JavaWeb之Filter实现页面静态化

第一次访问：Filter会自定义response输出缓存html资源

第二次访问：就直接访问静态页面html

创建表t_book

CREATE TABLE t_book(
   bid CHAR(30) PRIMARY KEY,
   bname VARCHAR(100),
   price NUMERIC(10,2),
   category INT
);

INSERT INTO t_book(bid,bname,price,category) VALUES('b1','JAVASE_1',10,1);
INSERT INTO t_book(bid,bname,price,category) VALUES('b2','JAVASE_2',15,1);
INSERT INTO t_book(bid,bname,price,category) VALUES('b3','JAVASE_3',20,1);
INSERT INTO t_book(bid,bname,price,category) VALUES('b4','JAVASE_4',25,1);
INSERT INTO t_book(bid,bname,price,category) VALUES('b5','JAVAEE_1',30,2);
INSERT INTO t_book(bid,bname,price,category) VALUES('b6','JAVAEE_2',35,2);
INSERT INTO t_book(bid,bname,price,category) VALUES('b7','JAVAEE_3',40,2);
INSERT INTO t_book(bid,bname,price,category) VALUES('b8','JAVAFRAMEWORD_1',45,3);
INSERT INTO t_book(bid,bname,price,category) VALUES('b9','JAVAFRAMEWORD_2',50,3);

SELECT * FROM t_book;

Book.java

package zh.response.demo;

public class Book {

	private String bid;
	private String bname;
	private double price;
	private int category;

	public Book() {

	}

	public Book(String bid, String bname, double price, int category) {
		super();
		this.bid = bid;
		this.bname = bname;
		this.price = price;
		this.category = category;
	}

	public String getBid() {
		return bid;
	}

	public void setBid(String bid) {
		this.bid = bid;
	}

	public String getBname() {
		return bname;
	}

	public void setBname(String bname) {
		this.bname = bname;
	}

	public double getPrice() {
		return price;
	}

	public void setPrice(double price) {
		this.price = price;
	}

	public int getCategory() {
		return category;
	}

	public void setCategory(int category) {
		this.category = category;
	}

	@Override
	public String toString() {
		return "Book [bid=" + bid + ", bname=" + bname + ", price=" + price
				+ ", category=" + category + "]";
	}

}

BookDao.java

package zh.response.demo;

import java.sql.SQLException;
import java.util.List;

import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanListHandler;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class BookDao {

	private QueryRunner queryRunner = new QueryRunner(
			new ComboPooledDataSource());

	public BookDao() {

	}
	
	// 查询所有
	public List<Book> findAll() {

		String sql = "select * from t_book";
		try {
			List<Book> BookList = queryRunner.query(sql,
					new BeanListHandler<Book>(Book.class));
			return BookList;
		} catch (SQLException cause) {
			throw new RuntimeException("查询所有图书失败", cause);
		}

	}

	// 按分类号查询
	public List<Book> findByCategory(int category) {

		String sql = "select * from t_book where category = ?";
		try {
			List<Book> bookList = queryRunner.query(sql,
					new BeanListHandler<Book>(Book.class), category);
			return bookList;
		} catch (SQLException cause) {
			throw new RuntimeException("查询所有图书失败", cause);
		}

	}

}

bookIndex.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>Book Index</title>
</head>
<body>
	<a href="${pageContext.request.contextPath}/BookServlet">全部图书</a><br>
	<a href="${pageContext.request.contextPath}/BookServlet?category=1">JAVASE图书</a><br>
	<a href="${pageContext.request.contextPath}/BookServlet?category=2">JAVAEE图书</a><br>
	<a href="${pageContext.request.contextPath}/BookServlet?category=3">JAVAFRAMEWORK图书</a><br>
</body>
</html>

BookServlet.java

package zh.response.demo;

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class BookServlet extends HttpServlet {

	private static final long serialVersionUID = 1L;

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

		BookDao bookDao = new BookDao();
		List<Book> bookList = null;
		String category = request.getParameter("category");
		if (category == null || category.trim().isEmpty()) {
			//查询所有
			bookList = bookDao.findAll();
		} else {
			// 按分类号查询
			bookList = bookDao.findByCategory(Integer.parseInt(category));
		}

		request.setAttribute("bookList", bookList);
		// 转发
		request.getRequestDispatcher("/show.jsp").forward(request, response);
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}

}

show.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8" import="java.util.*" import="zh.response.demo.Book"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!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>Book Show</title>
</head>
<body>
	<table border="1" cellpadding="1">
		<tr>
		 <td>图书名称</td>
		 <td>图书单价</td>
		 <td>图书分类</td>
		</tr>
		<c:forEach var="book" items="${requestScope.bookList}">
			<tr>
				<td>${book.bname}</td>
				<td>${book.price}</td>
				<td>${book.category}</td>
			</tr>
		</c:forEach>
	</table>
</body>
</html>

BookFilter.java

package zh.response.demo;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class BookFilter implements Filter {

	private FilterConfig config;

	public void init(FilterConfig fConfig) throws ServletException {
		this.config = fConfig;
	}

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		
		// 强转
		HttpServletRequest req = (HttpServletRequest) request;
		HttpServletResponse res = (HttpServletResponse) response;
		// 获得ServletContext
		ServletContext context = config.getServletContext();
		// Map<静态页面名称(不包含后缀),含后缀>
		Map<String, String> staticPageMap = (Map<String, String>) context.getAttribute("staticPageMap");
		if (staticPageMap == null) {
			staticPageMap = new HashMap<String, String>();
			context.setAttribute("staticPageMap", staticPageMap);
		}
		
		String category = req.getParameter("category");
		String key = "book_" + category;
		// 存在静态页面,就重定向到静态页面
		if (staticPageMap.containsKey(key)) {
			String staticPageName = staticPageMap.get(key);
			res.sendRedirect(context.getContextPath() + "/staticPages/" + staticPageName);
			return;
		}
		// 不存在静态页面，就创建
		String newStaticPageName = key + ".html";
		String newStaticPagePath = context.getRealPath("/staticPages/" + newStaticPageName);
		MyResponse myRes = new MyResponse(res, newStaticPagePath);
		staticPageMap.put(key, newStaticPageName);
		chain.doFilter(req, myRes);

	}

	public void destroy() {

	}

}

MyResponse.java

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package zh.response.demo;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;

import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;

public class MyResponse extends HttpServletResponseWrapper {

	private HttpServletResponse res;
	private PrintWriter writer;
	
	public MyResponse(HttpServletResponse response, String path) throws FileNotFoundException, UnsupportedEncodingException{
		
		super(response);
		this.res = response;
		writer = new PrintWriter(path, "utf-8");
		
	}
	
	@Override
	public PrintWriter getWriter() throws IOException {
		return writer;
	}
	
	public void close() {
		writer.close();
	}
	
}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>Javaweb01</display-name>
  <servlet>
    <servlet-name>BookServlet</servlet-name>
    <servlet-class>zh.response.demo.BookServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>BookServlet</servlet-name>
    <url-pattern>/BookServlet</url-pattern>
  </servlet-mapping>
  
  <filter>
  	<filter-name>BookFilter</filter-name>
  	<filter-class>zh.response.demo.BookFilter</filter-class>
  </filter>
  <filter-mapping>
  	<filter-name>BookFilter</filter-name>
  	<url-pattern>/BookServlet</url-pattern>
  </filter-mapping>
  
</web-app>

JavaWeb之Filter实现页面静态化

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