Java Web程序设计第9章课后第1题

RC Kanashii

于 2021-11-19 13:25:45 发布

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文章标签： javaweb java tomcat

本文链接：https://blog.youkuaiyun.com/u013592576/article/details/121420183

版权

编写图书模糊查询界面，输入图书名称的模糊资料，在界面下方显示图书信息，要求提交给Servlet完成。

解析

在数据库中建个表
在这里插入图片描述
然后简单地弄一个book类

public class book {
    public String id;
    public String name;
    public double price;

    public book(String id, String name, double price) {
        this.id = id;
        this.name = name;
        this.price = price;
    }
}

在search.jsp中先搭个框架

<form action="一会要创建的Servlet" method="post">
    请输入要查找的书名：<input name="name" type="text">
    <input type="submit" value="查询">
</form>
<table>
    <tr>
        <th>图书ID</th>
        <th>图书名称</th>
        <th>图书价格</th>
        <th>操作</th>
    </tr>
    <!-- 这里一会要插入JSP代码 -->
</table>

新建一个FuzzyLookupServlet

@WebServlet(name = "FuzzyLookupServlet", urlPatterns = {"/fuzzyLookupServlet"})
public class FuzzyLookupServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 处理响应乱码
        response.setContentType("text/html;charset=utf-8");

        // 处理请求乱码
        request.setCharacterEncoding("utf-8");

        String name = request.getParameter("name");
        if (name != null) {
            try {
                // 1、导入驱动jar包
                // 2、注册驱动
                Class.forName("com.mysql.cj.jdbc.Driver");
                // 3、获取数据库的连接对象
                Connection conn = DriverManager.getConnection("你的数据库", "用户名", "你的密码");
                // 4、定义sql语句
                String sql = "select * from book where name like '%" + name + "%'";
                // 5、获取执行sql语句的对象
                PreparedStatement ps = conn.prepareStatement(sql);
                // 6、执行sql并接收返回结果
                ResultSet rs = ps.executeQuery(sql);
                // 7、处理结果
                ArrayList<book> res = new ArrayList<book>();
                while (rs.next()) {
                    res.add(new book(rs.getString(1), rs.getString(2), rs.getDouble(3)));
                }
                HttpSession session = request.getSession();
                session.setAttribute("result", res);  // 把查询到的结果存放在session中
                // 8、释放资源
                ps.close();
                conn.close();
                // 9、跳转
                request.getRequestDispatcher("/chapter9/9_1/search.jsp").forward(request, response);  // 查询完毕后要返回到search.jsp
            } catch (ClassNotFoundException | SQLException e) {
                e.printStackTrace();
            }
        }
    }

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

回到search.jsp，先把form action补齐，如

<form action="/JavaWebCDUT/fuzzyLookupServlet" method="post">

然后补全JSP代码

<%
    ArrayList<book> res = (ArrayList<book>) session.getAttribute("result");
    if (res != null) {
%>
<table>
    <tr>
        <th>图书ID</th>
        <th>图书名称</th>
        <th>图书价格</th>
        <th>操作</th>
    </tr>
    <%
            for (book b : res) {
                out.print("<tr>");
                out.print("<td>" + b.id + "</td>");
                out.print("<td>" + b.name + "</td>");
                out.print("<td>" + b.price + "</td>");
                out.print(String.format("<td><a href=\"/JavaWebCDUT/addToCartServlet?id=%s\">添加到购物车</a></td>", b.id));
                out.print("</tr>");
            }
        }
    %>

完整代码

search.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page import="chapter9.book" %>
<%@ page import="java.util.ArrayList" %>
<html>
<head>
    <title>模糊查询</title>
</head>
<body>
<form action="/JavaWebCDUT/fuzzyLookupServlet" method="post">
    请输入要查找的书名：<input name="name" type="text">
    <input type="submit" value="查询">
</form>
<%
    ArrayList<book> res = (ArrayList<book>) session.getAttribute("result");
    if (res != null) {
%>
<table>
    <tr>
        <th>图书ID</th>
        <th>图书名称</th>
        <th>图书价格</th>
        <th>操作</th>
    </tr>
    <%
            for (book b : res) {
                out.print("<tr>");
                out.print("<td>" + b.id + "</td>");
                out.print("<td>" + b.name + "</td>");
                out.print("<td>" + b.price + "</td>");
                out.print(String.format("<td><a href=\"/JavaWebCDUT/addToCartServlet?id=%s\">添加到购物车</a></td>", b.id));
                out.print("</tr>");
            }
        }
    %>
</table>
</body>
</html>

FuzzyLookupServlet.java

package chapter9.servlet;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.sql.*;
import java.util.ArrayList;

import chapter9.book;

import static java.lang.System.out;

@WebServlet(name = "FuzzyLookupServlet", urlPatterns = {"/fuzzyLookupServlet"})
public class FuzzyLookupServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 处理响应乱码
        response.setContentType("text/html;charset=utf-8");

        // 处理请求乱码
        request.setCharacterEncoding("utf-8");

        String name = request.getParameter("name");
        if (name != null) {
            try {
                // 1、导入驱动jar包
                // 2、注册驱动
                Class.forName("com.mysql.cj.jdbc.Driver");
                // 3、获取数据库的连接对象
                Connection conn = DriverManager.getConnection("你的数据库", "用户名", "你的密码");
                // 4、定义sql语句
                String sql = "select * from book where name like '%" + name + "%'";
                // 5、获取执行sql语句的对象
                PreparedStatement ps = conn.prepareStatement(sql);
                // 6、执行sql并接收返回结果
                ResultSet rs = ps.executeQuery(sql);
                // 7、处理结果
                ArrayList<book> res = new ArrayList<book>();
                while (rs.next()) {
                    res.add(new book(rs.getString(1), rs.getString(2), rs.getDouble(3)));
                }
                HttpSession session = request.getSession();
                session.setAttribute("result", res);
                // 8、释放资源
                ps.close();
                conn.close();
                // 9、跳转
                request.getRequestDispatcher("/chapter9/9_1/search.jsp").forward(request, response);
            } catch (ClassNotFoundException | SQLException e) {
                e.printStackTrace();
            }
        }
    }

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

book.java

package chapter9;

public class book {
    public String id;
    public String name;
    public double price;

    public book(String id, String name, double price) {
        this.id = id;
        this.name = name;
        this.price = price;
    }
}

AddToCartServlet,java

package chapter9.servlet;

import chapter9.book;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.awt.*;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.*;
import java.util.ArrayList;

@WebServlet(name = "addToCartServlet", urlPatterns = {"/addToCartServlet"})
public class AddToCartServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 处理响应乱码
        response.setContentType("text/html;charset=utf-8");

        // 处理请求乱码
        request.setCharacterEncoding("utf-8");

        String id = request.getParameter("id");
        if (id != null) {
            try {
                // 1、导入驱动jar包
                // 2、注册驱动
                Class.forName("com.mysql.cj.jdbc.Driver");
                // 3、获取数据库的连接对象
                Connection conn = DriverManager.getConnection("你的数据库", "用户名", "你的密码");
                // 4、定义sql语句
                String sql = "select * from book where id = ?";
                // 5、获取执行sql语句的对象
                PreparedStatement ps = conn.prepareStatement(sql);
                // 6、执行sql并接收返回结果
                ps.setString(1, id);
                ResultSet rs = ps.executeQuery();
                // 7、处理结果
                HttpSession session = request.getSession();
                ArrayList<book> cart = (ArrayList<book>) session.getAttribute("cart");
                if (cart == null){
                    cart = new ArrayList<book>();
                }
                while (rs.next()) {
                    cart.add(new book(rs.getString(1), rs.getString(2), rs.getDouble(3)));
                }
                session.setAttribute("cart", cart);
                // 8、释放资源
                ps.close();
                conn.close();
                // 9、跳转
                session.setAttribute("addStatus", true);
                System.out.println("添加成功");
                PrintWriter out = response.getWriter();
                out.print("<script>alert('添加成功!');window.location.href='chapter9/9_1/search.jsp'</script>");
            } catch (ClassNotFoundException | SQLException e) {
                e.printStackTrace();
            }
        }
    }

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