Summary of PHP errors and exceptions
- 高洛峰Original
- 2016-10-20 14:07:171300browse
Error
Error level
Fatal Error: Fatal error (script terminates execution)
E_ERROR Fatal runtime fatal error, terminating program execution
E_CORE_ERROR PHP fatal error at startup
E_COMPILE_ERROR PHP compilation fatal error
E_USER_ERR OR Fatal errors generated by users
Parse Error: Parsing error during compilation (script terminates execution)
Parse Error Syntax parsing error during compilation
Warning Error: Warning error (only prompt information is given, but the script does not Terminate the run.)
E_WARNING Runtime warning (non-fatal error).
E_CORE_WARNING Warning (non-fatal error) that occurs during PHP initialization startup.
E_COMPILE_WARNING Compilation warning
E_USER_WARNING User-generated warning information
Notice Error: Notification error (only notification information is given, but the script will not terminate the run.)
E_NOTICE Runtime notification. Indicates that the script encounters a situation that may appear as an error.
E_USER_NOTICE Notification information generated by the user.
set_error_handler() captures errors [with limitations]
Function description
set_error_handler($callback);//Set a user function (error_handler) to handle errors that occur in the script.
Limitations of functions
The following levels of errors cannot be handled by user-defined functions: E_ERROR, E_PARSE, E_CORE_ERROR, E_CORE_WARNING, E_COMPILE_ERROR, E_COMPILE_WARNING, and most E_STRICTs generated in the file where the set_error_handler() function is called.
That is: set_error_handler($callback) can only capture some Warning and Notice level Errors generated by the system.
Usage
<?phpset_error_handler("error_handler");function error_handler($errno,$errstr,$errfile,$errline){ $str=<<<EOF "errno":$errno
"errstr":$errstr
"errfile":$errfile
"errline":$errlineEOF;
//获取到错误可以自己处理，比如记Log、报警等等 echo $str;
}echo $test;//$test未定义，会报一个notice级别的错误Output result:
"errno":8"errstr":Undefined variable: test"errfile":/Users/shuchao/Desktop/handler.php"errline":13 如何捕获PHP的Fatal Error、Parse Error等
Requirement description
Get PHP's fatal error, such as recording it in the Log, which helps us analyze online problems and monitor online services.
Two functions
register_shutdown_function()
register_shutdown_function($callback)
register_shutdown_function(), put the function you want to register into [pretend to be a queue], wait until the script exits normally or displays the exit call , and then pull out the registered function for execution.
Three situations when register_shutdown_function() is called:
When the script exits normally;
When the script exits with an error (run-time not parse-time);
User When calling the exit method to exit.
error_get_last()
error_get_last();//The function gets the last error that occurred.
This function returns the last error that occurred in the form of an array.
The returned array contains 4 keys and values:
[type] - error type
[message] - error message
[file] - the file where the error occurred
[line] - the line where the error occurred
Use Method
<?php
register_shutdown_function( "fatal_handler" );
define('E_FATAL', E_ERROR | E_USER_ERROR | E_CORE_ERROR |
E_COMPILE_ERROR | E_RECOVERABLE_ERROR| E_PARSE );function fatal_handler() { if( $error = error_get_last()) { $errno = $error["type"]; $errfile = $error["file"]; $errline = $error["line"]; $errstr = $error["message"]; $str=<<<EOF "errno":$errno
"errstr":$errstr
"errfile":$errfile
"errline":$errlineEOF;
//获取到错误可以自己处理，比如记Log、报警等等 echo $str;
}
}Strongly note
that the register_shutdown_function() function will not be called when parse-time error occurs. Register_shutdown_function() will be called only when a run-time error occurs.
Let’s give an example below:
NO.1
error_handler.php
<?phpregister_shutdown_function("error_handler");function error_handler(){ echo "Yeah,it's worked!";
}function test(){}function test(){}The execution results are as follows:
Fatal error: Cannot redeclare test() (previously declared in /Users/shuchao/Desktop/error_handler.php:6 ) in/Users/shuchao/Desktop/error_handler.php on line 7
Cause analysis
When executing error_handler.php, due to the repeated definition of two functions test(), an error occurred in the parse-time of php (not run-time), so the function in register_shutdown_function() cannot be called back.
NO.2
error_handler.php
<?phpregister_shutdown_function("error_handler");function error_handler(){ echo "Yeah,it's worked!";
}if(true){ function test(){}
}function test(){}The execution results are as follows:
Fatal error: Cannot redeclare test() (previously declared in /Users/shuchao/Desktop/error_handler.php:9) in /Users/shuchao/Desktop/error_handler.php on line 7Yeah,it's worked!%
Cause analysis
我们看到，上面回调了register_shutdown_function().
因为我们加了一个if()判断，if()里面的test()方法，相当于一个闭包，与外面的test()名称不冲突。
也就是，上面的代码在parse-time没有出错，而是在run-time的时候出错了，所以我们能够获取到fatal error。
NO.3
error_handler.php
<?phpregister_shutdown_function("error_handler");function error_handler(){ echo "Yeah,it's worked!";}
test_error.php
<?phpinclude './error_handler.php';function test(){}function test(){}执行 test_error.php的结果如下
Fatal error: Cannot redeclare test() (previously declared in /Users/shuchao/Desktop/test_error.php:3) in/Users/shuchao/Desktop/test_error.php on line 4
原因分析
当我们在运行test_error.php的时候,因为redeclare了两个test()方法，所以php的语法解析器在parse-time的时候就出错了。 所以不能回调register_shutdown_function()中的方法，不能catch住这个fatal error。
NO.4
error_handler.php
<?phpregister_shutdown_function("error_handler");function error_handler(){ echo "Yeah,it's worked!";}
test_error.php
<?phpfunction test(){}function test(){}
include_all.php
require './error_handler.php';require './test_error.php';执行 include_all.php的结果如下
Fatal error: Cannot redeclare test() (previously declared in /Users/shuchao/Desktop/include_all.php:2) in /Users/shuchao/Desktop/include_all.php on line 3Yeah,it's worked!%
结果分析
上面我们捕获了fatal_error.因为在运行include_all.php的时候，include_all.php本身语法并没有出错，也就是在parse-time的时候并没有出错，而是include的文件出错了，也就是在run-time的时候出错了，这个时候是能回调register_shutdown_function()中的函数的。
强烈建议：如果我们要使用register_shutdown_function进行错误捕捉，使用NO.4，最后一种方法，可以确保错误都能捕捉到。
更优美的写法·获取所有错误
set_error_handler()与register_shutdown_function()、error_get_last()的结合使用
<?phpregister_shutdown_function( "fatal_handler" );set_error_handler("error_handler");define('E_FATAL', E_ERROR | E_USER_ERROR | E_CORE_ERROR | E_COMPILE_ERROR | E_RECOVERABLE_ERROR| E_PARSE );//获取fatal errorfunction fatal_handler() { $error = error_get_last(); if($error && ($error["type"]===($error["type"] & E_FATAL))) { $errno = $error["type"]; $errfile = $error["file"]; $errline = $error["line"]; $errstr = $error["message"]; error_handler($errno,$errstr,$errfile,$errline); }}//获取所有的errorfunction error_handler($errno,$errstr,$errfile,$errline){ $str=<<<EOF "errno":$errno "errstr":$errstr "errfile":$errfile "errline":$errlineEOF;//获取到错误可以自己处理，比如记Log、报警等等 echo $str;}
Exception
Exception与Error的区别
Exception当异常抛出的时候，我们是想要去捕获他，并去做处理的。所以异常经常被当做程序的控制流程使用。
Error
Error是不可恢复的，是在开发过程中要去解决的。
使用Exception的例子
我想执行insert语句插入一条数据，可能插入失败(比如ID重复)，注意是可能失败，所以这是一个可能的情况，也就是异常情况。我们就可以使用异常来处理这个问题
try { $row->insert(); $inserted = true;
} catch (Exception $e) { echo "There was an error inserting the row - ".$e->getMessage(); $inserted = false;
}echo "Some more stuff";如何catch一个未捕获的Exception
场景描述
假设程序中的有些地方直接throw了异常，没有进行catch。我们现在想要不管在程序的任何一个地方throw异常，即便在throw的地方没有被catch，我们也要能catch住，如何做到呢？
一个函数:set_exception_handler()
//设置默认的异常处理程序，用于没有用 try/catch 块来捕获的异常。 在 exception_handler 调用后异常会中止。
set_exception_handler()
使用示例
1、exception_handler.php
<?phpset_exception_handler("my_exception");function my_exception($exception){ echo $exception->getMessage();}
2、test_exception.php
<?phprequire "./exception_handler.php";throw new Exception("I am Exception");现在我们运行 test_exception.php，结果如下：
I am Exception //证明我们throw的Exception被捕获了