使用Servlet完成条件查询

本文讲解使用Servlet如何实现条件查询(支持模糊搜索)。使用的数据库是MySQL5.7版本。

1 创建表和导入数据

在MySQL的test数据库中执行以下SQL来建立表和导入测试数据:

CREATE TABLE `customer` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(50) DEFAULT NULL,
  `gender` varchar(20) DEFAULT NULL,
  `telephone` varchar(100) DEFAULT NULL,
  `address` varchar(100) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=9 DEFAULT CHARSET=utf8;

/*Data for the table `customer` */

insert  into `customer`(`id`,`name`,`gender`,`telephone`,`address`) values (1,'张三','男','021-3654987','北京市海淀区'),(2,'李四','男','021-3332222','广州市天河区'),(3,'王五','男','020-1112234','广州市番禺区'),(4,'陈六','女','020-4443335','广州市越秀区'),(5,'测试账户2','男','020-232221222','广州番禺区'),(6,'张祥','男','020-232221222','广州市越秀区');

最终效果如下:

2 编写index.jsp页面

index.jsp用于输入搜索条件:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>一点教程网-使用Servlet完成条件查询</title>
</head>
<body>
<h1>使用Servlet完成条件查询</h1>
<form action="Search" method="post">
    请输入客户名称:<input type="text" name="name"/><br/>
    <input type="submit" value="搜索"/>
</form>
</body>
</html>

3 编写SearchServlet

SearchServlet用于完成从数据库的查询功能:

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.*;

/**
 * 一点教程网 - http://www.yiidian.com
 */
public class SearchServlet extends HttpServlet {

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        PrintWriter out = response.getWriter();

        String name=request.getParameter("name");

        try{
            Class.forName("com.mysql.jdbc.Driver");
            Connection con= DriverManager.getConnection(
                    "jdbc:mysql://localhost:3306/test","root","root");

            PreparedStatement ps=con.prepareStatement("select * from customer where name like ?");
            ps.setString(1,"%"+name+"%");

            out.print("<table width=50% border=1>");
            out.print("<caption>以下为搜索结果:</caption>");

            ResultSet rs=ps.executeQuery();

            /* 显示结果*/
            ResultSetMetaData rsmd=rs.getMetaData();
            int total=rsmd.getColumnCount();
            out.print("<tr>");
            for(int i=1;i<=total;i++)
            {
                out.print("<th>"+rsmd.getColumnName(i)+"</th>");
            }

            out.print("</tr>");


            while(rs.next())
            {
                out.print("<tr><td>"+rs.getInt(1)+"</td><td>"+rs.getString(2)+ ""
                       +" </td><td>"+rs.getString(3)+"</td><td>"+rs.getString(4)+"</td><td>"+rs.getString(5)+"</td></tr>");

            }

            out.print("</table>");

        }catch (Exception e2) {
            e2.printStackTrace();
        }finally{
            out.close();
        }
    }

}

4 配置web.xml

web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">

    <servlet>
        <servlet-name>SearchServlet</servlet-name>
        <servlet-class>SearchServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>SearchServlet</servlet-name>
        <url-pattern>/Search</url-pattern>
    </servlet-mapping>
    
</web-app>

5 运行测试

先访问主页,http://localhost:8080/,如下:
输入搜索条件“张”,点击“搜索”,结果如下:


本案例需要在lib目录导入mysql驱动程序,点击下面链接下载:

下载mysql-connector-java-5.1.40.jar

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