Servlet&jstl&el&过滤器&监听器&连接池--复习

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Servlet的生命周期

加 jar@WebServlet(        name="BaseControl",        urlPatterns = {"/base1"},        initParams = {                @WebInitParam(name="page1",value="/page1.jsp"),                @WebInitParam(name="page2",value="/page2.jsp")        })public class BaseControl extends HttpServlet {    private Map<String ,String> map=new HashMap<>();    public BaseControl(){//1.创建    }    @Override    public void init(ServletConfig config) throws ServletException {//初始化        map.put("page1",config.getInitParameter("page1"));        map.put("page2",config.getInitParameter("page2"));    }    @Override//3.做服务    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        super.doGet(req,resp);    }    @Override    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        System.out.println("servlet success!");//        resp.setContentType("text/html");//        resp.setCharacterEncoding("UTF-8");//        PrintWriter out=resp.getWriter();//        out.print("haoba");//        out.flush();//        out.close();        String action=req.getParameter("action");        String path=map.get(action);        RequestDispatcher dispatcher=req.getRequestDispatcher(path);        dispatcher.forward(req,resp);    }    @Override//4.销毁    public void destroy() {        super.destroy();    }}

jstl&el基础应用

加jar jstl-1.2.jar

<%@ page import="java.util.Enumeration" %><%@ page import="java.util.HashMap" %><%@ page import="java.util.Vector" %><%--  Created by IntelliJ IDEA.  User: fangjiejie  Date: 2017/11/13  Time: 19:56  To change this template use File | Settings | File Templates.--%><%@ page contentType="text/html;charset=UTF-8" language="java" %><%@taglib prefix="lyf" uri="http://java.sun.com/jsp/jstl/core" %><%@taglib prefix="ff" uri="http://java.sun.com/jsp/jstl/fmt" %><html><head>    <title>Title</title></head><body><lyf:out  value="helloworld"></lyf:out><lyf:set var="xiao" value="ming"></lyf:set><br><lyf:out value="${xiao}"></lyf:out><%   session.setAttribute("li","yafang");%><lyf:out value="${sessionScope.li}"></lyf:out>${sessionScope.li}<jsp:useBean id="person" class="com.LYF.Person"></jsp:useBean><lyf:set target="${person}" property="username" value="xiaosi"></lyf:set><lyf:if test="${person.username==ee}">    她叫小四</lyf:if><lyf:remove var="xiao"></lyf:remove><lyf:out value="${xiao}"/><lyf:set value="20" target="${person}" property="age"></lyf:set><lyf:choose>    <lyf:when test="${person.age<=18}">        <span>年龄小于18</span>    </lyf:when>    <lyf:when test="${person.age>10&&person.age<50}">        <span>年龄在18岁到50岁</span>    </lyf:when>    <lyf:otherwise>        <span>已经老了</span>    </lyf:otherwise></lyf:choose><lyf:forEach var="i" begin="0" end="20" step="2">    <lyf:out value="${i}"></lyf:out></lyf:forEach><%    Vector vector=new Vector();    vector.add("我");    vector.add("已");    vector.add("经");    vector.add("把");    vector.add("你");    vector.add("忘");    vector.add("了");    Enumeration myEnum=vector.elements();    request.setAttribute("myEnum",myEnum);    HashMap hashMap=new HashMap();    hashMap.put("A","a");    hashMap.put("B","b");    hashMap.put("C","c");    hashMap.put("D","d");    request.setAttribute("myMap",hashMap);%><lyf:forEach var="h" items="${requestScope.myMap}" varStatus="status">    <lyf:out value="${status.index}">:</lyf:out><lyf:out value="${h.key}">:</lyf:out>    <lyf:out value="${h.value}"></lyf:out></lyf:forEach><br><ff:formatNumber value="784523" pattern="0,000"></ff:formatNumber><br><jsp:useBean id="now" class="java.util.Date"></jsp:useBean><ff:formatDate value="${now}" var="result" pattern="yyyy-MM-dd hh:mm:ss"></ff:formatDate>${result}<br><lyf:set var="ft" value="小*名*同*学"></lyf:set><lyf:forTokens items="${ft}" delims="*" var="name" varStatus="status">    ${status.count}.${name} <br></lyf:forTokens></body></html>

过滤器

package com.lyf.filter;import javax.servlet.*;import javax.servlet.annotation.WebFilter;import javax.servlet.annotation.WebInitParam;import java.io.IOException;/** * Created by fangjiejie on 2017/11/13. */@WebFilter(filterName = "encodingFilter",        urlPatterns = "/*",        initParams = @WebInitParam(name="encoder",value = "utf-8"))public class EncodingFilter implements Filter{    String encoding;    @Override    public void init(FilterConfig filterConfig) throws ServletException {        encoding=filterConfig.getInitParameter("encoder");    }    @Override    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {        servletRequest.setCharacterEncoding(encoding);        filterChain.doFilter(servletRequest,servletResponse);    }    @Override    public void destroy() {    }}

监听器

package com.lyf.listener; /** * Created by fangjiejie on 2017/11/13. */import javax.servlet.ServletContextEvent;import javax.servlet.annotation.WebListener;import javax.servlet.http.HttpSessionBindingEvent;import javax.servlet.http.HttpSessionEvent;import javax.servlet.http.HttpSessionListener;@WebListener()public class OnlineListener implements HttpSessionListener {    public static int count;    // Public constructor is required by servlet spec    public OnlineListener() {    }    // -------------------------------------------------------    // ServletContextListener implementation    // -------------------------------------------------------    public void contextInitialized(ServletContextEvent sce) {      /* This method is called when the servlet context is         initialized(when the Web application is deployed).          You can initialize servlet context related data here.      */    }    public void contextDestroyed(ServletContextEvent sce) {      /* This method is invoked when the Servlet Context          (the Web application) is undeployed or          Application Server shuts down.      */    }    // -------------------------------------------------------    // HttpSessionListener implementation    // -------------------------------------------------------    public void sessionCreated(HttpSessionEvent se) {     ++count;      /* Session is created. */    }    public void sessionDestroyed(HttpSessionEvent se) {     --count;      /* Session is destroyed. */    }    // -------------------------------------------------------    // HttpSessionAttributeListener implementation    // -------------------------------------------------------    public void attributeAdded(HttpSessionBindingEvent sbe) {      /* This method is called when an attribute          is added to a session.      */    }    public void attributeRemoved(HttpSessionBindingEvent sbe) {      /* This method is called when an attribute         is removed from a session.      */    }    public void attributeReplaced(HttpSessionBindingEvent sbe) {      /* This method is invoked when an attibute         is replaced in a session.      */    }}

连接池

作用：
连接池是将已经创建好的连接保存在池中，当有请求来时，直接使用已经创建好的连接对数据库进行访问。这样省略了创建连接和销毁连接的过程。这样性能上得到了提高。
三种连接池：
1.DBCP连接池
加jar
commons-dbcp.jar
commons-pool.jar
配置文档 dbcp.ini

#连接设置driverClassName=com.mysql.jdbc.Driverurl=jdbc:mysql://127.0.0.1:3306/bz?useUnicode=true&characterEncoding=UTF-8username=rootpassword=123321#<!-- 初始化连接 -->initialSize=10#最大连接数量maxActive=50#<!-- 最大空闲连接 -->maxIdle=20#<!-- 最小空闲连接 -->minIdle=5#<!-- 超时等待时间以毫秒为单位 60000毫秒/1000等于60秒 -->maxWait=60000#JDBC驱动建立连接时附带的连接属性属性的格式必须为这样：[属性名=property;]#注意："user" 与 "password" 两个属性会被明确地传递，因此这里不需要包含他们。connectionProperties=useUnicode=true;characterEncoding=utf-8#指定由连接池所创建的连接的自动提交（auto-commit）状态。defaultAutoCommit=true#driver default 指定由连接池所创建的连接的只读（read-only）状态。#如果没有设置该值，则“setReadOnly”方法将不被调用。（某些驱动并不支持只读模式，如：Informix）defaultReadOnly=#driver default 指定由连接池所创建的连接的事务级别（TransactionIsolation）。#可用值为下列之一：

代码：

package com.lyf.db;import org.apache.commons.dbcp2.BasicDataSourceFactory;import javax.sql.DataSource;import java.sql.Connection;import java.sql.SQLException;import java.util.Properties;/** * Created by fangjiejie on 2017/11/13. */public class DBCP {    private static DataSource ds=null;    private static Connection conn=null;    static{        Properties pro=new Properties();        try {            pro.load(DBCP.class.getClassLoader().getResourceAsStream("dbcp.ini"));            ds= BasicDataSourceFactory.createDataSource(pro);        } catch (Exception e) {            e.printStackTrace();        }    }    public static Connection getConnection(){        try {            conn=ds.getConnection();        } catch (SQLException e) {            e.printStackTrace();        }        return conn;    }}

2.C3P0连接池
Hibernate推荐使用它，自动清理不适用的Connection, Statement,ResultSet
加 jar
c3p0-0.9.1.2.jar
配置文档
c3p0-config.xml

<?xml version="1.0" encoding="UTF-8"?><c3p0-config>    <default-config>        <property name="automaticTestTable">con_test</property>        <property name="checkoutTimeout">30000</property>        <property name="idleConnectionTestPeriod">30</property>        <property name="initialPoolSize">10</property>        <property name="maxIdleTime">30</property>        <property name="maxPoolSize">100</property>        <property name="minPoolSize">10</property>        <property name="maxStatements">200</property>    </default-config>    <named-config name="mysql">        <property name="driverClass">com.mysql.jdbc.Driver</property>        <property name="jdbcUrl">jdbc:mysql://localhost:3306/bz?useUnicode=true&amp;characterEncoding=utf-8        </property>        <property name="user">root</property>         <property name="password">123321</property>        <property name="acquireIncrement">5</property>        <property name="initialPoolSize">10</property>        <property name="minPoolSize">5</property>        <property name="maxPoolSize">30</property>    </named-config></c3p0-config>

package com.lyf.db;import com.mchange.v2.c3p0.ComboPooledDataSource;import javax.activation.DataSource;import java.sql.Connection;import java.sql.SQLException;/** * Created by fangjiejie on 2017/11/13. */public class C3P0 {    private static DataSource ds=null;    private static Connection conn=null;    static {        ComboPooledDataSource cs=new ComboPooledDataSource("mysql") ;        try {            conn=cs.getConnection();        } catch (SQLException e) {            e.printStackTrace();        }    }    public static  Connection getConnection(){        return conn;    }}

3.Druid连接池
性能更好
加jar
druid-1.0.26.jar
配置文档
druid.ini

#mysql数据库url=jdbc:mysql://127.0.0.1:3306/bz?useUnicode=true&characterEncoding=UTF-8username=rootpassword=123321#filters=stat#最大连接数量maxActive=20#初始化连接数量initialSize=10#超时等待时间以毫秒为单位maxWait=12000#最小空闲连接minIdle=5#校验连接池中限制时间超过minEvictableIdleTimeMillis的连接对象timeBetweenEvictionRunsMillis=6000#连接在池中保持空闲而不被空闲连接回收器线程(如果有)回收的最小时间值，单位毫秒#minEvictableIdleTimeMillis=#SQL查询,用来验证从连接池取出的连接,在将连接返回给调用者之前validationQuery=SELECT now();#指明连接是否被空闲连接回收器(如果有)进行检验.#如果检测失败,则连接将被从池中去除.testWhileIdle=true#指明是否在从池中取出连接前进行检验,如果检验失败,则从池中去除连接并尝试取出另一个.testOnBorrow=false#指明是否在归还到池中前进行检验testOnReturn=false#poolPreparedStatements=true#maxPoolPreparedStatementPerConnectionSize=20

package com.lyf.db;import com.alibaba.druid.pool.DruidDataSourceFactory;import javax.sql.DataSource;import java.sql.Connection;import java.sql.SQLException;import java.util.Properties;/** * Created by fangjiejie on 2017/4/10. */public class Druid {    private static Connection conn=null;    private static DataSource ds=null;    static {        Properties pro =new Properties();        try {            pro.load(Druid.class.getClassLoader().getResourceAsStream("druid.ini"));            ds= DruidDataSourceFactory.createDataSource(pro);        } catch (Exception e) {            e.printStackTrace();        }    }    public static Connection getConnection(){        try {            conn=ds.getConnection();        } catch (SQLException e) {            e.printStackTrace();        }        return conn;    }}

项目—对记录增删改查(Servlet&jstl&el&过滤器&监听器&连接池)

github地址：
https://github.com/stubbornA/reviewServletPro

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