测试通过代码：
package t0825;
public class Power {
public static void main(String[] args){
System.out.println(Power(2.5,3));
System.out.println(Power(0.00000001,3));
System.out.println(Power(0.00000001,-3));
System.out.println(Power(2,-3));
System.out.println(Power(10,10));
}
/*
* 大数问题
*/
public static double Power(double base, int exponent) {
double result=1.0;
if(equal(base,0.0) && exponent<0){ //当基于为零时，多少次方都为零
return 0.0;
}
int absExponent=0;
if(exponent<0)
absExponent=-exponent; //如果为负数，取反求倒数；
else
absExponent=exponent;
result = PowerAlthmn(base,absExponent);
if(exponent<0)
result = 1.0/result;
return result;
}
public static boolean equal(double num1,double num2){
if((num1-num2)>-0.0000001 && (num1-num2<0.0000001))
return true;
else
return false;
}
public static double PowerAlthmn(double base,int exponent){
double result1=1.0;
while(exponent!=0){
result1=result1*base;
exponent--;
}
return result1;
}
}