JSP技术

1.jsp脚本和注释

jsp脚本：

1）<%java代码%>——>内部的 java 代码翻译到 service 方法内部。

2）<%=java变量或表达式>——>会被翻译成 service 方法内部 out.print()。

3) <%! java代码%>——>会被翻译成 servlet 的成员内容。

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

      <%

      int i = 0;

      System.out.print(i);

      %>

      <%= i %>

      <%!String str = "hello world!!!"; %>

      <%= str %>

</body>

</html>

效果：

jsp注释：

1）html注释：（可见范围都有 jsp源码翻译后的 servlet 页面三者）

2）java注释： //单行注释 /*多行注释*/（jsp 源码翻译后的 servlet）

3) jsp注释：<%--注释内容--%>(jsp源码)

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2.jsp运行原理(本质就是 servlet)

jsp 在第一次被访问时会被 Web 容器翻译成 servlet ，在执行过程：

第一次访问——>HelloServlet.java——>HelloServlet_jsp.java

3.jsp 指令（3个）

jsp 的指令是指导 jsp 翻译和运作的命令，jsp 指令包括三大指令：

1）paga 指令

属性最多的一个指令，根据不同的属性，指导整个页面的特性

格式：<%@ paga 属性名1 = “属性值1”属性名2 = “属性名2”...%>

常用属性如下：

language : jsp 中嵌入的语言。

pagaEncoding ：当前 jsp 本身的编码——>内部可以包含 contentType

contentType ：文本类型。response.setContextType(text/html;charset = UTF-8);

import : 导包

errorPaga ：配置错误页面

2) include 指令

页面包含指令，可以将一个 jsp 页面包含到另一个 jsp 页面中。

格式： <%@ include file = "被包含文件地址">

3）taglib 指令

引入标签库。

index.jsp

<%@page import="java.util.List"%>

<%@page import="java.util.ArrayList"%>

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8" session = "true" errorPage = "/error.jsp"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

      <%@ include file = "/demo.jsp" %>

      <%

      int i = 0;

      System.out.print(i);

      List list = new ArrayList();

      //int y = 1/0;

      

      %>

      

      <%= i %>

      <%!String str = "hello world!!!"; %>

      <%= str %>

</body>

</html>

翻译后的 java 代码

/*

* Generated by the Jasper component of Apache Tomcat

* Version: Apache Tomcat/7.0.88

* Generated at: 2018-08-02 09:34:07 UTC

* Note: The last modified time of this file was set to

*       the last modified time of the source file after

*       generation to assist with modification tracking.

*/

package org.apache.jsp;



import javax.servlet.*;

import javax.servlet.http.*;

import javax.servlet.jsp.*;

import java.util.List;

import java.util.ArrayList;



public final class index_jsp extends org.apache.jasper.runtime.HttpJspBase

    implements org.apache.jasper.runtime.JspSourceDependent {



String str = "hello world!!!";

  private static final javax.servlet.jsp.JspFactory _jspxFactory =

          javax.servlet.jsp.JspFactory.getDefaultFactory();



  private static java.util.Map<java.lang.String,java.lang.Long> _jspx_dependants;



  static {

    _jspx_dependants = new java.util.HashMap<java.lang.String,java.lang.Long>(1);

    _jspx_dependants.put("/demo.jsp", Long.valueOf(1533132452526L));

  }



  private volatile javax.el.ExpressionFactory _el_expressionfactory;

  private volatile org.apache.tomcat.InstanceManager _jsp_instancemanager;



  public java.util.Map<java.lang.String,java.lang.Long> getDependants() {

    return _jspx_dependants;

  }



  public javax.el.ExpressionFactory _jsp_getExpressionFactory() {

    if (_el_expressionfactory == null) {

      synchronized (this) {

        if (_el_expressionfactory == null) {

          _el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();

        }

      }

    }

    return _el_expressionfactory;

  }



  public org.apache.tomcat.InstanceManager _jsp_getInstanceManager() {

    if (_jsp_instancemanager == null) {

      synchronized (this) {

        if (_jsp_instancemanager == null) {

          _jsp_instancemanager = org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(getServletConfig());

        }

      }

    }

    return _jsp_instancemanager;

  }



  public void _jspInit() {

  }



  public void _jspDestroy() {

  }



  public void _jspService(final javax.servlet.http.HttpServletRequest request, final javax.servlet.http.HttpServletResponse response)

        throws java.io.IOException, javax.servlet.ServletException {



    final javax.servlet.jsp.PageContext pageContext;

    javax.servlet.http.HttpSession session = null;

    final javax.servlet.ServletContext application;

    final javax.servlet.ServletConfig config;

    javax.servlet.jsp.JspWriter out = null;

    final java.lang.Object page = this;

    javax.servlet.jsp.JspWriter _jspx_out = null;

    javax.servlet.jsp.PageContext _jspx_page_context = null;





    try {

      response.setContentType("text/html; charset=UTF-8");

      pageContext = _jspxFactory.getPageContext(this, request, response,

                  "/error.jsp", true, 8192, true);

      _jspx_page_context = pageContext;

      application = pageContext.getServletContext();

      config = pageContext.getServletConfig();

      session = pageContext.getSession();

      out = pageContext.getOut();

      _jspx_out = out;



      out.write("\r\n");

      out.write("\r\n");

      out.write("\r\n");

      out.write("<!DOCTYPE html PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\" \"http://www.w3.org/TR/html4/loose.dtd\">\r\n");

      out.write("<html>\r\n");

      out.write("<head>\r\n");

      out.write("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=UTF-8\">\r\n");

      out.write("<title>Insert title here</title>\r\n");

      out.write("</head>\r\n");

      out.write("<body>\r\n");

      out.write("\t");

      out.write("\r\n");

      out.write("<!DOCTYPE html PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\" \"http://www.w3.org/TR/html4/loose.dtd\">\r\n");

      out.write("<html>\r\n");

      out.write("<head>\r\n");

      out.write("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=UTF-8\">\r\n");

      out.write("<title>Insert title here</title>\r\n");

      out.write("</head>\r\n");

      out.write("<body>\r\n");

      out.write("\t<br/>\r\n");

      out.write("\t<h1>This is demo jsp !!!</h1>\r\n");

      out.write("</body>\r\n");

      out.write("</html>");

      out.write('\r');

      out.write('\n');

      out.write('    ');

    int i = 0;

    System.out.print(i);

    List list = new ArrayList();

    //int y = 1/0;

    

    

      out.write("\r\n");

      out.write("\t\r\n");

      out.write("\t");

      out.print( i );

      out.write('\r');

      out.write('\n');

      out.write('    ');

      out.write('\r');

      out.write('\n');

      out.write('    ');

      out.print( str );

      out.write("\r\n");

      out.write("</body>\r\n");

      out.write("</html>");

    } catch (java.lang.Throwable t) {

      if (!(t instanceof javax.servlet.jsp.SkipPageException)){

        out = _jspx_out;

        if (out != null && out.getBufferSize() != 0)

          try {

            if (response.isCommitted()) {

              out.flush();

            } else {

              out.clearBuffer();

            }

          } catch (java.io.IOException e) {}

        if (_jspx_page_context != null) _jspx_page_context.handlePageException(t);

        else throw new ServletException(t);

      }

    } finally {

      _jspxFactory.releasePageContext(_jspx_page_context);

    }

  }

}

4.jsp 内置/隐式对象（九个）

名称	类型	描述
out	javax.servlet.jsp.JspWriter	用于页面输出
request	javax.servlet.http.HttpServletRequest	得到用户请求信息
response	javax.sevlet.http.HttpServletResponse	服务器向客户端的回应信息
config	javax.servlet.ServletConfig	服务器配置，可以获取初始化参数
session	javax.servlet.http.HttpSession	用来保存用户的信息
application	javax.servlet.ServletContext	所有用户的共享信息
pageConntext	javax.servlet.jsp.PageContext	JSP 的页面容器
exception	java.lang.Throwable	表示 JSP 页面所发生的异常，在错误页面才起作用
page	java.lang.Object	表示 JSP 页面转换后的 servlet 类的实例

（1）out 对象

out 的类型： JspWriter

out 缓冲区默认 8kb 可以设置为 0 写入 response 缓冲区

out.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

      <%

      out.write("bbbbbbbbbbbbbbbbbbbbbbbbbbbbb");

      response.getWriter().write("cccccccccccccccccccccccc");

      

      %>

      <%="dddddddddddddddddddddd" %>

</body>

</html>

输出结果：

（2）pageContext 对象

jsp页面上下文对象

作用范围：当前页面

可以获得其他 8 个内置对象！！！

pageContext.getRequest();

pageContext.getResponse();

pageContext.getOut();

pageContext.getSession();

pageContext.getPage();

pageContext.getException();

pageContext.getServletConfig();

pageContext.getServletContext();

pageContext 是一个域对象

pageContext.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; UTF-8">

<title>Insert title here</title>

</head>

<body>

      <%

      //使用 pageContext 向其他域存信息

      pageContext.setAttribute("name", "zhangsan",PageContext.REQUEST_SCOPE);

      pageContext.setAttribute("name", "lisi",PageContext.SESSION_SCOPE);

      pageContext.setAttribute("name", "wangwu",PageContext.APPLICATION_SCOPE);  

      %>

      <%=pageContext.getAttribute("name",PageContext.REQUEST_SCOPE)%>

      <%=pageContext.getAttribute("name",PageContext.SESSION_SCOPE)%>

      <%=pageContext.getAttribute("name",PageContext.APPLICATION_SCOPE)%>

      

      <!--  pageContext.findAttribute会从小到大搜索范围内的 name -->

      <%= pageContext.findAttribute("name") %>

      <%

      pageContext.getRequest();

      pageContext.getResponse();

      pageContext.getOut();

      pageContext.getSession();

      pageContext.getPage();

      pageContext.getException();

      pageContext.getServletConfig();

      pageContext.getServletContext();

      %>

</body>

</html>

四大作用域的总结：

page 域（pageContext）：当前 jsp 页面。

request 域：一次请求。

session 域：一次会话。

application 域：整个 web 应用。

1.jsp 标签

1）页面包含（动态包含）：<jsp : include page = "被包含的页面"/>

include1.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

      <!--包含 include2  -->

      <h1>This is include1 !!!</h1>

      <jsp:include page="include2.jsp"></jsp:include>

</body>

</html>

include2.jsp效果：

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

      <h1>This is include2 !!!</h1>

</body>

</html>

2）请求转发（请求转发）：<jsp : forward page = "要转发的资源"/>

forward1.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

      

      <h1>This is forward1 !!!</h1>

      

</body>

</html>

forward2.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

      <h1>This is forward2 !!!</h1>

</body>

</html>

效果：

静态包含和动态包含的区别？

demo : 商品页面的展示

数据库的部分：

CREATE TABLE `product` (

  `pid` VARCHAR(32) NOT NULL,

  `pname` VARCHAR(50) DEFAULT NULL,

  `market_price` DOUBLE DEFAULT NULL,

  `shop_price` DOUBLE DEFAULT NULL,

  `pimage` VARCHAR(200) DEFAULT NULL,

  `pdate` DATE DEFAULT NULL,

  `is_hot` INT(11) DEFAULT NULL,

  `pdesc` VARCHAR(255) DEFAULT NULL,

  `pflag` INT(11) DEFAULT NULL,

  `cid` VARCHAR(32) DEFAULT NULL,

  PRIMARY KEY (`pid`)

)

表结构：

项目结构：

实体类：

package com.ma.domain;

public class Product {

      private String pid;

      private String pname;

      private double market_price;

      private double shop_price;

      private String pimage;

      private String pdate;

      private int is_hot;

      private String pdesc;

      private int pflag;

      private String cid;

      public String getPid() {

            return pid;

      }

      public void setPid(String pid) {

            this.pid = pid;

      }

      public String getPname() {

            return pname;

      }

      public void setPname(String pname) {

            this.pname = pname;

      }

      public double getMarket_price() {

            return market_price;

      }

      public void setMarket_price(double market_price) {

            this.market_price = market_price;

      }

      public double getShop_price() {

            return shop_price;

      }

      public void setShop_price(double shop_price) {

            this.shop_price = shop_price;

      }

      public String getPimage() {

            return pimage;

      }

      public void setPimage(String pimage) {

            this.pimage = pimage;

      }

      public String getPdate() {

            return pdate;

      }

      public void setPdate(String pdate) {

            this.pdate = pdate;

      }

      public int getIs_hot() {

            return is_hot;

      }

      public void setIs_hot(int is_hot) {

            this.is_hot = is_hot;

      }

      public String getPdesc() {

            return pdesc;

      }

      public void setPdesc(String pdesc) {

            this.pdesc = pdesc;

      }

      public int getPflag() {

            return pflag;

      }

      public void setPflag(int pflag) {

            this.pflag = pflag;

      }

      public String getCid() {

            return cid;

      }

      public void setCid(String cid) {

            this.cid = cid;

      }

      @Override

      public String toString() {

            return "Product [pid=" + pid + ", pname=" + pname + ", market_price="

                        + market_price + ", shop_price=" + shop_price + ", pimage="

                        + pimage + ", pdate=" + pdate + ", is_hot=" + is_hot

                        + ", pdesc=" + pdesc + ", pflag=" + pflag + ", cid=" + cid

                        + "]";

      }

      

      

}

ProductListServlet

package com.ma.servlet;

import java.io.IOException;

import java.sql.SQLException;

import java.util.List;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

importorg.apache.commons.dbutils.QueryRunner;

importorg.apache.commons.dbutils.handlers.BeanListHandler;

import com.ma.domain.Product;

import com.ma.utils.C3P0Utils;

/**

 * Servlet implementation class ProductListServlet

 */

public class ProductListServlet extends HttpServlet {

      protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

            //准备好所有数据-----List<Product>

            QueryRunner runner = new QueryRunner(C3P0Utils.getDataSouce());

            String sql = "select * from product";

            List<Product> productList = null;

            try {

                  

                  productList = runner.query(sql, new BeanListHandler<Product>(Product.class));

            

            } catch (SQLException e) {

                  e.printStackTrace();

            }

            //商品集合准备好

            //将数据存到 request 域转发给 product_list.jsp 显示

            request.setAttribute("productList", productList);

            request.getRequestDispatcher("/product_list.jsp").forward(request, response);;

            

      }

      /**

       * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)

       */

      protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

            // TODO Auto-generated method stub

      }

}

工具类：

package com.ma.utils;

import java.sql.Connection;

import java.sql.SQLException;

import javax.management.RuntimeErrorException;

import javax.sql.DataSource;

importcom.mchange.v2.c3p0.ComboPooledDataSource;

public class C3P0Utils {

      private static ComboPooledDataSource dataSource = new ComboPooledDataSource();

      public static DataSource getDataSouce(){

            return dataSource;

      }

      

      public static Connection getConnection(){

            try {

                  return dataSource.getConnection();

            } catch (SQLException e) {

                  

                  throw new RuntimeException(e);

            }

      }

}

配置文件：

<?xml version="1.0" encoding="UTF-8"?>

<c3p0-config>

  <default-config>

    <property name="driverClass">com.mysql.jdbc.Driver</property>

      <property name="jdbcUrl">jdbc:mysql:///web17?useUnicode=true&amp;characterEncoding=UTF-8</property>

      <property name="user">root</property>

      <property name="password">123456</property>

      <property name="initialPoolSize">5</property>

      <property name="maxPoolSize">20</property>

  </default-config>



  <named-config name="oracle">

    <property name="driverClass">com.mysql.jdbc.Driver</property>

      <property name="jdbcUrl">jdbc:mysql:///web_07</property>

      <property name="user">root</property>

      <property name="password">123</property>

  </named-config>



</c3p0-config>

效果：

JavaWeb 动态页面技术之 jsp