import java.io.Serializable;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
interface IConnection {
public void query(String sql);
}
interface IDriver {
public DIALECT getDialect();
public IConnection getConnection();
}
public class Bridge {
public static void main(String[] args) {
DriverManager.registerDriver(new MySqlDriver());
IConnection mysql = DriverManager.getConnection();
mysql.query("select * from table");
DriverManager.registerDriver(new OracleDriver());
IConnection oracle = DriverManager.getConnection(DIALECT.ORACLE);
oracle.query("insert into table");
IConnection db2 = DriverManager.getConnection(DIALECT.DB2);
db2.query("update table");
}
}
enum DIALECT implements Serializable {
MYSQL,ORACLE,DB2;
}
class DriverManager {
private static Map<DIALECT, IDriver> drivers =
new ConcurrentHashMap<DIALECT, IDriver>();
private static final DIALECT DEFAULT_DIALECT = DIALECT.MYSQL;
private DriverManager() { }
public static void registerDriver(IDriver driver) {
drivers.put(driver.getDialect(), driver);
}
public static IConnection getConnection() {
return getConnection(DEFAULT_DIALECT);
}
public static IConnection getConnection(DIALECT dialect) {
IDriver driver = drivers.get(dialect);
if (driver == null)
throw new IllegalArgumentException("no driver register with " + dialect);
return driver.getConnection();
}
}
class MySqlDriver implements IDriver {
@Override public IConnection getConnection() {
return new IConnection() {
@Override public void query(String sql) {
System.out.println("MySql query ('" + sql + "') is executing......");
}
};
}
@Override public DIALECT getDialect() {
return DIALECT.MYSQL;
}
}
class OracleDriver implements IDriver {
@Override public IConnection getConnection() {
return new IConnection() {
@Override public void query(String sql) {
System.out.println("Oracle query ('" + sql + "') is executing......");
}
};
}
@Override public DIALECT getDialect() {
return DIALECT.ORACLE;
}
}
class DB2Driver implements IDriver {
@Override public IConnection getConnection() {
return new IConnection() {
@Override public void query(String sql) {
System.out.println("DB2 query ('" + sql + "') is executing......");
}
};
}
@Override public DIALECT getDialect() {
return DIALECT.DB2;
}
}
输出为:
MySql query ('select * from table') is executing......
Oracle query ('insert into table') is executing......
Exception in thread "main" java.lang.IllegalArgumentException: no driver register with DB2
* jdbc api使用bridge模式 Service / DAO
* bridge是在设计之初的模式,adapter是针对已有系统的代码。
* 通过对象组合的方式,Bridge模式把两个角色之间的继承关系改为了耦合的关系,从而使这两者可以
从容自若的各自独立的变化,这也是Bridge模式的本意。
public abstract class Abstraction {
protected Implementor implementor;
public Abstraction(Implementor implementor) {
this.implementor = implementor;
}
public void operation() {
implementor.operationImpl();
}
}
public interface Implementor {
public void operationImpl();
}
class ConcreteImplementorA implements Implementor {
@Override public void operationImpl() {
// 真正的实现
System.out.println("具体实现A");
}
}
class ConcreteImplementorB implements Implementor {
@Override public void operationImpl() {
// 真正的实现
System.out.println("具体实现B");
}
}
class RefinedAbstraction extends Abstraction {
public RefinedAbstraction(Implementor implementor) {
super(implementor);
}
@Override public void operation() {
//do someting
super.operation();
//do other thing
}
}
* Facade模式注重简化接口,Adapter模式注重转换接口,Bridge模式注重分离接口(抽象)与其实现,
Decorator模式注重稳定接口的前提下为对象扩展功能。