JavaWeb同步学习笔记之三十二、JavaWeb_MVC案例之（模糊）查询

JavaWeb_MVC案例之（模糊）查询

MVC案例之（模糊）查询

MVC案例之（模糊）查询

-1. 查询操作：
　1）接上次笔记中CustomerServlet中query方法具体代码：

/**   
	 * @Title: query
	 * @Description: TODO
	 * @param request
	 * @param response 
	 * @return void
	 * @throws IOException 
	 * @throws ServletException 
	 */
	private void query(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//1.调用CustomerDAO的getAll()得到Customer的集合。
		List<Customer> customers = customerDAO.getAll();
		//2.把Customer的集合放入request中。
		request.setAttribute("customer", customers);
		//3.转发页面到index.jsp（不能使用重定向）。
		request.getRequestDispatcher("/index.jsp").forward(request, response);
		
	}

2）index.jsp：

<%@page import="com.xs.mvc_crud.domain.Customer"%>
<%@page import="java.util.List"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>

	<form action="query.do">
		<table border="1" cellpadding="10" cellspacing="0">
			<tr>
				<td>Name：</td>
				<td><input type="text" name="name" /></td>
			</tr>
			<tr>
				<td>Address：</td>
				<td><input type="text" name="address" /></td>
			</tr>
			<tr>
				<td>Phone：</td>
				<td><input type="text" name="phone" /></td>
			</tr>
			<tr>
				<td><input type="submit" value="Query" /></td>
				<td><a href="">Add New Customer</a></td>
			</tr>
		</table>
	</form>
	
	<br>
	<br>
	<hr>
	<br>
	<br>
	
	<%
		List<Customer> customers = (List<Customer>)request.getAttribute("customer");
		if(customers != null && customers.size() > 0) {
	%>
	<table border="1" cellpadding="10" cellspacing="0">
		<tr>
			<th>Id</th>
			<th>Name</th>
			<th>Address</th>
			<th>Phone</th>
			<th>Edit</th>
			<th>Delete</th>
		</tr>
		<%
			for(Customer customer: customers) {
		%>
		<tr>
			<td><%= customer.getId() %></td>
			<td><%= customer.getName() %></td>
			<td><%= customer.getAddress() %></td>
			<td><%= customer.getPhone() %></td>
			<td><a href="">Edit</a></td>
			<td><a href="">Delete</a></td>
		</tr>
		<%
			}
		%>
	</table>
	<%
		}
	%>

</body>
</html>

2.模糊查询
　1）根据传入的 name，address，phone 进行模糊查询。
　2）例子：name：a、address：b、phone：3，则 SQL 语句的样子为：

SELECT id, name, address, phone FROM customers WHERE name LIKE ‘%a%’ AND address LIKE ‘%b%’ AND phone LIKE ‘%3%’

.
　3）需要在 CustomerDAO 接口中定义一个 getForListWithCriteriaCustomer(CriteriaCustomer cc)。其中 CriteriaCustomer 用于封装查询条件：name，address，phone。因为查询条件很多时候和 domain 类并不相同，所以要做成一个单独的类。
　CriteriaCustomer 类：

/**  
 * All rights Reserved,Designed By XS
 * @Title: CriteriaCustomer.java
 * @Package com.xs.mvc_crud.dao
 * @Description: TODO
 * @author: XS
 * @date: 2019年3月9日 下午4:29:45
 * @version V1.0
 */
package com.xs.mvc_crud.dao;

/**   
 * @ClassName: CriteriaCustomer
 * @Description: TODO
 * @author: XS
 * @date: 2019年3月9日 下午4:29:45
 * @version V1.0
 */
public class CriteriaCustomer {
	
	private String name;
	
	private String address;
	
	private String phone;
	
	/**   
	 * @Title: CriteriaCustomer
	 * @Description: TODO
	 * @param name
	 * @param address
	 * @param phone
	 */
	public CriteriaCustomer(String name, String address, String phone) {
		super();
		this.name = name;
		this.address = address;
		this.phone = phone;
	}

	/**  
	 * @return the name
	 */
	public String getName() {
		if (name == null) 
			name = "%%";
		else 
			name = "%" + name + "%";
		return name;
	}

	/**  
	 * @param name: the name to set
	 */
	public void setName(String name) {
		this.name = name;
	}

	/**  
	 * @return the address
	 */
	public String getAddress() {
		if (address == null) 
			address = "%%";
		else 
			address = "%" + address + "%";
		return address;
	}

	/**  
	 * @param address: the address to set
	 */
	public void setAddress(String address) {
		this.address = address;
	}

	/**  
	 * @return the phone
	 */
	public String getPhone() {
		if (phone == null) 
			phone = "%%";
		else 
			phone = "%" + phone + "%";
		return phone;
	}

	/**  
	 * @param phone: the phone to set
	 */
	public void setPhone(String phone) {
		this.phone = phone;
	}
	
}
　4）拼 SQL：
```oracle
SELECT id, name, address, phone FROM customers WHERE name LIKE ? AND address LIKE ? AND phone LIKE ?

为了正确的填充占位符时，重写了 CriteriaCustomer 的 getter，具体的重写方式见CriteriaCustomer 实体类。
　5）修改 Servlet：获取请求参数；把请求参数封装为
CriteriaCustomer 对象，再调用 getForListWithCriteriaCustomer(CriteriaCustomer cc) 方法。
　CustomerDAO 类中加入：

/**   
	 * @Title: getForListWithCriteriaCustomer
	 * @Description: 封装了查询条件，返回满足查询条件的List。
	 * @param cc
	 * @return 
	 * @return List<Customer>
	 */
	public List<Customer> getForListWithCriteriaCustomer(CriteriaCustomer cc);

CustomerDAOJdbcImpl 中具体实现 getForListWithCriteriaCustomer() 方法：

/**   
	 * <p>Title: getForListWithCriteriaCustomer</p>
	 * <p>Description: </p>
	 * @see com.xs.mvc_crud.dao.CustomerDAO#getForListWithCriteriaCustomer(com.xs.mvc_crud.dao.CriteriaCustomer)
	 * @param cc
	 * @return
	 */
	@Override
	public List<Customer> getForListWithCriteriaCustomer(CriteriaCustomer cc){
		String sql = "SELECT id, name, address, phone FROM customers "
				+ "WHERE name LIKE ? AND address LIKE ? AND phone LIKE ?";
		return getForList(sql, cc.getName(), cc.getAddress(), cc.getPhone());
	}

修改CustomerServlet中的query方法：

/**   
	 * @Title: query
	 * @Description: TODO
	 * @param request
	 * @param response 
	 * @return void
	 * @throws IOException 
	 * @throws ServletException 
	 */
	private void query(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		String name = request.getParameter("name");
		String address = request.getParameter("address");
		String phone = request.getParameter("phone");
		CriteriaCustomer cc = new CriteriaCustomer(name, address, phone);
		//1.调用CustomerDAO的getForListWithCriteriaCustomer(cc)得到Customer的集合。
		List<Customer> customers = customerDAO.getForListWithCriteriaCustomer(cc);
		//2.把Customer的集合放入request中。
		request.setAttribute("customer", customers);
		//3.转发页面到index.jsp（不能使用重定向）。
		request.getRequestDispatcher("/index.jsp").forward(request, response);
		
	}