common_helper/src/main/java/com/xiongyingqi/util/DomainHelper.java
public static String removeDomain(String str) {
        if (str != null && !"".equals(str)) {
            int index = str.indexOf("@");
            if (index >= 0) {
                str = str.substring(0, index);
            }
        }
        return str;
    }
public static String removeDomain(String str) {
        if (str != null && !"".equals(str)) {
            int index = str.indexOf("@");
            if (index >= 0) {
                str = str.substring(0, index);
            }
        }
        return str;
    }
public static String removeDomain ( String str ) { if ( str != null && ! "" . equals ( str ) ) { int index = str . indexOf ( "@" ) ; if ( index >= 0 ) { str = str . substring ( 0 , index ) ; } } return str ; }
移除主机字符，例如传入admin@xiongyingqi.com，那么该方法将截取@之前的字符返回admin

@param str
@return
移除主机字符，例如传入admin@xiongyingqi . com，那么该方法将截取@之前的字符返回admin