教你巧用mysql位运算解决多选值存储的问题

## 例2：判断用户是否开启了密码认证 + 短信认证 (1+2)
Select * from user where auth_method & 3;

## 例2：判断用户是否开启了密码认证 + 短信认证 + 扫码认证 (1+2+4)
Select * from user where auth_method & 7;

import java.util.Arrays;
import java.util.List;

@Getter
public enum AuthMethodEnum {

PASSWORD(1, “密码认证”),
SMS(2, “短信认证”),
QR_CODE(4, “扫码认证”);

private Integer method;

private String name;

AuthMethodEnum(Integer method, String name) {
this.method = method;
this.name = name;
}

/**
* 将mysql存储值解析成多种认证方式
* @param method
* @return
*/
public static List<Integer> parseAuthMethod(Integer method) {
List<Integer> list = Lists.newArrayList();
if (null == method) {
return list;
}
AuthMethodEnum[] arr = AuthMethodEnum.values();
// 需要先将method从大到小排序
Arrays.sort(arr, (o1, o2) -> {
if (o1.method > o2.method) {
return -1;
} else {
return 0;
}
});
for (AuthMethodEnum e : arr) {
if (method >= e.method) {
list.add(e.method);
method = method – e.method;
}
}
return list;
}

/**
* 将任意种认证方式计算后得到存储值
* @param methods
* @return
*/
public static Integer calculateAuthMethod(List<Integer> methods) {
if (CollectionUtils.isEmpty(methods)) {
return 0;
}
return methods.stream().mapToInt(p -> p).sum();
}

public static void main(String[] args) {
System.out.println(parseAuthMethod(8));
}
}