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>$Titlelt;/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
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
<%--
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
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