判断一个字符串是否为IP地址

private boolean isIpAddress(String value) {

int start = 0;
int end = value.indexOf('.');
int numBlocks = 0;

while (start < value.length()) {

if (end == -1) {
end = value.length();
}

try {
int block = Integer.parseInt(value.substring(start, end));
if ((block > 255) || (block < 0)) {
return false;
}
} catch (NumberFormatException e) {
return false;
}

numBlocks++;

start = end + 1;
end = value.indexOf('.', start);
}

return numBlocks == 4;
}