Java学习笔记——三层架构

Layer:

UI层:　　user interface 用户接口层

Biz层:　  service business login layer 业务逻辑层

DAO层:   Date Access Object 数据访问层

1.建立三层架构

UI层(对应包ui):这里就是一个简单的测试类

Biz层(对应包service):包括实体类的service层接口IGradeService和其实现类(impl包下)GradeServiceimpl

DAO层(对应包dao):BaseDAO工具类和实体类的dao层接口IGradeDAO和其实现类(impl包下)GradeDAOimpl

BaseDAO代码:

 package cn.happy.dao;

 import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;

 /**
  * database Data Access Object
  * 数据库访问工具类
  * Created by yanshaochen on 17-7-25.
  */
 public class BaseDAO {
     static final String URL="jdbc:mysql://127.0.0.1:3306/t14";
     static final String DRIVER="com.mysql.jdbc.Driver";
     static final String USR="root";
     static final String PASSWORD="root";
     private Connection con=null;
     private PreparedStatement ps=null;
     private ResultSet rs=null;
     //getConnection
     public Connection getConnection() throws Exception {
         Class.forName(DRIVER);
         if(con==null||con.isClosed()){
             con= DriverManager.getConnection(URL,USR,PASSWORD);
         }
         return con;
     }
     //close rs,ps,con
     public void closeResources() throws Exception {
         if(rs!=null)
             rs.close();
         if(ps!=null)
             ps.close();
         if(con!=null)
             con.close();
     }
     //executeUpdate
     public int executeUpdate(String sql,Object... objs) throws Exception {
         int count=;
         getConnection();
         ps=con.prepareStatement(sql);
         if(objs!=null){
             for (int i=;i<objs.length;i++){
                 ps.setObject(i+,objs[i]);
             }
         }         count=ps.executeUpdate();
         return count;
     }
     //executeQuery
     public ResultSet executeQuery(String sql,Object... objs) throws Exception {
         getConnection();
         ps=con.prepareStatement(sql);
         if(objs!=null){
             for (int i=;i<objs.length;i++){
                 ps.setObject(i+,objs[i]);
             }
         }         rs = ps.executeQuery();
         return rs;
     }
 }

实体类代码:

 package cn.happy.entity;

 /**
  * Created by yanshaochen on 17-7-25.
  */
 public class Grade {
     private String gradeName;

     public String getGrade() {
         return gradeName;
     }

     public void setGrade(String gradeName) {
         this.gradeName = gradeName;
     }
 }

Biz层接口代码:

 package cn.happy.service;

 import cn.happy.entity.Grade;

 /**
  * Created by yanshaochen on 17-7-25.
  */
 public interface IGradeService {
     boolean addGrade(Grade grade) throws Exception;
 }

实现类代码(与dao层联系):

 package cn.happy.service.impl;

 import cn.happy.dao.IGradeDAO;
 import cn.happy.dao.impl.GradeDAOImpl;
 import cn.happy.entity.Grade;
 import cn.happy.service.IGradeService;

 /**
  * Created by yanshaochen on 17-7-25.
  */
 public class GradeServiceImpl implements IGradeService {
     IGradeDAO dao=new GradeDAOImpl();
     @Override
     public boolean addGrade(Grade grade) throws Exception {
         return dao.addGrade(grade);
     }
 }

DAO层接口代码:

 package cn.happy.dao;

 import cn.happy.entity.Grade;

 /**
  * Created by yanshaochen on 17-7-25.
  */
 public interface IGradeDAO {
     boolean addGrade(Grade grade) throws Exception;
 }

实现类代码:

 package cn.happy.dao.impl;

 import cn.happy.dao.BaseDAO;
 import cn.happy.dao.IGradeDAO;
 import cn.happy.entity.Grade;

 /**
  * Created by yanshaochen on 17-7-25.
  */
 public class GradeDAOImpl extends BaseDAO implements IGradeDAO{
     @Override
     public boolean addGrade(Grade grade) throws Exception {
         boolean flag=false;
         String sql="insert into grade(gradeName)values(?);";
         int count = executeUpdate(sql,grade.getGrade());
         if(count>){
             flag=true;
         }
         return flag;
     }
 }

测试类代码:

 package cn.happy.ui;

 import cn.happy.entity.Grade;
 import cn.happy.service.IGradeService;
 import cn.happy.service.impl.GradeServiceImpl;

 /**
  * Created by yanshaochen on 17-7-25.
  */
 public class MyMain {
     public static void main(String[] args) throws Exception {
         Grade grade = new Grade();
         grade.setGrade("T21");
         IGradeService igs=new GradeServiceImpl();
         boolean isSuccess = igs.addGrade(grade);
         if(isSuccess){
             System.out.println("添加成功!");
         }else {
             System.out.println("添加失败!");
         }
     }
 }