jsp笔记

jsp

jsp声明
jsp注解
jsp表达式
jsp脚本

<%@ page import="java.sql.DriverManager" %>
<%@ page import="java.sql.Connection" %>
<%@ page import="java.sql.Statement" %>
<%@ page import="java.sql.ResultSet" %><%--
  Created by IntelliJ IDEA.
  User: Administrator
  Date: 2019/2/23
  Time: 上午 8:25
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
    <%--jsp的声明--%>
    <%! public int count;

        public String info() {
            return "hello java";
        }
    %>
</head>
<body>
欢迎学习java web,现在的时间是：<%out.println(new java.util.Date());%>
<br>
<% for (int i = 0; i < 5; i++) {
    out.println("<font size='" + i + "'>java</font><br>");
}%>
<br>
<h4>jsp的声明</h4>
<%
    //每次刷新都会增加
    out.println(count++);
%>
<br>
<%
    //输出info()方法的返回值
    out.println(info());
%>
<h4>输出jsp表达式,注意表达式的后面不能有分号</h4>
<%=count++%>
<%=info()%>

<h4>java脚本</h4>
<table border="1" width="300px">
    <%
        for (int i = 0; i < 5; i++) {
    %>
    <tr>
        <td>循环值：</td>
        <td><%=i%>
        </td>
    </tr>
    <%
        }
    %>
</table>
<h4>脚本中使用jdbc</h4>
<%
Class.forName("com.mysql.jdbc.Driver");
    Connection conn = DriverManager.getConnection("jdbc:mysql://192.168.225.128:33306/new_info","root","123456");
    Statement sm = conn.createStatement();
    ResultSet rs = sm.executeQuery("select * from t_info");
%>
<table border="1" width="300px">
    <tr>
        <td>id</td>
        <td>info</td>
    </tr>
    <%
        while (rs.next()){
    %>
    <tr>
        <td><%=rs.getString(1)%></td>
        <td><%=rs.getString(2)%></td>
    </tr>
    <%
        }
    %>
</table>
</body>
</html>

jsp的3个编译指令

page 只针对当前页面的指令
include 用于指定包含另一个页面
taglib 用于定义和访问自定义标签
<%@ 编译指令名属性名="属性值"%>

include

<%--静态文件的导入--%>
<%@include file="error.jsp"%>
<%--动态文件建议使用的方式--%>
<jsp:include page="a.jsp"/>

jsp的7个动作指令：

jsp:forward 页面转向，将请求的处理转发到下一个页面
jsp:param 传递参数
jsp.include 动态引入一个jsp
jsp.plugin 用于下载一个javabean或applet到客户端执行
jsp.useBean 创建一个javabean的实例
jsp.setProperty 设置javabean实例的属性值
jsp.getProperty 输出。。。。

jsp:forward与jsp:param

<jsp:forward page="res.jsp">
<%--传递参数--%>
<jsp:param name="age" value="29"/>
</jsp:forward>

jsp.include

<jsp:include page="res.jsp">
<%--传递参数--%>
<jsp:param name="age" value="29"/>
</jsp:include>

<%--使用request内置对象获取age参数的值--%>
<%=request.getParameter("user")%>

其他

<jsp:useBean id="p1" class="fly.pojo.Person" scope="page"/>
<jsp:setProperty name="p1" property="name" value="zhangsan"/>
<jsp:setProperty name="p1" property="age" value="20"/>
<jsp:getProperty name="p1" property="name"/>
<jsp:getProperty name="p1" property="age"/>

<%
Person p = new Person();
pageContext.setAttribute("p2",p);
p.setName("lisi");
p.setAge(22);
%>
<%=p.getName()%>
<%=p.getAge()%>
<%=pageContext.getAttribute("p2")%>

jsp脚本中的9个内置对象

只能在jsp脚本，jsp输出表达式中使用

application 对整个web有效
config
exception
out
page 当前页面有效
pageContext
request 本次请求有效
response
session 一次会话有效

application

<body>
<%! int i;%>
<%
application.setAttribute("count",String.valueOf(++i));
%>
<%=application.getAttribute("count")%>
</body>

java代码获取


public class GetApplication extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html;charset=utf-8");
        PrintWriter writer = resp.getWriter();
        writer.println("<html><head><title>");
        writer.println("</title></head><body>");
        ServletContext sc = getServletConfig().getServletContext();
        writer.println("application中当前的count值为:");
        writer.println(sc.getAttribute("count"));
        writer.println("</body></html>");
    }
}

web.xml部分设置:

    <servlet>
        <servlet-name>get-app</servlet-name>
        <servlet-class>fly.servlet.GetApplication</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>get-app</servlet-name>
        <url-pattern>/get-app</url-pattern>
    </servlet-mapping>

pom文件：


		<dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>

读取web.xml 配置参数：

web.xml:

    <context-param>
        <param-name>driver</param-name>
        <param-value>com.mysql.jdbc.Driver</param-value>
    </context-param>

jsp页面:

<%--从配置中获取参数--%>
<%
String driver = application.getInitParameter("driver");
out.println(driver);
%>

config对象：

web.xml:

    <servlet>
        <servlet-name>servletName</servlet-name>
        <jsp-file>/e.jsp</jsp-file>
    </servlet>
    <servlet-mapping>
        <servlet-name>servletName</servlet-name>
        <url-pattern>/e.jsp</url-pattern>
    </servlet-mapping>

e.jsp:

<%--获取servlet的名字，默认为jsp--%>
<%=config.getServletName()%>

exception:

<%=exception.getClass()%>
<%=exception.getMessage()%>

pom文件关于tomcat的配置说明

	<build>
        <plugins>
            <plugin>
                <!--启动命令-->
                <!--clean tomcat7:run-->
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <version>2.2</version>
                <configuration>
                    <!--<port>9001</port>-->
                    <path>/</path>
                </configuration>
            </plugin>
        </plugins>
    </build>

jdk 1.7设置：

	<profiles>
        <profile>
            <id>jdk1.7</id>
            <activation>
                <activeByDefault>true</activeByDefault>
                <jdk>1.7</jdk>
            </activation>
            <properties>
                <maven.compiler.source>1.7</maven.compiler.source>
                <maven.compiler.target>1.7</maven.compiler.target>
                <maven.compiler.compilerVersion>1.7</maven.compiler.compilerVersion>
            </properties>
        </profile>
    </profiles>

filter过滤，访问log案例：


import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

/**
 * 过滤器，过滤所有
 */
@WebFilter(filterName = "log", urlPatterns = {"/*"})
public class MyFilter implements Filter {
    private FilterConfig config;

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        this.config = filterConfig;
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        System.out.println("开始过滤...");
        long begin = System.currentTimeMillis();
        HttpServletRequest request1 = (HttpServletRequest) request;
        System.out.println("用户请求：" + request1.getServletPath());
        chain.doFilter(request, response);
        long end = System.currentTimeMillis();
        System.out.println("过滤结束...");
        System.out.println("前往：" + request1.getRequestURI());
        System.out.println("消耗时间:" + (end - begin));


    }

    @Override
    public void destroy() {
        this.config = null;
    }
}