[原创]java WEB学习笔记23：MVC案例完整实践(part 4)---模糊查询的设计与实现
2016-05-27 13:49
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-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------1.查询操作：
1）思路：
Servlet:在查询方法中，创建CustomerDAO 对象，调用getAll() 方法，获得List<Customer> 集合，利用保证为requset，转发，获取，遍历
//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("customers", customers);
//3. 转发页面到 index.jsp(不能使用重定向) request.getRequestDispatcher("/index.jsp").forward(request, response);
JSP
获取 request 中的 customers 属性
遍历显示
2）代码：
CustomerServlet2.java
Servlet中的 private void query(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{} 方法
package com.jason.mvcapp.servlet;
import java.io.IOException;
import java.lang.reflect.Method;
import java.util.List;
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 com.jason.mvcapp.dao.CustomerDAO;
import com.jason.mvcapp.dao.impl.CustomerDAOJdbcImpl;
import com.jsaon.mvcapp.domain.CriteriaCustomer;
import com.jsaon.mvcapp.domain.Customer;
/**
* Servlet implementation class CustomerServlet2
*/
@WebServlet("*.do")
public class CustomerServlet2 extends HttpServlet {
private static final long serialVersionUID = 1L;
//创建一个CustomerDAO对象，多态
private CustomerDAO customerDAO = new CustomerDAOJdbcImpl();
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
//1.获取servletPath：/add.do 或者 query.do
String serveltPath = request.getServletPath();
// System.out.println(serveltPath);
//2.去除/ 和 .do 得到对应的方法，如 add query
String methodName = serveltPath.substring(1);
methodName = methodName.substring(0, methodName.length() - 3);
// System.out.println(methodName);
try {
//3.利用反射获取methodName对应的方法
Method method = getClass().getDeclaredMethod(methodName,
HttpServletRequest.class, HttpServletResponse.class);
//4.利用反射调用方法
method.invoke(this, request, response);
} catch (Exception e) {
e.printStackTrace();
}
}
private void update(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
System.out.println("update");
}
private void editeCustomer(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
System.out.println("edit");
}
private void deleteCustomer(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
System.out.println("delete");
}
private void query(HttpServletRequest request, HttpServletResponse response)
78 throws ServletException, IOException {
79
80 // //1.调用CustomerDAO 的getAll()方法的到Customer 集合
81 // List<Customer> lists = customerDAO.getAll();
82 //2.把Customer 集合放入request
83 request.setAttribute("list", lists);
84 //3.转发页面到index.jsp
85 request.getRequestDispatcher("/index.jsp").forward(request, response);
86
87 }
private void addCustomer(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
System.out.println("add");
}
}index.jsp：获取list, 通过脚本遍历list集合，输出到表格中
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ page import="com.jsaon.mvcapp.domain.Customer" %>
<%@ page import="java.util.List" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>mve_index</title>
</head>
<body>
<form action="query.do" method="post">
<table>
<tr>
<td>CustomerName:</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>
<%
List<Customer> lists = (List<Customer>)request.getAttribute("list");
if(lists != null && lists.size() > 0 ){
%>
<hr>
<br><br>
<table border="1" cellpadding="10" cellspacing="0">
<tr>
<th>ID</th>
<th>CustomerName</th>
<th>Address</th>
<th>Phone</th>
<th>Update\Delete</th>
</tr>
<%
for(Customer customer : lists){
%>
<tr>
<td><%= customer.getId() %></td>
<td><%= customer.getName() %></td>
<td><%= customer.getAddress() %></td>
<td><%= customer.getPhone() %></td>
<td>
<a href="">Update</a>
<a href="">Delete</a>
</td>
</tr>
<%
}
%>
</table>
<%
}
%>
</body>
</html>2.模糊查询的设计和 实现
1）思路：
后端：
> 条件：根据传入的 name, address, phone 进行模糊查询.
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%
> 需要在 CustomerDAO 接口中定义一个 getForListWithCriteriaCustomer(CriteriaCustomer criteriaCustomer)。
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
package com.jsaon.mvcapp.domain;
/**
* @author: jason
* @time:2016年5月27日上午9:31:46
* @description:封装查询信息的类
*/
public class CriteriaCustomer {
private String name;
private String address;
private String phone;
public String getName() {
if(name == null){
name = "%%";
}else{
name = "%"+ name +"%";
}
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAddress() {
if(address == null){
address = "%%";
}else{
address = "%"+ address +"%";
}
return address;
}
public void setAddress(String address) {
this.address = address;
}
public String getPhone() {
if(phone == null){
phone = "%%";
}else{
phone = "%"+ phone +"%";
}
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public CriteriaCustomer(String name, String address, String phone) {
super();
this.name = name;
this.address = address;
this.phone = phone;
}
public CriteriaCustomer() {
super();
}
}>在CustomerDAOJdbcImpl 中重写CustomerDAO 中的getForListWithCriteriaCustomer(CriteriaCustomer criteriaCustomer)
@Override
public List<Customer> getForListWithCriteriaCustomer(
CriteriaCustomer criteriaCustomer) {
//sql语句
String sql = "SELECT id,name,address,phone FROM customers WHERE name LIKE ? AND address LIKE ? AND phone LIKE ?";
//调用DAO<T> 中的方法getForList(),并且为占位符设置参数
return getForList(sql, criteriaCustomer.getName(),criteriaCustomer.getAddress(),criteriaCustomer.getPhone());
}> 拼 SQL： "SELECT id, name, address, phone FROM customers WHERE " + "name LIKE ? AND address LIKE ? ANDphone LIKE ?";
> 为了正确的填充占位符时，重写了 CriteriaCustomer 的 getter方法
//获取Name
public String getName() {
if(name == null){
name = "%%";
}else{
name = "%"+ name +"%";
}
return name;
}
//获取Address
public String getAddress() {
if(address == null){
address = "%%";
}else{
address = "%"+ address +"%";
}
return address;
}
//获取Phone
public String getPhone() {
if(phone == null){
phone = "%%";
}else{
phone = "%"+ phone +"%";
}
return phone;
}> 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
private void query(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//设置编码格式
request.setCharacterEncoding("UTF-8");
//获取相应的参数
String name = request.getParameter("name");
String address = request.getParameter("address");
String phone = request.getParameter("phone");
//封装请求参数
CriteriaCustomer criteriaCustomer = new CriteriaCustomer(name,address,phone);
//1.调用CustomerDAO 的getForListWithCriteriaCustomer(criteriaCustomer)方法的到Customer 集合
List<Customer> lists = customerDAO.getForListWithCriteriaCustomer(criteriaCustomer);
//2.把Customer 集合放入request
request.setAttribute("list", lists);
//3.转发页面到index.jsp
request.getRequestDispatcher("/index.jsp").forward(request, response);
}前台：同上述的JSP
获取 request 中的 customers 属性
遍历显示
2）代码：
CriteriaCustomer.java
package com.jsaon.mvcapp.domain;
/**
* @author: jason
* @time:2016年5月27日上午9:31:46
* @description:封装查询信息的类
*/
public class CriteriaCustomer {
private String name;
private String address;
private String phone;
public String getName() {
if(name == null){
name = "%%";
}else{
name = "%"+ name +"%";
}
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAddress() {
if(address == null){
address = "%%";
}else{
address = "%"+ address +"%";
}
return address;
}
public void setAddress(String address) {
this.address = address;
}
public String getPhone() {
if(phone == null){
phone = "%%";
}else{
phone = "%"+ phone +"%";
}
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public CriteriaCustomer(String name, String address, String phone) {
super();
this.name = name;
this.address = address;
this.phone = phone;
}
public CriteriaCustomer() {
super();
}
}CustomerServlet2.java
package com.jason.mvcapp.servlet;
import java.io.IOException;
import java.lang.reflect.Method;
import java.util.List;
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 com.jason.mvcapp.dao.CustomerDAO;
import com.jason.mvcapp.dao.impl.CustomerDAOJdbcImpl;
import com.jsaon.mvcapp.domain.CriteriaCustomer;
import com.jsaon.mvcapp.domain.Customer;
/**
* Servlet implementation class CustomerServlet2
*/
@WebServlet("*.do")
public class CustomerServlet2 extends HttpServlet {
private static final long serialVersionUID = 1L;
//创建一个CustomerDAO对象，多态
private CustomerDAO customerDAO = new CustomerDAOJdbcImpl();
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
//1.获取servletPath：/add.do 或者 query.do
String serveltPath = request.getServletPath();
// System.out.println(serveltPath);
//2.去除/ 和 .do 得到对应的方法，如 add query
String methodName = serveltPath.substring(1);
methodName = methodName.substring(0, methodName.length() - 3);
// System.out.println(methodName);
try {
//3.利用反射获取methodName对应的方法
Method method = getClass().getDeclaredMethod(methodName,
HttpServletRequest.class, HttpServletResponse.class);
//4.利用反射调用方法
method.invoke(this, request, response);
} catch (Exception e) {
e.printStackTrace();
}
}
private void update(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
System.out.println("update");
}
private void editeCustomer(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
System.out.println("edit");
}
private void deleteCustomer(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
System.out.println("delete");
}
private void query(HttpServletRequest request, HttpServletResponse response)
78 throws ServletException, IOException {
79 request.setCharacterEncoding("UTF-8");
80 String name = request.getParameter("name");
81 String address = request.getParameter("address");
82 String phone = request.getParameter("phone");
83
84
85
86 CriteriaCustomer criteriaCustomer = new CriteriaCustomer(name,address,phone);
87 List<Customer> lists = customerDAO.getForListWithCriteriaCustomer(criteriaCustomer);
88
89
90 // //1.调用CustomerDAO 的getAll()方法的到Customer 集合
91 // List<Customer> lists = customerDAO.getAll();
92 //2.把Customer 集合放入request
93 request.setAttribute("list", lists);
94 //3.转发页面到index.jsp
95 request.getRequestDispatcher("/index.jsp").forward(request, response);
96
97 }
private void addCustomer(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
System.out.println("add");
}
}CustomerDAOJdbcImpl.java
package com.jason.mvcapp.dao.impl;
import java.util.List;
import com.jason.mvcapp.dao.CustomerDAO;
import com.jason.mvcapp.dao.DAO;
import com.jsaon.mvcapp.domain.CriteriaCustomer;
import com.jsaon.mvcapp.domain.Customer;
/**
* @author: jason
* @time:2016年5月25日下午3:45:06
* @description:对CustomerDAO 的实现
*/
public class CustomerDAOJdbcImpl extends DAO<Customer> implements CustomerDAO {
@Override
public List<Customer> getAll() {
String sql = "SELECT * FROM customers";
return getForList(sql);
}
@Override
public void save(Customer customer) {
String sql = "INSERT INTO customers(name, address, phone) VALUES(?,?,? )";
update(sql,customer.getName(),customer.getAddress(),customer.getPhone());
}
@Override
public Customer get(Integer id) {
String sql = "SELECT id, name, address, phone FROM customers WHERE id = ?";
return get(sql,id);
}
@Override
public void delete(Integer id) {
String sql = "DELETE FROM customers WHERE id = ?";
update(sql, id);
}
@Override
public long getCountWithName(String name) {
String sql = "SELECT count(id) FROM customers WHERE name = ?";
return getForValue(sql, name);
}
@Override
50 public List<Customer> getForListWithCriteriaCustomer(
51 CriteriaCustomer criteriaCustomer) {
52 //sql语句
53 String sql = "SELECT id,name,address,phone FROM customers WHERE name LIKE ? AND address LIKE ? AND phone LIKE ?";
54 //调用DAO<T> 中的方法getForList(),并且为占位符设置参数
55 return getForList(sql, criteriaCustomer.getName(),criteriaCustomer.getAddress(),criteriaCustomer.getPhone());
56 }
}CustomerDAO.java
package com.jason.mvcapp.dao;
import java.util.List;
import com.jsaon.mvcapp.domain.CriteriaCustomer;
import com.jsaon.mvcapp.domain.Customer;
/**
* @author: jason
* @time:2016年5月25日下午3:28:00
* @description:
*/
public interface CustomerDAO {
//带参数的模糊查询
18 public List<Customer> getForListWithCriteriaCustomer(CriteriaCustomer criteriaCustomer);
//查询所有
public List<Customer> getAll();
//保存操作
public void save(Customer coustomer);
//更新前，先查询
public Customer get(Integer id);
//删除用户
public void delete(Integer id);
//查看与参数相同的名字有多少个记录数
public long getCountWithName(String name);
}index.jsp 同上面的一样
总结：
1）理解代码的层次
2）在从前台获取参数的时候，一定要设置 request.setCharacterEncoding("UTF-8"); 。我在跑测试的时候，由于没有设置编码格式，在debug 运行的时候，获取到的 name，address，phone都是乱码。一定注意
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