java web基础之mvc模式设计（一）--使用httpservlet实现mvc分层设计，DAO层使用的是dbutils实现与数据库的链接

一：1.最终的实现效果图：

2.案例的目录结构：

3.案例中使用到的jar包：

二：案例的链接数据库的层次结构关系：数据库是：mysql ，数据库名字：dsm,表格名字：customers

数据库表格的样子是：

数据库实现中用到的各个类的层次关系：

上述java类中的源代码：

Dao.java:

package com.guodiantong.mvc.dao;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.sql.Connection;
import java.util.List;

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 com.guodiantong.mvc.db.JdbcUtils;

public class Dao<T> {
   
	private QueryRunner queryRunner=new QueryRunner();
	private Class<T> clazz;
	
	public Dao(){
		Type superClass=getClass().getGenericSuperclass();
		if(superClass instanceof ParameterizedType){
			ParameterizedType parameterizedType= (ParameterizedType) superClass;
			
			Type[] typeArgs=parameterizedType.getActualTypeArguments();
			if(typeArgs!=null&&typeArgs.length>0){
			   if(typeArgs[0] instanceof Class){
				   clazz=(Class<T>) typeArgs[0];
			   }	
			}
		}
	}
	/*
	 * 这个方法是只获取，表格中的某一行属性中的某一个属性值，就是返回某一个字段的值，例如返回某一条记录的customerName，或者返回数据表中有多少条记录等。
	 */
	public <E> E getForValue(String sql,Object ... args){
		Connection connection=null;
		try {connection=JdbcUtils.getConnection();
			return (E) queryRunner.query(connection, sql, new ScalarHandler(), args);
		} catch (Exception e) {
            e.printStackTrace();
		}finally{
			JdbcUtils.releaseConnection(connection);
		}
		return null;
	}
	
	/*
	 * 该方法是返回一组数据对象实体类，返回T所对应的List，其实质就是查询
	 */
	public List<T> getForList(String sql,Object ... agrs ){
		Connection connection=null;
		try {connection=JdbcUtils.getConnection();
			return queryRunner.query(connection, sql, new BeanListHandler<T>(clazz), agrs);
		} catch (Exception e) {
           e.printStackTrace();
		}finally{
			JdbcUtils.releaseConnection(connection);
		}
		return null;
	}
	/*
	 * 执行查询的语句，结果是返回数据表中的一个对象（一条记录）其实质就是查询！
	 */
	  public T get(String sql,Object ... agrs){
		 
		  Connection connection=null;
		  try {connection=JdbcUtils.getConnection();
			return queryRunner.query(connection, sql, new BeanHandler<T>(clazz), agrs);
		} catch (Exception e) {
               e.printStackTrace();
		}finally{
			JdbcUtils.releaseConnection(connection);
		}
		 return null;
	  }
	/*
	 * 该方法封装了INSERT、UPDATE、DELETE操作
	 * sql是sql语句
	 * args是占位符
	 */
	public void update(String sql,Object ... args){
		Connection connection=null;
		try {connection=JdbcUtils.getConnection();
		queryRunner.update(connection, sql, args);
			
		} catch (Exception e) {
           e.printStackTrace();
		}finally{
			JdbcUtils.releaseConnection(connection);
		}
	}
}

　JdbcUtils.java　

package com.guodiantong.mvc.db;

import java.sql.Connection;
import java.sql.SQLException;

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;



public class JdbcUtils {
/*
 *释放数据库的连接
 * 
 */
	public static void releaseConnection(Connection connection){
	
		try {
			if(connection !=null){
				connection.close();
			}
		} catch (Exception e) {
          e.printStackTrace();
		}
	}
	
	private static DataSource dataSource=null;
	static {
		/*
		 * 数据源只能被创建一次
		 */
		dataSource=new ComboPooledDataSource("mvcapp");
	}
	
	public static Connection getConnection() throws SQLException{
		//dataSource=new ComboPooledDataSource("mvcapp");若要是放在这里就说明，获得一次就创建一下，比较耗费内存
		return dataSource.getConnection();
	}
}

说明一下这里的　“mvcapp”参数，这个参数是在c3p0-config.xml文件中的一项配置（<named-config name="mvcapp">）

　Customer.java:

package com.guodiantong.mvc.domain;

public class Customer {
  private Integer id;
  private String name;
  private String address;
  private String phone;
public Integer getId() {
	return id;
}
public void setId(Integer id) {
	this.id = id;
}
public String getName() {
	return name;
}
public void setName(String name) {
	this.name = name;
}
public String getAddress() {
	return address;
}
public void setAddress(String address) {
	this.address = address;
}
public String getPhone() {
	return phone;
}
public void setPhone(String phone) {
	this.phone = phone;
}
public Customer(Integer id, String name, String address, String phone) {
	super();
	this.id = id;
	this.name = name;
	this.address = address;
	this.phone = phone;
}
public Customer() {
	super();
}
@Override
public String toString() {
	return "Customer [id=" + id + ", name=" + name + ", address=" + address
			+ ", phone=" + phone + "]";
}
  
}

　　CustomerDao.java:

package com.guodiantong.mvc.dao;

import java.util.List;

import com.guodiantong.mvc.domain.CriteriaCustomer;
import com.guodiantong.mvc.domain.Customer;

public interface CustomerDao {
    
	public List<Customer> getForListWithCriteriaCustomer(CriteriaCustomer cc);
	public List<Customer> getAll();
	
	public void save(Customer customer);
	
	public Customer get(Integer id);
	
	public void delete(Integer id);
	
	/*
	 * 根据查询的名字，返回使用该名字的数据条数
	 */
	public long getCountWithName(String name);
	
	public void update(Customer customer);
}

　　CustomerDaoJdbcImpl.java:

package com.guodiantong.mvc.impl;

import java.util.List;

import com.guodiantong.mvc.dao.CustomerDao;
import com.guodiantong.mvc.dao.Dao;
import com.guodiantong.mvc.domain.CriteriaCustomer;
import com.guodiantong.mvc.domain.Customer;

public class CustomerDaoJdbcImpl extends Dao<Customer>implements CustomerDao {
	
	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());
	}
	@Override
	public List<Customer> getAll() {
		String sql="SELECT id,name,address,phone 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
	public void update(Customer customer) {
		String sql="UPDATE customers SET name=?, address=?, phone=? WHERE id=?";
		update(sql, customer.getName(),customer.getAddress(),customer.getPhone(),customer.getId());
		
	}

	
	
}

　　说明：Dao.java 和JdbcUtils.java具有可移植性，在哪个工程项目中都能用，CustomerDao.java和CustomerDaoImpl.java 是根据具体的项目抽象出可能用到的方法，然后让底层Dao.java最基础的增删改查等功能来拼凑出项目中页面中抽象的方法

三：项目中jsp文件的编写（jsp实质上就是一个servlet）

案例中用到最多的无非是HttpServletRequest  request,HttpServletResponse response这两个参数结合页面中的表单form以及转发方式等在页面和后台servlet之间传递数据

开始页面的jsp：index.jsp:

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
    <%@ page import="java.util.List" %>
  <%@ page import="com.guodiantong.mvc.domain.Customer" %>
<!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>Insert title here</title>
<script type="text/javascript" src="script/jquery-1.7.2.js"></script>
<script type="text/javascript">
  $(function(){
	$(".delete").click(function(){
		var content=$(this).parent().parent().find("td:eq(1)").text();
		var flag =confirm("确定要删除" + content + "的信息吗？");
		return flag;
	});  
  });
</script>
</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="addCustomer.jsp">Add Customer123</a></td>   
   </tr>
</table>
</form>
<hr>
<br>

<% 
   List<Customer> customer=(List<Customer>)request.getAttribute("customers");
   if(customer!=null && customer.size()>0){
	%>
	  <table border="1" cellspacing="0" cellpadding="10">
  <tr>
  <th>id</th>
  <th>name</th>
  <th>address</th>
  <th>phone</th>
  <th>delete</th>
  <th>edit</th>
  </tr>
  

  <%
     for(Customer cust:customer)
     {
  %>  
      <tr>
    	<td><%=cust.getId() %></td>
    	<td><%=cust.getName() %></td>
    	<td><%=cust.getAddress() %></td>
    	<td><%=cust.getPhone() %></td>
    	<td><a class="delete" href="delete.do?id=<%=cust.getId()%>">delete</a></td>
    	<td><a class="edit"   href="edit.do?id=<%=cust.getId() %>">edit</a></td> 
      </tr>
  
  <% 	 
     }
  %>
     
<%	   
   }
%>

  
  
  </table>
</body>
</html>

　　新增页面的jsp：addCustomer.jsp:

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!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>Insert title here</title>
</head>
<body>
 



    <% Object msg=request.getAttribute("message");
    if(msg!=null){
    %>
    <%=request.getAttribute("message")%>
    <%	
    }
    
    %>
<form action="addCustomer.do" method="post">
 <table>
 <tr>
     <td>customerName:<input type="text" name="name"
      value="<%=request.getAttribute("name")==null? "":request.getAttribute("name") %>"></td>
 </tr>
 <tr>
     <td>address:<input type="text" name="address"
      value="<%=request.getAttribute("address")==null? "":request.getAttribute("address") %>"></td>
 </tr>
 <tr>
     <td>phone:<input type="text" name="phone"
     value="<%=request.getAttribute("phone")==null? "":request.getAttribute("phone") %>"></td>
 </tr>
 <tr>
     <td><input  type="submit" value="submit"></td>
     
 </tr>
 </table>
</form>
</body>
</html>

　　编辑页面的jsp：edit.jsp:

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
 <%@ page import="com.guodiantong.mvc.domain.Customer" %>
<!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=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
	<% 
		Object msg = request.getAttribute("message");
		if(msg != null){
	%>
			<br>
			<font color="red"><%= msg %></font>
			<br>
			<br>
	<%
		}
		
		String id = null;
		String oldName = null;
		String name = null;
		String address = null;
		String phone = null;
		
		Customer customer = (Customer)request.getAttribute("customer");
		if(customer != null){
			id = customer.getId() + "";
			oldName = customer.getName();
			name = customer.getName();
			address = customer.getAddress();
			phone = customer.getPhone();
		}else{
			id = request.getParameter("id");
			oldName = request.getParameter("oldName");
			name = request.getParameter("oldName");
			
			address = request.getParameter("address");
			phone = request.getParameter("phone");
		}
	%>
	
	<form action="update.do" method="post">
	
		<input type="hidden" name="id" value="<%= id %>"/>
		<input type="hidden" name="oldName" value="<%= oldName %>"/>
	
		<table>
			<tr>
				<td>CustomerName:</td>
				<td><input type="text" name="name" 
					value="<%= name %>"/></td>
			</tr>
			<tr>
				<td>Address:</td>
				<td><input type="text" name="address" 
					value="<%= address %>"/></td>
			</tr>
			<tr>
				<td>Phone:</td>
				<td><input type="text" name="phone" 
					value="<%= phone %>"/></td>
			</tr>
			<tr>
				<td colspan="2"><input type="submit" value="Submit"/></td>
			</tr>
		</table>
	</form>
</body>
</html>

　　四.后台中的控制类Servlet   CustomerServlet.java

package com.guodiantong.mvc.servlet;

import java.io.IOException;
import java.lang.reflect.Method;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.guodiantong.mvc.dao.CustomerDao;
import com.guodiantong.mvc.domain.CriteriaCustomer;
import com.guodiantong.mvc.domain.Customer;
import com.guodiantong.mvc.impl.CustomerDaoJdbcImpl;

public class CustomerServlet extends HttpServlet {
    CustomerDao customerDao=new CustomerDaoJdbcImpl();
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
       doPost(req, resp);

	}

	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
     String servletPath=req.getServletPath();
     System.out.println(servletPath);
     String methodName=servletPath.substring(1);
            methodName=methodName.substring(0, methodName.length()-3);
            /*
             * 利用反射获取methodName对应的方法
             */
     try {
		  Method method=getClass().getDeclaredMethod(methodName, HttpServletRequest.class,
				  HttpServletResponse.class);
    	 //利用反射调用对应的方法
		  method.invoke(this, req,resp);
	} catch (Exception e) {
		e.printStackTrace();
		resp.sendRedirect("error.jsp");
	}
     
	}
	
	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 criteriaCustomer=new CriteriaCustomer(name, address, phone);
		
		List<Customer> customers=customerDao.getForListWithCriteriaCustomer(criteriaCustomer);
		System.out.println(customers);
		request.setAttribute("customers", customers);
		request.getRequestDispatcher("/index.jsp").forward(request, response);
	}
    private void delete(HttpServletRequest request,HttpServletResponse response) throws IOException{
    	String idstr=request.getParameter("id");
    	int id=0;
    	
    	try {
			id=Integer.parseInt(idstr);
			System.out.println(id);
			customerDao.delete(id);
		} catch (Exception e) {
			
		}
    	response.sendRedirect("query.do");
    }
    
    private void addCustomer(HttpServletRequest resquest,HttpServletResponse response) throws IOException, ServletException{
    	String name=resquest.getParameter("name");
    	String address=resquest.getParameter("address");
    	String phone=resquest.getParameter("phone");
    	//String message="用户" + name + "已经注册过了";
    	long count=customerDao.getCountWithName(name);
    	if(count>0){
    		//resquest.setAttribute("count", count);
    		resquest.setAttribute("message","用户" + name + "已经注册过了");
    		resquest.setAttribute("address", address);
    		resquest.setAttribute("phone", phone);
    		resquest.getRequestDispatcher("/addCustomer.jsp").forward(resquest, response);
    	}
    	else{
    	Customer customer=new Customer(null, name, address, phone);
    	
    	
    	customerDao.save(customer);
    	response.sendRedirect("query.do");}
    }
    private void edit(HttpServletRequest request,HttpServletResponse response){
    	String idstr=request.getParameter("id");
    	int id=0;
    	
    	try {
			id=Integer.parseInt(idstr);
			Customer cus=customerDao.get(id);
//			String name=cus.getName();
//			String address=cus.getAddress();
//			String phone=cus.getPhone();
//			request.setAttribute("name", name);
//			request.setAttribute("address", address); 
			request.setAttribute("customer", cus);
			request.getRequestDispatcher("/edit.jsp").forward(request, response);
		} catch (Exception e) {
			// TODO: handle exception
		}
    } 
    
    private void update(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException{
    
    	//1. 获取表单参数: id, name, address, phone, oldName
		String id = request.getParameter("id");
		String name = request.getParameter("name");
		String phone = request.getParameter("phone");
		String address = request.getParameter("address");
		String oldName = request.getParameter("oldName");
		
		//2. 检验 name 是否已经被占用:
		
		//2.1 比较 name 和 oldName 是否相同, 若相同说明 name 可用. 
		//2.1 若不相同, 则调用 CustomerDAO 的 getCountWithName(String name) 获取 name 在数据库中是否存在
		if(!oldName.equalsIgnoreCase(name)){
			long count = customerDao.getCountWithName(name);
			//2.2 若返回值大于 0, 则响应 updatecustomer.jsp 页面: 通过转发的方式来响应 newcustomer.jsp
			if(count > 0){
				//2.2.1 在 updatecustomer.jsp 页面显示一个错误消息: 用户名 name 已经被占用, 请重新选择!
				//在 request 中放入一个属性 message: 用户名 name 已经被占用, 请重新选择!, 
				//在页面上通过 request.getAttribute("message") 的方式来显示
				request.setAttribute("message", "用户名" + name + "已经被占用, 请重新选择!");
				
				//2.2.2 newcustomer.jsp 的表单值可以回显. 
				//address, phone 显示提交表单的新的值, 而 name 显示 oldName, 而不是新提交的 name
				
				//2.2.3 结束方法: return 
				request.getRequestDispatcher("/updatecustomer.jsp").forward(request, response);
				return;
			}
		}
		
		//3. 若验证通过, 则把表单参数封装为一个 Customer 对象 customer
		Customer customer = new Customer(null, name, address, phone);
		customer.setId(Integer.parseInt(id)); 
		
		//4. 调用 CustomerDAO 的  update(Customer customer) 执行更新操作
		customerDao.update(customer);
		
		//5. 重定向到 query.do
		response.sendRedirect("query.do");
    }
}