最近写的一个 .NET Core 爬虫里用到了需要多次重试的功能，本着无脑输出的精神，google 了一下，还真给我找到了：
public static T Retry<T, TException>(int timesToRetry, Func<int, T> thingToTry) where TException : Exception {
// Start at 1 instead of 0 to allow for final attempt
int i;
for (i = 1; i < timesToRetry; i++) {
try {
return thingToTry(i);
}
catch (TException) {
// Maybe: Trace.WriteLine("Failed attempt...");
}
}
return thingToTry(i); // Final attempt, let exception bubble up
}
//这里我增加了个异步版本
public static async Task<T> RetryAsync<T, TException>(int timesToRetry, Func<int, Task<T>> thingToTry) where TException : Exception {
// Start at 1 instead of 0 to allow for final attempt
int i;
for (i = 1; i < timesToRetry; i++) {
try {
return await thingToTry(i);
}
catch (TException) {
// Maybe: Trace.WriteLine("Failed attempt...");
}
}
return await thingToTry(i); // Final attempt, let exception bubble up
}
用法就很简单了：
using static AStaticClass;
class A {
void B() {
//重试 3 次
var result = Retry<int, Exception>(3, nTimes => {
//这里做需要重试的事情
Console.WriteLine($"第 {nTimes} 次尝试");
return 99999;
});
}
}
可惜当时看到的时候顺手关了浏览器，找不到原始出处了，等我找回来补上。