java软件设计的三层结构

接口：

package dao;

public interface Dao {
    String getData();
}

package biz;

import dao.Dao;

public interface Biz {
    void setDao(Dao dao);
    String dealData();
}

package view;

import biz.Biz;

public interface View {
    void setBiz(Biz biz);
    void showData();
}

实现类：

package dao;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

public class FileDaoImpl implements Dao {

    @Override
    public String getData() {
        String data= null;
        BufferedReader br= null;
        try {
            br= new BufferedReader(new FileReader("test.txt"));
            data= br.readLine();
        }  catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally {
            if (br!=null) {
                try {
                    br.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }
        return data;
    }

}

package biz;

import dao.Dao;

public class UpperCaseBizImpl implements Biz {
    private Dao dao;
    @Override
    public void setDao(Dao dao) {
        this.dao= dao;
    }

    @Override
    public String dealData() {
        String data= dao.getData();
        if (data != null) {
            data.toUpperCase();
        }
        return data;
    }

}

package view;

import biz.Biz;

public class TextViewImpl implements View {
    private Biz biz;
    @Override
    public void setBiz(Biz biz) {
        this.biz= biz;
    }

    @Override
    public void showData() {
        String data= biz.dealData();
        System.out.println(data);
    }

}

Object Factory:

package factory;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

import biz.Biz;

import view.View;

import dao.Dao;

public class SimpleFactory {
    private Properties properties;
    public SimpleFactory() {
        properties= new Properties();
        InputStream is= null;
        try {
            is= new FileInputStream("conf.properties");
            properties.load(is);
        }  catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally {
            if (is!=null) {
                try {
                    is.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }
    }
    
    public Dao createDao(){
        String className = properties.getProperty("dao");
        return (Dao)createObject(className);
    }
    public Biz createBiz(){
        String className= properties.getProperty("biz");
        return (Biz) createObject(className);
    }
    public View createView(){
        String className= properties.getProperty("view");
        return (View) createObject(className);
    }
    private Object createObject(String name){
        Object result= null;
        try {
            Class clazz = Class.forName(name);
            result = clazz.newInstance();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (InstantiationException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return result;
    }
}

配置文件：conf.properties

view=view.TextViewImpl
biz=Biz.UpperCaseBizImpl
dao=Dao.FileDaoImpl

文本文件：test.txt

HELLO WORLD

测试类：

package test;

import view.View;
import biz.Biz;
import dao.Dao;
import factory.SimpleFactory;

public class TestMain {

    /**
     * @param args
     */
    public static void main(String[] args) {
        SimpleFactory simpleFactory= new SimpleFactory();
        Dao dao= simpleFactory.createDao();
        Biz biz= simpleFactory.createBiz();
        biz.setDao(dao);
        View view = simpleFactory.createView();
        view.setBiz(biz);
        view.showData();
    }

}

output:

HELLO WORLD