java.lang.IllegalStateException: stream has already been operated upon or closed

Stream 只能被使用一次 

DoubleStream ds = channelOrderList.stream().mapToDouble(o -> o.getPrincipal().doubleValue());
double sum = ds.sum();
long count = ds.count();

所以代码修改为

double sum = channelOrderList.stream().mapToDouble(o -> o.getPrincipal().doubleValue()).sum();

long count = channelOrderList.stream().mapToDouble(o -> o.getPrincipal().doubleValue()).count();