php错误及异常捕捉
在实际开发中，错误及异常捕捉仅仅靠try{}catch()是远远不够的。
所以引用以下几中函数。
a) set_error_handler
一般用于捕捉 E_NOTICE 、E_USER_ERROR、E_USER_WARNING、E_USER_NOTICE
不能捕捉：
E_ERROR, E_PARSE, E_CORE_ERROR, E_CORE_WARNING, E_COMPILE_ERROR and E_COMPILE_WARNING。
一般与trigger_error("...", E_USER_ERROR)，配合使用。
<?php
// we will do our own error handling
error_reporting(0);
function userErrorHandler($errno, $errmsg, $filename, $linenum, $vars)
{
// timestamp for the error entry
$dt = date("Y-m-d H:i:s (T)");
// define an assoc array of error string
// in reality the only entries we should
// consider are E_WARNING, E_NOTICE, E_USER_ERROR,
// E_USER_WARNING and E_USER_NOTICE
$errortype = array (
E_ERROR => 'Error',
E_WARNING => 'Warning',
E_PARSE => 'Parsing Error',
E_NOTICE => 'Notice',
E_CORE_ERROR => 'Core Error',
E_CORE_WARNING => 'Core Warning',
E_COMPILE_ERROR => 'Compile Error',
E_COMPILE_WARNING => 'Compile Warning',
E_USER_ERROR => 'User Error',
E_USER_WARNING => 'User Warning',
E_USER_NOTICE => 'User Notice',
E_STRICT => 'Runtime Notice',
E_RECOVERABLE_ERROR => 'Catchable Fatal Error'
);
// set of errors for which a var trace will be saved
$user_errors = array(E_USER_ERROR, E_USER_WARNING, E_USER_NOTICE);
$err = "<errorentry>\n";
$err .= "\t<datetime>" . $dt . "</datetime>\n";
$err .= "\t<errornum>" . $errno . "</errornum>\n";
$err .= "\t<errortype>" . $errortype[$errno] . "</errortype>\n";
$err .= "\t<errormsg>" . $errmsg . "</errormsg>\n";
$err .= "\t<scriptname>" . $filename . "</scriptname>\n";
$err .= "\t<scriptlinenum>" . $linenum . "</scriptlinenum>\n";
if (in_array($errno, $user_errors)) {
$err .= "\t<vartrace>" . wddx_serialize_value($vars, "Variables") . "</vartrace>\n";
}
$err .= "</errorentry>\n\n";
echo $err;}
function distance($vect1, $vect2) {
if (!is_array($vect1) || !is_array($vect2)) {
trigger_error("Incorrect parameters, arrays expected", E_USER_ERROR);
return NULL;
}
if (count($vect1) != count($vect2)) {
trigger_error("Vectors need to be of the same size", E_USER_ERROR);
return NULL;
}
for ($i=0; $i<count($vect1); $i++) {
$c1 = $vect1[$i]; $c2 = $vect2[$i];
$d = 0.0;
if (!is_numeric($c1)) {
trigger_error("Coordinate $i in vector 1 is not a number, using zero",E_USER_WARNING);
$c1 = 0.0;
}
if (!is_numeric($c2)) {
trigger_error("Coordinate $i in vector 2 is not a number, using zero",E_USER_WARNING);
$c2 = 0.0;
}
$d += $c2*$c2 - $c1*$c1;
}
return sqrt($d);}
$old_error_handle = set_error_handler("userErrorHandler");
$t = I_AM_NOT_DEFINED; //generates a warning
// define some "vectors"
$a = array(2, 3, "foo");
$b = array(5.5, 4.3, -1.6);
$c = array(1, -3);
//generate a user error
$t1 = distance($c,$b);
// generate another user error
$t2 = distance($b, "i am not an array") . "\n";
// generate a warning
$t3 = distance($a, $b) . "\n";
?>
b) set_exception_handler
设置默认的异常处理程序，用于没有用 try/catch 块来捕获的异常。 在 exception_handler 调用后异常会中止。
与throw new Exception('Uncaught Exception occurred')，连用。
<?php
// we will do our own error handling
error_reporting(0);
function exceptHandle($errno, $errmsg, $filename, $linenum, $vars)
{
// timestamp for the error entry
$dt = date("Y-m-d H:i:s (T)");
// define an assoc array of error string
// in reality the only entries we should
// consider are E_WARNING, E_NOTICE, E_USER_ERROR,
// E_USER_WARNING and E_USER_NOTICE
$errortype = array (
E_ERROR => 'Error',
E_WARNING => 'Warning',
E_PARSE => 'Parsing Error',
E_NOTICE => 'Notice',
E_CORE_ERROR => 'Core Error',
E_CORE_WARNING => 'Core Warning',
E_COMPILE_ERROR => 'Compile Error',
E_COMPILE_WARNING => 'Compile Warning',
E_USER_ERROR => 'User Error',
E_USER_WARNING => 'User Warning',
E_USER_NOTICE => 'User Notice',
E_STRICT => 'Runtime Notice',
E_RECOVERABLE_ERROR => 'Catchable Fatal Error'
);
// set of errors for which a var trace will be saved
$err = "<errorentry>\n";
$err .= "\t<datetime>" . $dt . "</datetime>\n";
$err .= "\t<errornum>" . $errno . "</errornum>\n";
$err .= "\t<errortype>" . $errortype[$errno] . "</errortype>\n";
$err .= "\t<errormsg>" . $errmsg . "</errormsg>\n";
$err .= "\t<scriptname>" . $filename . "</scriptname>\n";
$err .= "\t<scriptlinenum>" . $linenum . "</scriptlinenum>\n";
if (1) {
$err .= "\t<vartrace>" . wddx_serialize_value($vars, "Variables") . "</vartrace>\n";
}
$err .= "</errorentry>\n\n";
echo $err;}
$old_except_handle = set_exception_handler("exceptHandle");
//$t = I_AM_NOT_DEFINED; //generates a warning
$a;
throw new Exception('Uncaught Exception occurred');
?>
c) register_shutdown_function
执行机制是：php把要调用的函数调入内存。当页面所有ＰＨＰ语句都执行完成时，再调用此函数。
一般与trigger_error("...", E_USER_ERROR)，配合使用。
<?php
error_reporting(0);
date_default_timezone_set('Asia/Shanghai');
register_shutdown_function('my_exception_handler');
$t = I_AM_NOT_DEFINED; //generates a warning
trigger_error("Vectors need to be of the same size", E_USER_ERROR);
function my_exception_handler()
{
if($e = error_get_last()) {
//$e['type']对应php_error常量
$message = '';
$message .= "出错信息:\t".$e['message']."\n\n";
$message .= "出错文件:\t".$e['file']."\n\n";
$message .= "出错行数:\t".$e['line']."\n\n";
$message .= "\t\t请工程师检查出现程序".$e['file']."出现错误的原因\n";
$message .= "\t\t希望能您早点解决故障出现的原因<br/>";
echo $message;
//sendemail to
}}
?>
c) restore_error_handler()函数
定义和用法 restore_error_handler() 函数恢复之前的错误处理程序，该程序是由 set_error_handler() 函数改变的。
该函数永远返回 true。
是 set_error_handler()的反函数。
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