page="./login_sucess.jsp"> <jsp:param name="uname" value="<%=name%>"/> </jsp:forward><% }else{%> <jsp:forward page="./login_failure.html"/><% }%></body></html> 登录完成
<%-- Created by IntelliJ IDEA. User: ming Date: 19-3-9 Time: 下午10:22 To change this template use File | Settings | File Templates.--%><%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head> <title>Title</title></head><body><h1>登录成功</h1><%=request.getParameter("uname")%></body></html> 登录失败
<%-- Created by IntelliJ IDEA. User: ming Date: 19-3-9 Time: 下午10:22 To change this template use File | Settings | File Templates.--%><%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head> <title>Title</title></head><body><h1>登录成功</h1><%=request.getParameter("uname")%></body></html> 效果演示