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
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
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>