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）。

---

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;

@Controller
public 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 parameters
driver=oracle.jdbc.driver.OracleDriver
url=jdbc:oracle:thin:@localhost:1521:xe
user= 
pwd= 
# datasource parameters
initsize=1
maxsize=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>