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:
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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