Introduction to the detailed method of exception handling in php5 programming

1. First of all, try, catch

<?php 
$path = "D:\\\\"; 
try //Detection of exception
{ 
file_open($path); 
} 
catch(Exception $e)//Catch exception
{ 
echo $e->getMessage(); 
} 

function file_open($path) 
{ 
if(!file_exists($path))//If the file cannot be found, throw an exception object
{ 
throw new Exception("File cannot be found", 1);
} 

if(!fopen($path, "r"))//If the file cannot be opened, throw an exception object
{ 
throw new Exception("File cannot be opened", 2);
} 
} 
?> 
Pay attention to using $e->getMessage() to output exception information.

2 Output exception complete information

<?php 
$path = "D:\\\\"; 

try 
{ 
file_open($path);//Try to open the file
} 
catch(Exception $e) 
{ 
echo "Exception information: ".$e->getMessage()."\\n"; //Return user-defined exception information
echo "Exception code: ".$e->getCode()."\\n"; //Return the user-defined exception code
echo "File name: ".$e->getFile()."\\n"; //Return the PHP program file name where the exception occurred
echo "The line where the exception code is located".$e->getLine()."\\n"; //Return the line number of the line where the exception code is located.
echo “Delivery route:”;
print_r($e->getTrace()); //Return the route passed in each step of the tracking exception in the form of an array.
echo $e->getTraceAsString(); //Return the getTrace function information formatted into a string
} 

function file_open($path) 
{ 
if(!file_exists($path))//If the file does not exist, an error is thrown.
{ 
throw new Exception("File cannot be found", 1);
} 

if(!fopen($path, "r")) 
{ 
throw new Exception("File cannot be opened", 2);
} 
} 
?> 




Extended exception, that is, custom exception

<?php 
class FileExistsException extends Exception{} //Class used to deal with files that do not have exceptions
class FileOpenException extends Exception{} //Class used to handle file unreadable exceptions

$path = "D:\\\\"; 

try 
{ 
file_open($path); 
} 
catch(FileExistsException $e)//If a FileExistsException exception is generated, the user will be prompted to confirm the file location.
{ 
echo "Exception occurred during the program: ".$e->getMessage()."\\n";
echo "Please confirm the file location.";
} 
catch(FileOpenException $e)//If a FileOpenException exception is generated, the user will be prompted to confirm the readability of the file.
{ 
echo "Exception occurred during the program: ".$e->getMessage()."\\n";
echo "Please confirm the readability of the file.";
} 
catch(Exception $e) 
{ 
echo "[Unknown exception]";
echo "Exception information: ".$e->getMessage()."\\n"; //Return user-defined exception information
echo "Exception code: ".$e->getCode()."\\n"; //Return the user-defined exception code
echo "File name: ".$e->getFile()."\\n"; //Return the PHP program file name where the exception occurred
echo "The line where the exception code is located".$e->getLine()."\\n"; //Return the line number of the line where the exception code is located.
echo “Delivery route:”;
print_r($e->getTrace()); //Return the route passed in each step of the tracking exception in the form of an array.
echo $e->getTraceAsString(); //Return the getTrace function information formatted into a string
} 

function file_open($path) 
{ 
if(!file_exists($path)) 
{ 
throw new FileExistsException("File cannot be found", 1); //Top the FileExistsException exception object
} 

if(!fopen($path, "r")) 
{ 
throw new FileOpenException("File cannot be opened", 2); //Top the FileOpenException exception object

} 
} 
?> 

4 Resell the exception to the upper level

<?php 
class FileExistsException extends Exception{} //Class used to deal with files that do not have exceptions
class FileOpenException extends Exception{} //Class used to handle file unreadable exceptions

$path = "D:\\\\"; 

try 
{ 
file_open($path); 
} 
catch(FileExistsException $e)//If a FileExistsException exception is generated, the user will be prompted to confirm the file location.
{ 
echo "Exception occurred during the program: ".$e->getMessage()."\\n";
echo "Please confirm the file location.";
} 
catch(FileOpenException $e)//If a FileOpenException exception is generated, the user will be prompted to confirm the readability of the file.
{ 
echo "Exception occurred during the program: ".$e->getMessage()."\\n";
echo "Please confirm the readability of the file.";
} 
catch(Exception $e) 
{ 
echo "[Unknown exception]";
echo "Exception information: ".$e->getMessage()."\\n"; //Return user-defined exception information
echo "Exception code: ".$e->getCode()."\\n"; //Return the user-defined exception code
echo "File name: ".$e->getFile()."\\n"; //Return the PHP program file name where the exception occurred
echo "The line where the exception code is located".$e->getLine()."\\n"; //Return the line number of the line where the exception code is located.
echo “Delivery route:”;
print_r($e->getTrace()); //Return the route passed in each step of the tracking exception in the form of an array.
echo $e->getTraceAsString(); //Return the getTrace function information formatted into a string
} 

function file_open($path) 
{ 
try 
{ 
if(!file_exists($path)) 
{ 
throw new FileExistsException("File cannot be found", 1);
} 

if(!fopen($path, "r")) 
{ 
throw new FileOpenException("File cannot be opened", 2);
} 
} 
catch(Exception $e)//Catch exception
{ 
echo "Exception occurred during operation of file_open function";
throw $e; //Rethrow exception
} 
} 
?>