day14学习总结

一、JSP九大内置对象

九大内置对象的创建：

        是由Tomcat容器创建的

二、JSP内置对象中的四大作用域对象

 方法：

        

使用el表达式来获取作用域对象值：

        语法：

                ${xxxScope.键}  xxx 表示内置对象的名称

        作用域大小从小到大排序：

                pageContext < request 

        注意点：

            如果内置对象的作用域下的键名都相同的情况下，el表达式优先获取的是作用域范围小的值 

测试：

<%--
  Created by IntelliJ IDEA.
  User: 86182
  Date: 2022/9/5
  Time: 10:01
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
  
    
  
  
  <%
    pageContext.setAttribute("pname","班长");
    request.setAttribute("rname","梁男");
    session.setAttribute("sname","黑福");
    application.setAttribute("aname","肥男");
 
    request.setAttribute("upwd",11);
    session.setAttribute("upwd",22);
    application.setAttribute("upwd",33);
    //转发
    request.getRequestDispatcher("info.jsp").forward(request,response);
    //重定向
    //response.sendRedirect("info.jsp");
  %>
  
 
 
 
 
<%--
  Created by IntelliJ IDEA.
  User: 86182
  Date: 2022/9/5
  Time: 10:02
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
    
${pageScope.pname}
${requestScope.rname}
${sessionScope.sname}
${applicationScope.aname}
${upwd}//获取的是11

三、JSP动态标签库

简介：

        JSP动态标签库，主要用于简化页面java代码的编写，所有的jsp页面都可以使用

转发：  

"info.jsp">

动态引入公共页面：

"kk.jsp">

动态引入与静态引入的区别：

        动态引入：

                先翻译并编译两个jsp文件，再进行合并   效率低

        静态引入：

                先合并两个jsp文件，在翻译并编译合并后的jsp文件  效率高

访问路径的设置：

        在实际项目一般使用的绝对路径 在jsp中设置绝对路径跳转到Servlet

        解决访问路径错误的问题 ：在访问路径前加入${pageContext.request.contextPath}

四、分页

需求：

        

 

基础搭建：

        创建项目：

 

        数据库：

 

功能实现：

        Student实体类：

        

package com.qf.entity;
 
import java.io.Serializable;
 
public class Student implements Serializable {
    private int sid;
    private  String sname;
    private  String sex;
    private String hobby;
 
    public Student() {
    }
 
    public Student(int sid, String sname, String sex, String hobby) {
        this.sid = sid;
        this.sname = sname;
        this.sex = sex;
        this.hobby = hobby;
    }
 
    public int getSid() {
        return sid;
    }
 
    public void setSid(int sid) {
        this.sid = sid;
    }
 
    public String getSname() {
        return sname;
    }
 
    public void setSname(String sname) {
        this.sname = sname;
    }
 
    public String getSex() {
        return sex;
    }
 
    public void setSex(String sex) {
        this.sex = sex;
    }
 
    public String getHobby() {
        return hobby;
    }
 
    public void setHobby(String hobby) {
        this.hobby = hobby;
    }
 
    @Override
    public String toString() {
        return "Student{" +
                "sid=" + sid +
                ", sname='" + sname + '\'' +
                ", sex='" + sex + '\'' +
                ", hobby='" + hobby + '\'' +
                '}';
    }
}

        pageUtils类：

package com.qf.utils;
 
import java.util.List;
 
public class PageUtils  {
    //当前页
    private Integer currentPageNo;
    //页量
    private Integer pageSize;
    //总记录数
    private Integer totalPageCount;
    //总页数
    private Integer totalPageSize;
    //集合
    private List commenList;
 
    public Integer getCurrentPageNo() {
        return currentPageNo;
    }
 
    public void setCurrentPageNo(Integer currentPageNo) {
        this.currentPageNo = currentPageNo;
    }
 
    public Integer getPageSize() {
        return pageSize;
    }
 
    public void setPageSize(Integer pageSize) {
        this.pageSize = pageSize;
    }
 
    public Integer getTotalPageCount() {
        return totalPageCount;
    }
 
    public void setTotalPageCount(Integer totalPageCount) {
        this.totalPageCount = totalPageCount;
    }
 
    public Integer getTotalPageSize() {
        return totalPageSize;
    }
 
    public void setTotalPageSize(Integer totalPageSize) {
        this.totalPageSize = totalPageSize;
    }
 
    public List getCommenList() {
        return commenList;
    }
 
    public void setCommenList(List commenList) {
        this.commenList = commenList;
    }
 
    @Override
    public String toString() {
        return "PageUtils{" +
                "currentPageNo=" + currentPageNo +
                ", pageSize=" + pageSize +
                ", totalPageCount=" + totalPageCount +
                ", totalPageSize=" + totalPageSize +
                ", commenList=" + commenList +
                '}';
    }
}

        DBUtils类：

package com.qf.utils;
 
import com.alibaba.druid.pool.DruidDataSourceFactory;
import org.apache.commons.dbutils.QueryRunner;
 
import javax.sql.DataSource;
import java.io.InputStream;
import java.util.Properties;
 
public enum DBUtils {
    DB;
    public QueryRunner qr;
    DBUtils(){
        try {
            InputStream is = DBUtils.class.getResourceAsStream("db.properties");
            Properties pro  = new Properties();
            pro.load(is);
            DataSource ds = DruidDataSourceFactory.createDataSource(pro);
            qr = new QueryRunner(ds);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

        StudentDao接口：

package com.qf.dao;
 
import com.qf.entity.Student;
 
import java.util.List;
 
public interface StudentDao {
    //查询总记录数
    Integer selectCount(String sname);
    //查询当前页 记录集合
    List selectByPage(Integer currentPageNo,Integer pageSize,String sname);
}

        StudentDaoImpl类：

package com.qf.dao.impl;
 
import com.qf.dao.StudentDao;
import com.qf.entity.Student;
import com.qf.utils.DBUtils;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;
 
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
 
public class StudentDaoImpl implements StudentDao {
    private QueryRunner qr = DBUtils.DB.qr;
    @Override
    public Integer selectCount(String sname) {
 
        Long count=null;
        try {
            //使用StringBuffer可以动态拼接SQL语句
            StringBuffer sb = new StringBuffer("select count(1) from student where 1=1");
            //定义集合
            List