设计模式课程 设计模式精讲 3-11 合成复用原则coding

1　　　　课堂概念

2　　　　代码演练

2.1　　反例

2.2　　正例

1　　　　课堂概念

2　　　　代码演练

2.1　　反例

 类关系：

测试类：

package com.geely.design.principle.compositionaggregation;

public class TestBizDao {
    public static void main(String [] args){
        BizDaoNegative bizDaoNegative = new BizDaoNegative();
        bizDaoNegative.getDBConnection();
    }

//    public static void main(String [] args){
//        BizDao bizDao = new BizDao();
////        DBConnection dbConnection = new MySqlConnection();
////        bizDao.setDbConnection(dbConnection);
//        DBConnection dbConnection = new OracleConnection();
//        bizDao.setDbConnection(dbConnection);
//        bizDao.handleBiz();
//    }
}

dao类：

package com.geely.design.principle.compositionaggregation;

public class BizDaoNegative extends DBConnectionNegative{

    @Override
    public void getDBConnection() {
        super.getDBConnection();
    }
}

获取连接类：

package com.geely.design.principle.compositionaggregation;

public class DBConnectionNegative {
    public void getDBConnection(){
        System.out.println("打开MySql连接");
    }
}

打印结果：

"C:\Program Files\Java\jdk1.6.0_43\bin\java.exe" "-javaagent:D:\java\devolopKit\idea\anZh\IntelliJ IDEA Community Edition 2018.1.4\lib\idea_rt.jar=9805:D:\java\devolopKit\idea\anZh\IntelliJ IDEA Community Edition 2018.1.4\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.6.0_43\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\jce.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\resources.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\rt.jar;F:\xiangmu3\Xin\Idea\out\production\design_pattern" com.geely.design.principle.compositionaggregation.TestBizDao
打开MySql连接

Process finished with exit code 0

2.2　　正例

类图：

测试类：

package com.geely.design.principle.compositionaggregation;

public class TestBizDao {
//    public static void main(String [] args){
//        BizDaoNegative bizDaoNegative = new BizDaoNegative();
//        bizDaoNegative.getDBConnection();
//    }

    public static void main(String [] args){
        BizDao bizDao = new BizDao();
        DBConnection dbConnection = new MySqlConnection();
//        bizDao.setDbConnection(dbConnection);
//        DBConnection dbConnection = new OracleConnection();
        bizDao.setDbConnection(dbConnection);
        bizDao.handleBiz();
    }
}

dao类：

package com.geely.design.principle.compositionaggregation;

public class BizDao {
    private DBConnection dbConnection;

    public void setDbConnection(DBConnection dbConnection) {
        this.dbConnection = dbConnection;
    }

    public void handleBiz(){
       dbConnection.getConnection();
    }
}

获取连接抽象类：

package com.geely.design.principle.compositionaggregation;

public abstract class DBConnection {
    public abstract void getConnection();
}

获取Mysql连接类：

package com.geely.design.principle.compositionaggregation;

public class MySqlConnection extends DBConnection{
    @Override
    public void getConnection() {
        System.out.println("打开MySql连接");
    }
}

获取Oracle连接类：

package com.geely.design.principle.compositionaggregation;

public class OracleConnection extends DBConnection{
    @Override
    public void getConnection() {
        System.out.println("打开oracle连接");
    }
}

 打印结果

"C:\Program Files\Java\jdk1.6.0_43\bin\java.exe" "-javaagent:D:\java\devolopKit\idea\anZh\IntelliJ IDEA Community Edition 2018.1.4\lib\idea_rt.jar=12553:D:\java\devolopKit\idea\anZh\IntelliJ IDEA Community Edition 2018.1.4\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.6.0_43\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\jce.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\resources.jar;C:\Program Files\Java\jdk1.6.0_43\jre\lib\rt.jar;F:\xiangmu3\Xin\Idea\out\production\design_pattern" com.geely.design.principle.compositionaggregation.TestBizDao
打开MySql连接

Process finished with exit code 0