案例25-servlet的抽取

1 product模块的抽取版本一

1 ProductServlet代码

抽取之后，原来对应的IndexServlet，ProductListByCidServlet等都可以删除。对应的web.xml里面的配置文件也需要删除。

然后就是需要修改原来页面中执行对应servlet的代码。

package www.test.web.servlet;

import java.io.IOException;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

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

import com.google.gson.Gson;

import redis.clients.jedis.Jedis;
import www.test.domain.Category;
import www.test.domain.Product;
import www.test.service.ProductService;
import www.test.utils.JedisPoolUtils;
import www.test.vo.PageBean;

public class ProductServlet extends HttpServlet {

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

        //获得请求的哪个方法method
        String methodName = request.getParameter("method");
         //防止非空，将productListByCid放在前面，这样就能避免    
        if("productListByCid".equals(methodName)){
            productListByCid(request,response);
        }else if("categoryList".equals(methodName)){
            categoryList(request,response);
        }else if("index".equals(methodName)){
            index(request,response);
        }else if("productInfo".equals(methodName)){
            productInfo(request,response);
        }
        
    }

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

    // 模块中的方法是通过方法名进行区分的

    // 1 显示商品类别的功能
    public void categoryList(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        ProductService service = new ProductService();

        // 先从缓存中查询categoryList 如果有直接使用 没有在从数据库中查询 存到缓存中
        // 1、获得jedis对象 连接redis数据库
        Jedis jedis = JedisPoolUtils.getJedis();
        String categoryListJson = jedis.get("categoryListJson");

        // 2、判断categoryListJson是否为空
        if (categoryListJson == null) {
            System.out.println("缓存没有数据 查询数据库");

            // 准备分类数据
            List<Category> categoryList = null;
            try {
                categoryList = service.findAllCategory();
            } catch (SQLException e) {

                e.printStackTrace();
            }
            // 使用转换工具将categoryList转换成json格式
            Gson gson = new Gson();
            categoryListJson = gson.toJson(categoryList);
            // 将从数据库中获得的categoryListJson存储到缓存中
            jedis.set("categoryListJson", categoryListJson);
        }

        // 将转换后的json格式字符串写出
        // 写出前先解决乱码问题
        response.setContentType("text/html;charset=UTF-8");
        response.getWriter().write(categoryListJson);
    }

    // 2 显示首页的功能
    public void index(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        ProductService service = new ProductService();

        // 获取热门商品-----List<Product>
        List<Product> hotProductList = null;
        try {
            hotProductList = service.findHotProductList();
        } catch (SQLException e) {

            e.printStackTrace();
        }

        // 获取最新商品-----List<Product>
        List<Product> newProductList = null;
        try {
            newProductList = service.findNewProductList();
        } catch (SQLException e) {

            e.printStackTrace();
        }

        // 准备分类数据
        /*
         * List<Category> categoryList =null; try { categoryList =
         * service.findAllCategory(); } catch (SQLException e) {
         * 
         * e.printStackTrace(); } request.setAttribute("categoryList",
         * categoryList);
         */

        // 将获取的数据存入request域
        request.setAttribute("hotProductList", hotProductList);
        request.setAttribute("newProductList", newProductList);

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

    }

    
    
    // 3 显示商品的详细信息的功能
    public void productInfo(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        // 获取cid和当前页
        String cid = request.getParameter("cid");
        String currentPage = request.getParameter("currentPage");

        // 获取pid
        String pid = request.getParameter("pid");

        // 传递给service层并调取service层的方法
        ProductService service = new ProductService();
        Product product = null;
        try {
            product = service.findProductByPid(pid);
        } catch (SQLException e) {

            e.printStackTrace();
        }

        // 存储到request域中
        request.setAttribute("product", product);
        request.setAttribute("cid", cid);
        request.setAttribute("currentPage", currentPage);

        // 获取客户端携带的cookie----获得名字是pids的cookie
        String pids = pid;
        Cookie[] cookies = request.getCookies();
        if (cookies != null) {
            for (Cookie cookie : cookies) {
                if ("pids".equals(cookie.getName())) {
                    pids = cookie.getValue();
                    // 1-3-2 本次访问的商品的pid是8----->8-1-3-2
                    // 1-3-2 本次访问的商品的pid是3----->3-1-2
                    // 1-3-2 本次访问的商品的pid是1----->2-1-3
                    // 将pids拆成一个数组
                    String[] split = pids.split("-");// {3,1,2}
                    // 数组转换成集合
                    List<String> asList = Arrays.asList(split);// [3,1,2]
                    LinkedList<String> list = new LinkedList<String>(asList); // [3,1,2]

                    // 判断集合中是否存在当前的pid
                    /*
                     * if(list.contains(pid)){ //包含当前查看的商品的pid //先删掉然后放在头上
                     * list.remove(pid); list.addFirst(pid); }else{
                     * //不包含当前查看的商品的pid 直接将该pid放在头上 list.addFirst(pid); }
                     */

                    // 上面代码的优化
                    // 不管包不包含都需要放到头上
                    if (list.contains(pid)) {
                        // 包含当前查看的商品的pid
                        list.remove(pid);
                    }
                    list.addFirst(pid);

                    // 将[3,1,2]转成3-1-2字符串
                    StringBuffer sb = new StringBuffer();
                    for (int i = 0; i < list.size() && i < 7; ++i) {
                        sb.append(list.get(i));
                        sb.append("-"); // 3-1-2-
                    }
                    // 去掉3-1-2-后面的-
                    // substring包含头不包含尾
                    pids = sb.substring(0, sb.length() - 1);

                }
            }
        }

        // 创建cookie回写
        Cookie cookie_pids = new Cookie("pids", pids);
        cookie_pids.setMaxAge(60 * 60); // 单位为秒 设置cookie的存储事件一个小时
        // 设置cookie的携带路径
        cookie_pids.setPath(request.getContextPath());
        // 将cookie_pids写回去
        response.addCookie(cookie_pids);

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

    }
    
    
    
    // 4 根据商品的类别获得商品的列表
    public void productListByCid(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //获取cid
        String cid = request.getParameter("cid");
        String currentPageStr = request.getParameter("currentPage");
        if(currentPageStr == null){
            currentPageStr = "1";
        }
        int currentPage = Integer.parseInt(currentPageStr);
        int currentCount =12;
        //根据cid查询商品
        ProductService service = new ProductService();
        PageBean<Product> pageBean = service.findProductListByCid(cid,currentPage,currentCount);
        
        request.setAttribute("pageBean", pageBean);
        request.setAttribute("cid", cid);
        
        //定义一个集合记录历史商品信息的集合
        List<Product> historyProductList = new ArrayList<Product>();
        
        
        //获取客户端携带的名字叫pids的cookie
        Cookie[] cookies = request.getCookies();
        if(cookies!=null){
            for (Cookie cookie : cookies) {
                if("pids".equals(cookie.getName())){
                    String pids = cookie.getValue(); //3-1-2
                    String[] split = pids.split("-");
                    for(String pid:split){
                        Product product =null;
                        try {
                            product = service.findProductByPid(pid);
                            historyProductList.add(product);
                        } catch (SQLException e) {
                            
                            e.printStackTrace();
                        }
                    }
                }
            }
        }
        
        //将历史记录的集合放到域中
        request.setAttribute("historyProductList", historyProductList);
        
        //转发
        request.getRequestDispatcher("/product_list.jsp").forward(request, response);
    }

}

2 页面中代码的修改

将原来访问的servlet改成访问ProductServlet，需要访问的方法以get的方式提交过去。

2 product模块的抽取版本二

版本二中对ProductServlet中方法的调用进行抽取。

1 ProductServlet代码

package www.test.web.servlet;

import java.io.IOException;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

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

import com.google.gson.Gson;

import redis.clients.jedis.Jedis;
import www.test.domain.Category;
import www.test.domain.Product;
import www.test.service.ProductService;
import www.test.utils.JedisPoolUtils;
import www.test.vo.PageBean;

public class ProductServlet extends BaseServlet {

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

        //获得请求的哪个方法method
        String methodName = request.getParameter("method");
         //防止非空，将productListByCid放在前面，这样就能避免    
        if("productListByCid".equals(methodName)){
            productListByCid(request,response);
        }else if("categoryList".equals(methodName)){
            categoryList(request,response);
        }else if("index".equals(methodName)){
            index(request,response);
        }else if("productInfo".equals(methodName)){
            productInfo(request,response);
        }
        
    }

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

    // 模块中的方法是通过方法名进行区分的

    // 1 显示商品类别的功能
    public void categoryList(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        ProductService service = new ProductService();

        // 先从缓存中查询categoryList 如果有直接使用 没有在从数据库中查询 存到缓存中
        // 1、获得jedis对象 连接redis数据库
        Jedis jedis = JedisPoolUtils.getJedis();
        String categoryListJson = jedis.get("categoryListJson");

        // 2、判断categoryListJson是否为空
        if (categoryListJson == null) {
            System.out.println("缓存没有数据 查询数据库");

            // 准备分类数据
            List<Category> categoryList = null;
            try {
                categoryList = service.findAllCategory();
            } catch (SQLException e) {

                e.printStackTrace();
            }
            // 使用转换工具将categoryList转换成json格式
            Gson gson = new Gson();
            categoryListJson = gson.toJson(categoryList);
            // 将从数据库中获得的categoryListJson存储到缓存中
            jedis.set("categoryListJson", categoryListJson);
        }

        // 将转换后的json格式字符串写出
        // 写出前先解决乱码问题
        response.setContentType("text/html;charset=UTF-8");
        response.getWriter().write(categoryListJson);
    }

    // 2 显示首页的功能
    public void index(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        ProductService service = new ProductService();

        // 获取热门商品-----List<Product>
        List<Product> hotProductList = null;
        try {
            hotProductList = service.findHotProductList();
        } catch (SQLException e) {

            e.printStackTrace();
        }

        // 获取最新商品-----List<Product>
        List<Product> newProductList = null;
        try {
            newProductList = service.findNewProductList();
        } catch (SQLException e) {

            e.printStackTrace();
        }

        // 准备分类数据
        /*
         * List<Category> categoryList =null; try { categoryList =
         * service.findAllCategory(); } catch (SQLException e) {
         * 
         * e.printStackTrace(); } request.setAttribute("categoryList",
         * categoryList);
         */

        // 将获取的数据存入request域
        request.setAttribute("hotProductList", hotProductList);
        request.setAttribute("newProductList", newProductList);

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

    }

    
    
    // 3 显示商品的详细信息的功能
    public void productInfo(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        // 获取cid和当前页
        String cid = request.getParameter("cid");
        String currentPage = request.getParameter("currentPage");

        // 获取pid
        String pid = request.getParameter("pid");

        // 传递给service层并调取service层的方法
        ProductService service = new ProductService();
        Product product = null;
        try {
            product = service.findProductByPid(pid);
        } catch (SQLException e) {

            e.printStackTrace();
        }

        // 存储到request域中
        request.setAttribute("product", product);
        request.setAttribute("cid", cid);
        request.setAttribute("currentPage", currentPage);

        // 获取客户端携带的cookie----获得名字是pids的cookie
        String pids = pid;
        Cookie[] cookies = request.getCookies();
        if (cookies != null) {
            for (Cookie cookie : cookies) {
                if ("pids".equals(cookie.getName())) {
                    pids = cookie.getValue();
                    // 1-3-2 本次访问的商品的pid是8----->8-1-3-2
                    // 1-3-2 本次访问的商品的pid是3----->3-1-2
                    // 1-3-2 本次访问的商品的pid是1----->2-1-3
                    // 将pids拆成一个数组
                    String[] split = pids.split("-");// {3,1,2}
                    // 数组转换成集合
                    List<String> asList = Arrays.asList(split);// [3,1,2]
                    LinkedList<String> list = new LinkedList<String>(asList); // [3,1,2]

                    // 判断集合中是否存在当前的pid
                    /*
                     * if(list.contains(pid)){ //包含当前查看的商品的pid //先删掉然后放在头上
                     * list.remove(pid); list.addFirst(pid); }else{
                     * //不包含当前查看的商品的pid 直接将该pid放在头上 list.addFirst(pid); }
                     */

                    // 上面代码的优化
                    // 不管包不包含都需要放到头上
                    if (list.contains(pid)) {
                        // 包含当前查看的商品的pid
                        list.remove(pid);
                    }
                    list.addFirst(pid);

                    // 将[3,1,2]转成3-1-2字符串
                    StringBuffer sb = new StringBuffer();
                    for (int i = 0; i < list.size() && i < 7; ++i) {
                        sb.append(list.get(i));
                        sb.append("-"); // 3-1-2-
                    }
                    // 去掉3-1-2-后面的-
                    // substring包含头不包含尾
                    pids = sb.substring(0, sb.length() - 1);

                }
            }
        }

        // 创建cookie回写
        Cookie cookie_pids = new Cookie("pids", pids);
        cookie_pids.setMaxAge(60 * 60); // 单位为秒 设置cookie的存储事件一个小时
        // 设置cookie的携带路径
        cookie_pids.setPath(request.getContextPath());
        // 将cookie_pids写回去
        response.addCookie(cookie_pids);

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

    }
    
    
    
    // 4 根据商品的类别获得商品的列表
    public void productListByCid(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //获取cid
        String cid = request.getParameter("cid");
        String currentPageStr = request.getParameter("currentPage");
        if(currentPageStr == null){
            currentPageStr = "1";
        }
        int currentPage = Integer.parseInt(currentPageStr);
        int currentCount =12;
        //根据cid查询商品
        ProductService service = new ProductService();
        PageBean<Product> pageBean = service.findProductListByCid(cid,currentPage,currentCount);
        
        request.setAttribute("pageBean", pageBean);
        request.setAttribute("cid", cid);
        
        //定义一个集合记录历史商品信息的集合
        List<Product> historyProductList = new ArrayList<Product>();
        
        
        //获取客户端携带的名字叫pids的cookie
        Cookie[] cookies = request.getCookies();
        if(cookies!=null){
            for (Cookie cookie : cookies) {
                if("pids".equals(cookie.getName())){
                    String pids = cookie.getValue(); //3-1-2
                    String[] split = pids.split("-");
                    for(String pid:split){
                        Product product =null;
                        try {
                            product = service.findProductByPid(pid);
                            historyProductList.add(product);
                        } catch (SQLException e) {
                            
                            e.printStackTrace();
                        }
                    }
                }
            }
        }
        
        //将历史记录的集合放到域中
        request.setAttribute("historyProductList", historyProductList);
        
        //转发
        request.getRequestDispatcher("/product_list.jsp").forward(request, response);
    }

}

2 BaseServlet代码

package www.test.web.servlet;

import java.io.IOException;
import java.lang.reflect.Method;

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

public class BaseServlet extends HttpServlet {

    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
        //解决乱码问题
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        
        try {
            // 1 获得请求的method方法
            String methodName = request.getParameter("method");
            
            // 2获得当前被访问的对象的字节码对象
            Class clazz = this.getClass();  //ProductServlet.class --- UserServlet.class
            
            // 3 获取当前字节码对象中指定的方法
            Method method = clazz.getMethod(methodName,HttpServletRequest.class,HttpServletResponse.class);
            
            // 4 执行相应的方法
            method.invoke(this, request,response);
        } catch (Exception e) {
            
            e.printStackTrace();
        }
    }

}

 其他代码和版本一一样