ipconfig /flushdns

 netsh int ip rese

 netsh winsock reset

 CREATE TABLE customer (

     id INT,

     customer_name VARCHAR(10) NOT NULL UNIQUE,

     customer_address VARCHAR(20),

     customer_phone VARCHAR(10),

     customer_thing VARCHAR(20)

 )

 <?xml version="1.0" encoding="UTF-8" ?>

 <c3p0-config>

     <named-config name="mvcC3p0">

         <property name="user">root</property>

         <property name="password">zy961029</property>

         <property name="driverClass">com.mysql.jdbc.Driver</property>

         <property name="jdbcUrl">jdbc:mysql:///sh_db</property>

         <property name="maxStatements">1</property>

         <property name="maxStatementsPerConnection">5</property>

     </named-config>

 </c3p0-config>

 package com.java.homework.db;

 import com.mchange.v2.c3p0.ComboPooledDataSource;

 import javax.sql.DataSource;

 import java.sql.Connection;

 import java.sql.SQLException;

 /**

  * 获取数据库连接和释放数据库连接的工具类

  */

 public class JDBCTools {

     //    由于静态代码块只执行一次，所以只会创建一份 dataSource，达到节省资源的目的，并且将工具类方法声明为静态的，可由类直接调用

     private static DataSource dataSource = null;

     static {

         dataSource = new ComboPooledDataSource("mvcC3p0");

     }

     public static Connection getConnection() {

         Connection connection = null;

         try {

             connection = dataSource.getConnection();

         } catch (SQLException e) {

             e.printStackTrace();

         }

         return connection;

     }

     public static void reledse(Connection connection) {

         try {

             if (connection != null) {

                 connection.close();

             }

         } catch (SQLException e) {

             e.printStackTrace();

         }

     }

 }

 package com.java.homework.dao;

 import com.java.homework.db.JDBCTools;

 import org.apache.commons.dbutils.QueryRunner;

 import org.apache.commons.dbutils.handlers.BeanHandler;

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

 import org.apache.commons.dbutils.handlers.ScalarHandler;

 import java.lang.reflect.ParameterizedType;

 import java.lang.reflect.Type;

 import java.sql.Connection;

 import java.sql.SQLException;

 import java.util.List;

 /**

  * 封装 CRUD 的方法，

  * 利用 C3P0 数据库连接池和 DBUtils 连接数据库

  * 注意 type 的获取方法，直接在构造器中初始化，为 BeanHandler、BeanListHandler 传值

  * @param <T> 当前 DAO 处理的实体类类型

  */

 public class DAO<T> {

     private QueryRunner queryRunner;

     private Class<T> type;

     /*

     * 构造器直接初始化 queryRunner 对象和 BeanHandler 和 BeanListHandler 所需要的 Class 对象（利用反射创建，使其更有可扩展性）

     * */

     public DAO() {

         queryRunner = new QueryRunner();

         Type superclass = getClass().getGenericSuperclass();

         if (superclass instanceof  ParameterizedType) {

             ParameterizedType parameterizedType = (ParameterizedType) superclass;

             Type[] args = parameterizedType.getActualTypeArguments();

             if (args != null && args.length > 0) {

                 if (args[0] instanceof Class) {

                     type = (Class<T>) args[0];

                 }

             }

         }

     }

     /*

     * 封装了增删改的方法

     * */

     public void update(String sql, Object...args) {

         Connection connection = JDBCTools.getConnection();

         try {

             queryRunner.update(connection, sql, args );

         } catch (SQLException e) {

             e.printStackTrace();

         }finally {

             JDBCTools.reledse(connection);

         }

     }

     /*

     获取单个值，比如某一列的某一个值，或 count 值

      */

     public Object getForValue(String sql, Object...args){

         Connection connection = JDBCTools.getConnection();

         Object value = null;

         try {

             value = queryRunner.query(connection, sql, new ScalarHandler(), args);

         } catch (SQLException e) {

             e.printStackTrace();

         } finally {

             JDBCTools.reledse(connection);

         }

         return value;

     }

     /*

     *  获取多行值，封装为 List 返回

     * */

     public List<T> getForList(String sql, Object...args) {

         Connection connection = JDBCTools.getConnection();

         List<T> list = null;

         try {

             list = queryRunner.query(connection, sql, new BeanListHandler<T>(type),args);

         } catch (SQLException e) {

             e.printStackTrace();

         }finally {

             JDBCTools.reledse(connection);

         }

         return list;

     }

     /*

     * 获取单列值

     * */

     public T get(String sql, Object...args){

         Connection connection = JDBCTools.getConnection();

         T entity = null;

         try {

             entity = queryRunner.query(connection, sql, new BeanHandler<T>(type), args);

         } catch (SQLException e) {

             e.printStackTrace();

         }finally {

             JDBCTools.reledse(connection);

         }

         return entity;

     }

 }

 package com.java.homework.domain;

 public class Customer {

     private Integer id;

     private String customerName;

     private String customerAddress;

     private String customerPhone;

     private String customerThing;

     @Override

     public String toString() {

         return "Customer{" +

                 "id=" + id +

                 ", customerName='" + customerName + '\'' +

                 ", customerAddress='" + customerAddress + '\'' +

                 ", customerPhone='" + customerPhone + '\'' +

                 ", customerThing='" + customerThing + '\'' +

                 '}';

     }

     public Integer getId() {

         return id;

     }

     public void setId(Integer id) {

         this.id = id;

     }

     public String getCustomerName() {

         return customerName;

     }

     public void setCustomerName(String customerName) {

         this.customerName = customerName;

     }

     public String getCustomerAddress() {

         return customerAddress;

     }

     public void setCustomerAddress(String customerAddress) {

         this.customerAddress = customerAddress;

     }

     public String getCustomerPhone() {

         return customerPhone;

     }

     public void setCustomerPhone(String customerPhone) {

         this.customerPhone = customerPhone;

     }

     public String getCustomerThing() {

         return customerThing;

     }

     public void setCustomerThing(String customerThing) {

         this.customerThing = customerThing;

     }

 //   为了方便测试我们写一个带参的构造器

     public Customer(Integer id, String customerName, String customerAddress, String customerPhone, String customerThing) {

         this.id = id;

         this.customerName = customerName;

         this.customerAddress = customerAddress;

         this.customerPhone = customerPhone;

         this.customerThing = customerThing;

     }

 //   由于需要利用反射，所以必须写无参构造器

     public Customer() {

     }

 }

 package com.java.homework.dao;

 import com.java.homework.criteria.CriteriaCustomer;

 import com.java.homework.domain.Customer;

 import java.sql.SQLException;

 import java.util.List;

 /**

  * 针对本数据表封装所需功能的方法，将其封装为一个接口

  */

 public interface CustomerDao {

 //    获得数据表的所有值

     List<Customer> getAll();

 //    根据 id 获取单行

     Customer get(Integer id) throws SQLException;

 //    执行删除操作

     void delete(Integer id) throws SQLException;

 //    执行保存操作

     void save(Customer customer) throws SQLException;

 //    根据 customerName 获取与之匹配行的行数

     Long getCountWithName(String name1) throws SQLException;

 //    模糊查询，将查询条件封装为一个单类，CriteriaCustomer。因为有些查询条件并不是像本案例一样和 Customer 基类一样

     List<Customer> getListOfLike(CriteriaCustomer criteriaCustomer);

 //    执行更新操作

     void update(Customer customer, Integer id);

 //    获取 customerName

     Object getCusName(Integer id);

 }

 package com.java.homework.daoImpl;

 import com.java.homework.criteria.CriteriaCustomer;

 import com.java.homework.dao.CustomerDao;

 import com.java.homework.dao.DAO;

 import com.java.homework.domain.Customer;

 import java.sql.SQLException;

 import java.util.List;

 /**

  * 继承 DAO 类实现 CustomerDao 接口

  */

 public class CustomerDaoImpl extends DAO<Customer> implements CustomerDao {

     @Override

     public List<Customer> getAll() {

         String sql = "SELECT id, customer_name customerName, customer_address customerAddress, customer_phone customerPhone," +

                 "customer_thing customerThing FROM customer";

         List<Customer> customerList;

         customerList = getForList(sql);

         return customerList;

     }

     @Override

     public Customer get(Integer id) throws SQLException {

         String sql = "SELECT id,customer_name customerName, customer_address customerAddress, customer_phone customerPhone," +

                 "customer_thing customerThing FROM customer WHERE id=?";

         return get(sql, id);

     }

     @Override

     public void delete(Integer id) throws SQLException {

         String sql = "DELETE FROM customer WHERE id=?";

         update(sql, id);

     }

     @Override

     public void save(Customer customer) throws SQLException {

         String sql = "INSERT INTO customer(customer_name, customer_address, customer_phone, customer_thing) VALUES(" +

                 "?,?,?,?)";

         update(sql, customer.getCustomerName(), customer.getCustomerAddress(), customer.getCustomerPhone(), customer.getCustomerThing());

     }

     @Override

     public Long getCountWithName(String name) throws SQLException {

         Long value;

         String sql = "SELECT COUNT(id) FROM customer WHERE customer_name=?";

         value = (Long) getForValue(sql, name);

         return value;

     }

     @Override

     public List<Customer> getListOfLike(CriteriaCustomer criteriaCustomer) {

         String sql = "SELECT id, customer_name customerName, customer_address customerAddress, customer_phone customerPhone," +

                 "customer_thing customerThing FROM customer WHERE customer_name LIKE ? AND customer_address LIKE ? AND " +

                 "customer_phone LIKE ? AND customer_thing LIKE ?";

         return getForList(sql, criteriaCustomer.getCustomerName(), criteriaCustomer.getCustomerAddress(), criteriaCustomer

                                 .getCustomerPhone(), criteriaCustomer.getCustomerThing());

     }

     @Override

     public void update(Customer customer, Integer id) {

         String sql = "UPDATE customer SET customer_name=?, customer_address=?, customer_phone=?," +

                 " customer_thing=? WHERE id=?";

         update(sql, customer.getCustomerName(), customer.getCustomerAddress(), customer.getCustomerPhone(), customer.getCustomerThing(), id);

     }

     @Override

     public Object getCusName(Integer id) {

         String sql = "SELECT customer_name customerName FROM customer WHERE id=?";

         return getForValue(sql, id);

     }

 }

 package homeworl.test;

 import com.java.homework.criteria.CriteriaCustomer;

 import com.java.homework.dao.CustomerDao;

 import com.java.homework.daoImpl.CustomerDaoImpl;

 import com.java.homework.db.JDBCTools;

 import com.java.homework.domain.Customer;

 import org.junit.Test;

 import java.sql.Connection;

 import java.sql.SQLException;

 import java.util.List;

 /**

  * Created by shkstart on 2017/11/13.

  */

 public class TestCustomerDaoImpl {

     private CustomerDao customerDao = new CustomerDaoImpl();

     @Test

     public void testGetForList() {

         List<Customer> customerList = customerDao.getAll();

         System.out.println(customerList);

     }

     @Test

     public void testGetConnection() {

         Connection connection = JDBCTools.getConnection();

         System.out.println(connection);

     }

     @Test

     public void testGet() throws SQLException {

         Customer customer = customerDao.get(1);

         System.out.println(customer);

     }

     @Test

     public void testGetForValue() throws SQLException {

         System.out.println(customerDao.getCountWithName("a"));

     }

     @Test

     public void testAdd() throws SQLException {

         Customer customer = new Customer(null,"dsa", "dad", "sdas", "dsa");

         customerDao.save(customer);

     }

 //    按条件查询的测试方法

     @Test

     public void testGetListForLike() {

         CriteriaCustomer criteriaCustomer = new CriteriaCustomer("a","s",null, null);

         List<Customer> customerList = customerDao.getListOfLike(criteriaCustomer);

         System.out.println(customerList);

     }

     @Test

     public void testUpdate() {

         Customer customer = new Customer(null, "dsa", "dad", "sdas", "dsa");

         customerDao.update(customer, 19);

     }

     @Test

     public void testGetUserName() {

         Object cusName = customerDao.getCusName(6);

         System.out.println(cusName);

     }

 }

<%@ page import="com.java.homework.domain.Customer" %>

<%@ page import="java.util.List" %><%--

  Created by IntelliJ IDEA.

  User: yin‘zhao

  Date: 2017/11/13

  Time: 16:38

  To change this template use File | Settings | File Templates.

--%>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<html>

<head>

    <title>Customer</title>

</head>

</html>

<body>

<table cellspacing="10">

    <form action="list.do" method="post">

        <tr>

            <td>CusName:</td>

            <td><input type="text" name="cus_name"></td>

        </tr>

        <tr>

            <td>CusAddress:</td>

            <td><input type="text" name="cus_address"></td>

        </tr>

        <tr>

            <td>CusPhone:</td>

            <td><input type="text" name="cus_phone"></td>

        </tr>

        <tr>

            <td>CusThing:</td>

            <td><input type="text" name="cus_thing"></td>

        </tr>

        <tr>

            <td>

                <button type="submit">Submit</button>

            </td>

            <%--转到 add.jsp 进行添加用户--%>

            <td><a href="add.jsp">CreateNewCustomer</a></td>

        </tr>

    </form>

</table>

<table border="1" cellpadding="10" cellspacing="0">

    <%-- java 代码写在元素中，不应直接写在 body 中 --%>

    <%-- 获取所有的 customer 判断若不为空则将其打印在页面上 --%>

    <%

        List<Customer> customerList = (List<Customer>) request.getAttribute("customerList");

        if (customerList != null && customerList.size() > 0) {

    %>

    <tr>

        <th>CUSNAME</th>

        <th>CUSADDRESS</th>

        <th>CUSPHONE</th>

        <th>CUSTHING</th>

        <th>DELETE/UPDATE</th>

    </tr>

    <%

        for (int i = 0; i < customerList.size(); i++) {

    %>

    <tr>

        <td><%= customerList.get(i).getCustomerName()%>

        </td>

        <td><%= customerList.get(i).getCustomerAddress()%>

        </td>

        <td><%= customerList.get(i).getCustomerPhone()%>

        </td>

        <td><%= customerList.get(i).getCustomerThing()%>

        </td>

        <%--执行删除和更新操作--%>

        <td><a href="delete.do?id=<%= customerList.get(i).getId()%>" class="delete">DELETE</a>&nbsp;&nbsp;

            <a href="query.do?id=<%= customerList.get(i).getId()%>">UPDATE</a></td>

    </tr>

    <%

        }

    %>

    <%

        }

    %>

</table>

</body>

</html>

 <?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>AllServlet</servlet-name>

         <servlet-class>com.java.homework.controller.AllServlet</servlet-class>

     </servlet>

     <servlet-mapping>

         <servlet-name>AllServlet</servlet-name>

 <!-- 注意是 *.do -->

         <url-pattern>*.do</url-pattern>

     </servlet-mapping>

 </web-app>

 package com.java.homework.controller;

 import com.java.homework.criteria.CriteriaCustomer;

 import com.java.homework.dao.CustomerDao;

 import com.java.homework.daoImpl.CustomerDaoImpl;

 import com.java.homework.domain.Customer;

 import javax.servlet.ServletException;

 import javax.servlet.http.HttpServletRequest;

 import javax.servlet.http.HttpServletResponse;

 import java.io.IOException;

 import java.lang.reflect.InvocationTargetException;

 import java.lang.reflect.Method;

 import java.sql.SQLException;

 import java.util.List;

 /**

  * 使用反射实现多个请求使用同一个 Servlet，利用反射

  */

 public class AllServlet extends javax.servlet.http.HttpServlet {

     private CustomerDao customerDao = new CustomerDaoImpl();

     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws javax.servlet.ServletException, IOException {

 //        获取 servletPath，为 /xxx.do

         String servletPath = request.getServletPath();

 //        去除 servletPath 前面的 / 和后面的 .do

         String methodName = servletPath.substring(1).substring(0, servletPath.length() - 4);

         try {

 //            利用反射执行方法名为上述字符串的方法

             Method method = getClass().getDeclaredMethod(methodName, HttpServletRequest.class, HttpServletResponse.class);

             method.invoke(this, request, response);

         } catch (NoSuchMethodException e) {

             e.printStackTrace();

         } catch (IllegalAccessException e) {

             e.printStackTrace();

         } catch (InvocationTargetException e) {

             e.printStackTrace();

         }

     }

 //    若为 get 请求则执行 post 请求的方法

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

         doPost(request, response);

     }

 }

SELECT * FROM customer WHERE customer_name LIKE '%xx%' AND customer_address LIKE '%xx%' AND customer_phone LIKE '%123%' AND customer_thing LIKE '%%'

 package com.java.homework.criteria;

 /**

  * 封装查询条件的类

  */

 public class CriteriaCustomer {

     private String customerName;

     private String customerAddress;

     private String customerPhone;

     private String customerThing;

     public String getCustomerName() {

 //        如果其为空就将其置为 %%，否则将查询条件加在 %% 中间，拼出正确的 SQL 语句

         if (customerName == null) {

             customerName = "%%";

         } else {

             customerName = "%" + customerName + "%";

         }

         return customerName;

     }

     public String getCustomerAddress() {

         if (customerAddress == null) {

             customerAddress = "%%";

         } else {

             customerAddress = "%" + customerAddress + "%";

         }

         return customerAddress;

     }

     public String getCustomerPhone() {

         if (customerPhone == null) {

             customerPhone = "%%";

         } else {

             customerPhone = "%" + customerPhone + "%";

         }

         return customerPhone;

     }

     public String getCustomerThing() {

         if (customerThing == null) {

             customerThing = "%%";

         } else {

             customerThing = "%" + customerThing + "%";

         }

         return customerThing;

     }

     public CriteriaCustomer(String customerName, String customerAddress, String customerPhone, String customerThing) {

         this.customerName = customerName;

         this.customerAddress = customerAddress;

         this.customerPhone = customerPhone;

         this.customerThing = customerThing;

     }

 }

 //    显示数据表所有的信息

     protected void list(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

         List<Customer> customerList;

         String cusName = request.getParameter("cus_name");

         String cusAddress = request.getParameter("cus_address");

         String cusPhone = request.getParameter("cus_phone");

         String cusThing = request.getParameter("cus_thing");

 //         将查询条件封装为 CriteriaCustomer 对象

         CriteriaCustomer criteriaCustomer = new CriteriaCustomer(cusName, cusAddress, cusPhone, cusThing);

         if (cusName == null) {

 //             执行查询所有数据

             customerList = customerDao.getAll();

         } else {

 //             执行按条件查询

             customerList = customerDao.getListOfLike(criteriaCustomer);

         }

 //        将查询到的 List 对象添加到 request 域对象中，并转发到 index.jsp 中，在页面上显示数据库信息

         request.setAttribute("customerList", customerList);

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

     }

 protected void delete(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

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

         try {

             customerDao.delete(Integer.parseInt(id));

         } catch (SQLException e) {

             e.printStackTrace();

         }

 //        应该将重定向放于 try 块之后，那么如果出现异常也会转到 list.do，

         response.sendRedirect("list.do");

     }

 <%@ page import="com.java.homework.domain.Customer" %><%--

   Created by IntelliJ IDEA.

   User: yin‘zhao

   Date: 2017/11/13

   Time: 23:45

   To change this template use File | Settings | File Templates.

 --%>

 <%@ page contentType="text/html;charset=UTF-8" language="java" %>

 <html>

 <head>

     <title>UpdateCustomer</title>

 </head>

 <body>

 <table cellspacing="10">

     <%--保存错误消息，用户名重复时错误消息--%>

     <%

         String message = (String) request.getAttribute("message");

         Customer customer = (Customer) request.getAttribute("customer");

     %>

     <h3><%

         if (message != null) {

             out.print(message);

         }

     %></h3>

     <form action="update.do" method="post">

         <input type="hidden" name="id" value=<%=customer.getId()%>>

         <tr>

             <td>CusName:</td>

             <td><input type="text" name="cus_name" value=<%=customer.getCustomerName() %>></td>

         </tr>

         <tr>

             <td>CusAddress:</td>

             <td><input type="text" name="cus_address" value=<%=customer.getCustomerAddress() %>></td>

         </tr>

         <tr>

             <td>CusPhone:</td>

             <td><input type="text" name="cus_phone" value=<%=customer.getCustomerPhone()%>></td>

         </tr>

         <tr>

             <td>CusThing:</td>

             <td><input type="text" name="cus_thing" value=<%=customer.getCustomerThing()%>></td>

         </tr>

         <tr>

             <td>

                 <button type="submit">Update</button>

             </td>

         </tr>

     </form>

 </table>

 </body>

 </html>

 {

         Customer customer = getCustomer(request);

         Integer id = customer.getId();

         String cusName = customer.getCustomerName();

         String cusNameReal = (String) customerDao.getCusName(id);

         try {

             Long count = customerDao.getCountWithName(cusName);

             System.out.println(count);

 //            如果所传入的用户名的行数大于0，分为两种情况，没改存在一个，改了存在相同的

 //            由于或运算是计算了前面的若为假就不在执行后面的所以，当用户名相同时不判断后面的部分为正常操作，若不相等且有重复的则回馈错误信息

 //            也可以将旧的用户名存为一个隐藏表单，用上面同样的方法进行处理，与之相比少了对数据库的请求

 //            使用 equalsIgnoreCase 可以忽略大小写进行比较，那么在将当前值改为大写或者小写的时候就不会返回错误信息

             if (!(cusNameReal.equalsIgnoreCase(cusName)) && (count > 0)) {

                 String message = "用户名" + cusName + "已经被占用！";

 //                如果因为用户名重复那么就将传入 request 域中的 name 属性改为最原始的，其他属性为改好的

                 customer.setCustomerName(cusNameReal);

                 request.setAttribute("message", message);

                 request.setAttribute("customer", customer);

                 request.getRequestDispatcher("update.jsp").forward(request, response);

             } else {

                 customerDao.update(customer, id);

                 response.sendRedirect("list.do");

             }

         } catch (SQLException e) {

             e.printStackTrace();

         }

     }

 <%@ page import="com.java.homework.domain.Customer" %><%--

   Created by IntelliJ IDEA.

   User: yin‘zhao

   Date: 2017/11/13

   Time: 23:45

   To change this template use File | Settings | File Templates.

 --%>

 <%@ page contentType="text/html;charset=UTF-8" language="java" %>

 <html>

 <head>

     <title>CreateNewCustomer</title>

 </head>

 </html>

 <body>

 <br>

 <h3>

     <%--保存错误消息，当信息不完整和用户名重复时的错误消息--%>

     <%

     String message1 = (String) request.getAttribute("message1");

     String message2 = (String) request.getAttribute("message2");

     if (message1 != null) {

         out.print(message1);

     }

     if (message2 != null) {

         out.print(message2);

     }

 %></h3>

 <br>

 <table cellspacing="10">

     <form action="add.do" method="post">

         <tr>

             <td>CusName:</td>

             <td><input type="text" name="cus_name"

                        value=<%= request.getParameter("cus_name") == null ? "" : request.getParameter("cus_name")%>></td>

         </tr>

         <tr>

             <td>CusAddress:</td>

             <td><input type="text" name="cus_address"

                        value=<%= request.getParameter("cus_address") == null ? "" : request.getParameter("cus_address")%>></td>

         </tr>

         <tr>

             <td>CusPhone:</td>

             <td><input type="text" name="cus_phone"

                        value=<%= request.getParameter("cus_phone") == null ? "" : request.getParameter("cus_phone")%>></td>

         </tr>

         <tr>

             <td>CusThing:</td>

             <td><input type="text" name="cus_thing"

                        value=<%= request.getParameter("cus_thing") == null ? "" : request.getParameter("cus_thing")%>></td>

         </tr>

         <tr>

             <td>

                 <button type="submit">Submit</button>

             </td>

         </tr>

     </form>

 </table>

 </body>

 </html>

 {

         String cusName = request.getParameter("cus_name");

         String cusAddress = request.getParameter("cus_address");

         String cusPhone = request.getParameter("cus_phone");

         String cusThing = request.getParameter("cus_thing");

         Customer customer = new Customer(null, cusName, cusAddress, cusPhone, cusThing);

         Long count = null;

         try {

             count = customerDao.getCountWithName(cusName);

         } catch (SQLException e) {

             e.printStackTrace();

         }

         if (cusName.trim().equals("") || cusAddress.trim().equals("") || cusPhone.trim().equals("") || cusThing.trim().equals("")) {

             request.setAttribute("message1", "请输入完整的信息后在确认！");

             request.getRequestDispatcher("add.jsp").forward(request, response);

             return;

         }

         if (count > 0) {

             request.setAttribute("message2", "用户名" + cusName + "已经被占用");

             request.getRequestDispatcher("add.jsp").forward(request, response);

             return;

         }

         try {

             customerDao.save(customer);

 //            如果使用转发，那么新加的页面和list 页面将会冲突，导致list 页面将会执行模糊查询

 //            request.getRequestDispatcher("list.do").forward(request, response);

             response.sendRedirect("list.do");

         } catch (SQLException e) {

             e.printStackTrace();

         }

     }