用两种方式在springboot项目中实现适配器模式

1. 场景

当我们后台有两个数据库，分别为mysql和oracle，根据前端参数中的数据库类型字段，去查询对应sql语句

2. 方式1，通过实现类定义类型字段实现

2.1 创建接口

public interface DbService {/*** 获取数据库类型* @return*/String getDbType();/*** 查询数据库sql* @return*/String getDbSql();
}

2.2 创建mysql实现类

@Service
public class MysqlDbService implements DbService{@Overridepublic String getDbType() {return "mysql";}@Overridepublic String getDbSql() {return "获取mysql的SQL";}
}

2.3 创建oracle实现类

@Service
public class OracleSDbService implements DbService{@Overridepublic String getDbType() {return "oracle";}@Overridepublic String getDbSql() {return "获取oracle的SQL";}
}

2.4 创建接口,在接口中注入service集合，根据每个实现类中定义的dbType进行匹配后进行调用

@RestController
@RequestMapping("/test")
public class TestController {@Resourceprivate List<DbService> dbServiceList;@GetMapping("/getDbSql1")public String getDbSql(@RequestParam String dbtype){DbService dbService = dbServiceList.stream().filter(item -> dbtype.equals(item.getDbType())).findFirst().get();return dbService.getDbSql();}}

2.5 测试，浏览器输入

3. 方式2，以动态service名称的方式实现

3.1 创建接口

public interface DbService {/*** 获取数据库类型* @return*/String getDbType();/*** 查询数据库sql* @return*/String getDbSql();
}

3.2 创建创建mysql实现类，定义实现类名称为mysqlDbService

@Service(value = "mysqlDbService")
public class MysqlDbService implements DbService{@Overridepublic String getDbType() {return "mysql";}@Overridepublic String getDbSql() {return "获取mysql的SQL";}
}

3.3 创建创建oracle实现类，定义实现类名称为oracleDbService

@Service(value = "oracleDbService")
public class OracleSDbService implements DbService{@Overridepublic String getDbType() {return "oracle";}@Overridepublic String getDbSql() {return "获取oracle的SQL";}
}

3.4 引入ApplicationContext，获取service方法名

@Component("applicationContextHelper")
public class ApplicationContextHelper implements ApplicationContextAware {private static ApplicationContext applicationContext;public static <T> T popBean(String name, Class<T> clazz) {if (applicationContext == null) {return null;}return applicationContext.getBean(name, clazz);}@Overridepublic void setApplicationContext(ApplicationContext context) throws BeansException {applicationContext = context;}public ApplicationContext getInstance() {return applicationContext;}
}

3.5 调用接口，通过ApplicationContextHelper根据service名称动态获取实现类，调用方法

@RestController
@RequestMapping("/test")
public class TestController {@Resourceprivate List<DbService> dbServiceList;@GetMapping("/getDbSql2")public String getDbSql2(@RequestParam String dbtype){DbService dbService = ApplicationContextHelper.popBean(dbtype + "DbService", DbService.class);return dbService.getDbSql();}
}

3.6 测试