php methods to catch errors: 1. Use the "try{}catch()" method to catch errors; 2. Use the "set_error_handler" function to catch "E_NOTICE", etc.; 3. Use "set_exception_handler" to set the default exception handler.
php error and exception capture
In actual development, error and exception capture only relies on try{}catch () is far from enough.
So quote the following functions.
a) set_error_handler
Generally used to capture E_NOTICE, E_USER_ERROR, E_USER_WARNING, E_USER_NOTICE
Cannot capture:
E_ERROR, E_PARSE, E_CORE_ERROR, E_CORE_WARNING, E_COMPILE_ERROR and E_COMPILE_WARNING.
Generally used in conjunction with trigger_error("...", E_USER_ERROR).
<?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, $b) . "\n";
?>
b) set_exception_handler
Set the default exception handler for exceptions that are not caught with try/catch blocks. Exceptions are aborted after exception_handler is called.
Use together with throw new Exception('Uncaught Exception occurred').
<?php
// we will do our own error handling
error_reporting(0);
function exceptHandle($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
The execution mechanism is: php transfers the function to be called into memory. This function is called again when all PHP statements on the page have been executed.
Generally used in conjunction with trigger_error("...", E_USER_ERROR).
<?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() function
Definition and usage The restore_error_handler() function restores the previous error handler, which was changed by the set_error_handler() function.
This function always returns true.
is the inverse function of set_error_handler().
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