Java设计模式之桥接模式详解

技术笔记 Java

发布日期: 2025-02-23

更新日期: 2025-02-24

文章字数: 1.1k

阅读时长: 4 分

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什么是桥接模式？

桥接模式（Bridge Pattern）是一种结构型设计模式，它将抽象部分与实现部分分离，使它们都可以独立地变化。这种模式通过组合的方式来替代继承，降低了类与类之间的耦合度。

为什么使用桥接模式？

避免类爆炸性增长
实现抽象和实现的分离
提高系统的可扩展性
实现细节对客户透明

实现示例

1. 基本实现

// 实现接口
public interface DrawAPI {
    void drawCircle(int radius, int x, int y);
}

// 具体实现类A
public class RedCircle implements DrawAPI {
    @Override
    public void drawCircle(int radius, int x, int y) {
        System.out.println("Drawing Circle[ color: red, radius: " + radius + 
                          ", x: " + x + ", y: " + y + "]");
    }
}

// 具体实现类B
public class GreenCircle implements DrawAPI {
    @Override
    public void drawCircle(int radius, int x, int y) {
        System.out.println("Drawing Circle[ color: green, radius: " + radius + 
                          ", x: " + x + ", y: " + y + "]");
    }
}

// 抽象类
public abstract class Shape {
    protected DrawAPI drawAPI;
    
    protected Shape(DrawAPI drawAPI) {
        this.drawAPI = drawAPI;
    }
    
    public abstract void draw();
}

// 扩展抽象类
public class Circle extends Shape {
    private int x, y, radius;
    
    public Circle(int x, int y, int radius, DrawAPI drawAPI) {
        super(drawAPI);
        this.x = x;
        this.y = y;
        this.radius = radius;
    }
    
    @Override
    public void draw() {
        drawAPI.drawCircle(radius, x, y);
    }
}

2. 实际应用示例：消息发送系统

// 消息接口
public interface MessageImplementor {
    void send(String message, String toUser);
}

// 短信实现
public class SmsMessage implements MessageImplementor {
    @Override
    public void send(String message, String toUser) {
        System.out.println("使用短信发送消息：" + message + " 到用户：" + toUser);
    }
}

// 邮件实现
public class EmailMessage implements MessageImplementor {
    @Override
    public void send(String message, String toUser) {
        System.out.println("使用邮件发送消息：" + message + " 到用户：" + toUser);
    }
}

// 抽象消息类
public abstract class AbstractMessage {
    protected MessageImplementor implementor;
    
    public AbstractMessage(MessageImplementor implementor) {
        this.implementor = implementor;
    }
    
    public abstract void sendMessage(String message, String toUser);
}

// 普通消息
public class CommonMessage extends AbstractMessage {
    public CommonMessage(MessageImplementor implementor) {
        super(implementor);
    }
    
    @Override
    public void sendMessage(String message, String toUser) {
        // 可以添加普通消息的处理逻辑
        implementor.send(message, toUser);
    }
}

// 紧急消息
public class UrgentMessage extends AbstractMessage {
    public UrgentMessage(MessageImplementor implementor) {
        super(implementor);
    }
    
    @Override
    public void sendMessage(String message, String toUser) {
        message = "【紧急】" + message;
        implementor.send(message, toUser);
    }
}

3. JDBC中的桥接模式示例

// 数据库驱动接口
public interface Driver {
    Connection connect(String url, Properties info);
}

// MySQL驱动实现
public class MySQLDriver implements Driver {
    @Override
    public Connection connect(String url, Properties info) {
        // MySQL连接实现
        return new MySQLConnection();
    }
}

// Oracle驱动实现
public class OracleDriver implements Driver {
    @Override
    public Connection connect(String url, Properties info) {
        // Oracle连接实现
        return new OracleConnection();
    }
}

// 抽象数据库操作类
public abstract class Database {
    protected Driver driver;
    
    public Database(Driver driver) {
        this.driver = driver;
    }
    
    public abstract void executeQuery(String sql);
}

// 具体数据库操作类
public class BusinessDatabase extends Database {
    public BusinessDatabase(Driver driver) {
        super(driver);
    }
    
    @Override
    public void executeQuery(String sql) {
        Connection conn = driver.connect("jdbc:db://localhost:3306", new Properties());
        // 执行查询
    }
}

4. 使用示例

public class Client {
    public static void main(String[] args) {
        // 绘图示例
        Shape redCircle = new Circle(100, 100, 10, new RedCircle());
        Shape greenCircle = new Circle(100, 100, 10, new GreenCircle());
        
        redCircle.draw();
        greenCircle.draw();
        
        // 消息发送示例
        AbstractMessage commonSms = new CommonMessage(new SmsMessage());
        commonSms.sendMessage("你好", "张三");
        
        AbstractMessage urgentEmail = new UrgentMessage(new EmailMessage());
        urgentEmail.sendMessage("系统异常", "管理员");
    }
}