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



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:

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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

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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:

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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:

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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:

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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:

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<%@ 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:

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<%@ 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:

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<%@ 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

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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");
    }
}
分类: java web