SPRINGMYBATIS01 Unit05： 实战技巧 、 资费列表 、 拦截器

1. 系统分层 （扩展）

(1)为什么要分层?（了解)

为了系统好维护，系统的设计应该要做到“高内聚，低耦合”。“高内聚”：指的是类的职责要单一，这样，一个类就可以会拆分成多个类（比如AccountService拆分成了AccountService和AccountDAO）,这样，就形成了分层的概念。“低耦合”：指的是类与类之间不要直接依赖。（AccountService要调用AccountDAO，应该使用依赖注入）。

(2)如何分层?

表示层：数据展现和操作界面，以及请求分发。业务层：封装了业务逻辑。  持久层: 封装了数据访问逻辑。注：    表示层调用业务层，业务层调用持久层。    上一层通过接口来调用下一层提供的服务（这样，下一层的    实现发生了改变，不影响上一层）。

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案例：

/netctoss-spring/src/main/java/cn/tedu/netctoss/controller/LoginController.java

package cn.tedu.netctoss.controller;import javax.annotation.Resource;import javax.servlet.http.HttpServletRequest;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import cn.tedu.netctoss.entity.Admin;import cn.tedu.netctoss.service.ApplicationException;import cn.tedu.netctoss.service.LoginService;@Controllerpublic class LoginController {    @Resource(name="loginService")    private LoginService loginService;    @RequestMapping("/toLogin.do")    public String toLogin(){        System.out.println("toLogin()");        return "login";    }    @RequestMapping("/login.do")    public String login(            HttpServletRequest request){        System.out.println("login()");        //读取帐号，密码        String adminCode =                 request.getParameter(                        "adminCode");        System.out.println("adminCode:"                        + adminCode);        String pwd =                 request.getParameter("pwd");        //调用业务层提供的服务        try{            Admin admin =                 loginService.checkLogin(                        adminCode, pwd);        }catch(Exception e){            e.printStackTrace();            if(e instanceof ApplicationException){                //应用异常，明确提示用户                /*                 * getMessage方法继承自                 * RuntimeException，作用是                 * 获得异常的描述信息。                 */                request.setAttribute(                        "login_failed",                         e.getMessage());                return "login";            }            //系统异常,提示用户稍后重试            return "error";                 }        return "redirect:toIndex.do";    }    @RequestMapping("/toIndex.do")    public String toIndex(){        System.out.println("toIndex()");        return "index";    }}

/netctoss-spring/src/main/java/cn/tedu/netctoss/dao

AdminDAO.java

package cn.tedu.netctoss.dao;import cn.tedu.netctoss.entity.Admin;/** * 持久层接口 */public interface AdminDAO {    public Admin findByAdminCode(            String adminCode);}

AdminDAOJdbcImpl.java

package cn.tedu.netctoss.dao;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import javax.annotation.Resource;import javax.sql.DataSource;import org.springframework.stereotype.Repository;import cn.tedu.netctoss.entity.Admin;/** * 持久层实现 */@Repository("adminDAO")public class AdminDAOJdbcImpl implements AdminDAO{    @Resource(name="ds")    private DataSource ds;    public Admin findByAdminCode(            String adminCode) {        Admin admin = null;        Connection conn = null;        try {            conn = ds.getConnection();            String sql =                     "select * from admin_info_lhh "                    + "where admin_code=?";            PreparedStatement ps =                     conn.prepareStatement(                            sql);            ps.setString(1, adminCode);            ResultSet rs = ps.executeQuery();            if(rs.next()){                admin = new Admin();                admin.setAdminId(rs.getInt("admin_id"));                admin.setAdminCode(rs.getString("admin_code"));                admin.setPassword(rs.getString("password"));                admin.setName(rs.getString("name"));                admin.setTelephone(rs.getString("telephone"));                admin.setEmail(rs.getString("email"));                admin.setEnrolldate(rs.getTimestamp("enrolldate"));            }        } catch (SQLException e) {            //step1. 记日志（保留现场）            e.printStackTrace();            /*             * step2.看异常能否恢复,如果             * 不能够恢复(比如数据库服务             * 暂停，网络中断，这样的异常             * 一般我们称之为系统异常)，             * 则提示用户稍后重试。如果能够             * 恢复，则立即恢复。             *              */            throw new RuntimeException(e);        }finally{            if(conn != null){                try {                    conn.close();                } catch (SQLException e) {                    e.printStackTrace();                    throw new RuntimeException(e);                }            }        }        return admin;    }}

/netctoss-spring/src/main/java/cn/tedu/netctoss/entity/Admin.java

package cn.tedu.netctoss.entity;import java.io.Serializable;import java.sql.Timestamp;public class Admin implements Serializable{    private Integer adminId;    private String adminCode;    private String password;    private String name;    private String telephone;    private String email;    private Timestamp enrolldate;    @Override    public String toString() {        return "Admin [adminId=" + adminId + ", adminCode=" + adminCode + ", password=" + password + ", name=" + name                + ", telephone=" + telephone + ", email=" + email + ", enrolldate=" + enrolldate + "]";    }    public Integer getAdminId() {        return adminId;    }    public void setAdminId(Integer adminId) {        this.adminId = adminId;    }    public String getAdminCode() {        return adminCode;    }    public void setAdminCode(String adminCode) {        this.adminCode = adminCode;    }    public String getPassword() {        return password;    }    public void setPassword(String password) {        this.password = password;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getTelephone() {        return telephone;    }    public void setTelephone(String telephone) {        this.telephone = telephone;    }    public String getEmail() {        return email;    }    public void setEmail(String email) {        this.email = email;    }    public Timestamp getEnrolldate() {        return enrolldate;    }    public void setEnrolldate(Timestamp enrolldate) {        this.enrolldate = enrolldate;    }}

/netctoss-spring/src/main/java/cn/tedu/netctoss/service

ApplicationException.java

package cn.tedu.netctoss.service;/** * 应用异常类 * */public class ApplicationException     extends RuntimeException {    public ApplicationException() {    }    public ApplicationException(            String message) {        super(message);    }}

LoginService.java

package cn.tedu.netctoss.service;import cn.tedu.netctoss.entity.Admin;/** * 业务层接口 * */public interface LoginService {    public Admin checkLogin(String adminCode,            String pwd);}

LoginServiceImpl.java

package cn.tedu.netctoss.service;import javax.annotation.Resource;import org.springframework.stereotype.Service;import cn.tedu.netctoss.dao.AdminDAO;import cn.tedu.netctoss.entity.Admin;/** * 业务层实现 * */@Service("loginService")public class LoginServiceImpl implements LoginService{    @Resource(name="adminDAO")    private AdminDAO aDAO;    public Admin checkLogin(            String adminCode, String pwd) {        Admin admin =             aDAO.findByAdminCode(adminCode);        if(admin == null){            //帐号不存在,抛一个应用异常。            //注：应用异常，指的是因为用户            //不正确的操作引起的异常，比如            //帐号、密码填写错误。需要明确            //提示用户采取正确的操作。            throw new ApplicationException(                    "帐号错误");        }        if(!admin.getPassword().equals(pwd)){            //密码错误            throw new ApplicationException(                    "密码错误");        }        //登录成功        return admin;    }   }

/netctoss-spring/src/main/resources

db.properties

# db connection parametersdriver=oracle.jdbc.driver.OracleDriverurl=jdbc:oracle:thin:@localhost:1521:xeuser= pwd= # datasource parametersinitsize=1maxsize=2

spring-mvc.xml

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"    xmlns:jdbc="http://www.springframework.org/schema/jdbc" xmlns:jee="http://www.springframework.org/schema/jee"    xmlns:tx="http://www.springframework.org/schema/tx" xmlns:aop="http://www.springframework.org/schema/aop"    xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:util="http://www.springframework.org/schema/util"    xmlns:jpa="http://www.springframework.org/schema/data/jpa"    xsi:schemaLocation="        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd        http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd        http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd        http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.3.xsd        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd        http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd">    <!-- 配置组件扫描 -->    <context:component-scan base-package="cn.tedu.netctoss" />    <!-- 配置MVC注解扫描 -->    <mvc:annotation-driven />    <!-- 配置视图解析器 -->    <bean        class="org.springframework.web.servlet.view.InternalResourceViewResolver">        <property name="prefix" value="/WEB-INF/" />        <property name="suffix" value=".jsp" />    </bean>    <!-- 读取db.properties文件 -->    <util:properties id="db"     location="classpath:db.properties" />    <!-- 配置连接池 -->    <bean id="ds" class="org.apache.commons.dbcp.BasicDataSource"        destroy-method="close">        <property name="driverClassName" value="#{db.driver}" />        <property name="url" value="#{db.url}" />        <property name="username" value="#{db.user}" />        <property name="password" value="#{db.pwd}" />    </bean></beans>