switch 应该加上@NotNull的注解, 而且不应该用字符串, 用枚举类包装字符串, 避免空指针.

[amosJinCloudwise]

enum DataSourceRegionEnum {
/**
* 数据来源国家或地区
*/
CN,
US,
GB,
UNKNOWN,
UNSUPPORTED;
}

public static void testSwitch(@javax.validation.constraints.NotNull(message = "must be DataSourceRegionEnum, and not null") DataSourceRegionEnum dataSourceRegionEnum) {
    switch (dataSourceRegionEnum) {
        case CN:
            System.out.println(DataSourceRegionEnum.CN);
            break;
        case GB:
            System.out.println(DataSourceRegionEnum.GB);
            break;
        case US:
            System.out.println(DataSourceRegionEnum.US);
            break;
        case UNSUPPORTED:
            throw new RuntimeException("not-supported");
        case UNKNOWN:
            throw new RuntimeException("unknown");
        default:
            System.out.println(DataSourceRegionEnum.CN);
    }
}