二十三种设计模式全面解析-适配器模式的妙用：异构数据库和不同版本API的完美兼容！

// 目标接口
interface Database {
    void connect();
    void query(String sql);
}
// MySQL数据库类
class MySQLDatabase {
    public void establishConnection() {
        System.out.println("Establishing connection to MySQL database...");
        // 实际的连接逻辑
    }
    public void executeQuery(String sql) {
        System.out.println("Executing MySQL query: " + sql);
        // 实际的查询逻辑
    }
}
// Oracle数据库类
class OracleDatabase {
    public void connectToDatabase() {
        System.out.println("Connecting to Oracle database...");
        // 实际的连接逻辑
    }
    public void executeSQL(String sql) {
        System.out.println("Executing Oracle SQL: " + sql);
        // 实际的查询逻辑
    }
}
// MySQL适配器类
class MySQLAdapter implements Database {
    private MySQLDatabase mySQLDatabase;
    public MySQLAdapter(MySQLDatabase mySQLDatabase) {
        this.mySQLDatabase = mySQLDatabase;
    }
    public void connect() {
        mySQLDatabase.establishConnection();
    }
    public void query(String sql) {
        mySQLDatabase.executeQuery(sql);
    }
}
// Oracle适配器类
class OracleAdapter implements Database {
    private OracleDatabase oracleDatabase;
    public OracleAdapter(OracleDatabase oracleDatabase) {
        this.oracleDatabase = oracleDatabase;
    }
    public void connect() {
        oracleDatabase.connectToDatabase();
    }
    public void query(String sql) {
        oracleDatabase.executeSQL(sql);
    }
}
// 客户端代码
public class Main {
    public static void main(String[] args) {
        Database mysql = new MySQLAdapter(new MySQLDatabase());
        mysql.connect();
        mysql.query("SELECT * FROM users");
        Database oracle = new OracleAdapter(new OracleDatabase());
        oracle.connect();
        oracle.query("SELECT * FROM customers");
    }
}

// 目标接口
interface ExternalAPI {
    void performOperation();
}
// API v1类
class APIv1 {
    public void doOperation() {
        System.out.println("Performing operation in API v1...");
        // 实际的操作逻辑
    }
}
// API v2类
class APIv2 {
    public void executeOperation() {
        System.out.println("Executing operation in API v2...");
        // 实际的操作逻辑
    }
}
// API v1适配器类
class APIv1Adapter implements ExternalAPI {
    private APIv1 apiv1;
    public APIv1Adapter(APIv1 apiv1) {
        this.apiv1 = apiv1;
    }
    public void performOperation() {
        apiv1.doOperation();
    }
}
// API v2适配器类
class APIv2Adapter implements ExternalAPI {
    private APIv2 apiv2;
    public APIv2Adapter(APIv2 apiv2) {
        this.apiv2 = apiv2;
    }
    public void performOperation() {
        apiv2.executeOperation();
    }
}
// 客户端代码
public class Main {
    public static void main(String[] args) {
        ExternalAPI api1 = new APIv1Adapter(new APIv1());
        api1.performOperation();
        ExternalAPI api2 = new APIv2Adapter(new APIv2());
        api2.performOperation();
    }
}