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何时ThreadLocal优先于局部变量？(When is ThreadLocal preferred over Local Variables?)

 Java中的ThreadLocal说：  
 
  Java中的ThreadLocal类使您可以创建只能由同一线程读取和写入的变量。 因此，即使两个线程正在执行相同的代码，并且代码具有对ThreadLocal变量的引用，那么这两个线程也看不到彼此的ThreadLocal变量。  
 
 我的问题是：当我们需要获取一个特定于线程的变量时，我们不能只将该变量声明为方法中的局部变量吗？ 因为每个线程都有自己的堆栈，因此它获得了自己的变量副本。 我在这里错过了什么吗？ 

ThreadLocal in Java says that: 
 
 The ThreadLocal class in Java enables you to create variables that can only be read and written by the same thread. Thus, even if two threads are executing the same code, and the code has a reference to a ThreadLocal variable, then the two threads cannot see each other's ThreadLocal variables. 
 
My question is: When we need to get a variable specific to a thread, can't we just declare that variable as a local variable inside a method? Because every thread has its own stack and thus it gets its own copy of variables. Am I missing something here?

原文：https://stackoverflow.com/questions/38448292

更新时间：2023-10-28 09:10

最满意答案

 最好的解决方案是在服务器端安装denver并使用PHP代码。  
 这是js文件中的代码。  
  deleteNewsItem: function(newsId, callback, scope) {
     var dataPath = this.dataPath;
      $.getJSON(dataPath + '/delete-news.php?id='+newsId, function(rawHeadlines) { 
         var headlines = [];
         $.each(rawHeadlines, function(index, rawHeadline) {
            headlines.push(rawHeadline.id);
        } 
     });
             if (callback) {
             callback.call(scope, headlines);
     }
     };
 
 这是“delete_news.php”文件中的代码。  
<?php

$deleteId = isset($_GET['id'])?$_GET['id']:false;
   if ($deleteId){
     $content = file_get_contents('delete-news.json');
     $json = json_decode($content);

$newData = array();
foreach($json as $key=>$id){
$newData []= (array)$id;
}
$newData []= array("id"=>(int)$deleteId);


$fill_view = json_encode($newData);
file_put_contents('delete-news.json', ($fill_view));
echo $fill_view;
} else {
echo json_encode(array());
}
exit();

?>

The best solution was to install denver and use PHP code on server-side. 
This is code in the js file.  
  deleteNewsItem: function(newsId, callback, scope) {
     var dataPath = this.dataPath;
      $.getJSON(dataPath + '/delete-news.php?id='+newsId, function(rawHeadlines) { 
         var headlines = [];
         $.each(rawHeadlines, function(index, rawHeadline) {
            headlines.push(rawHeadline.id);
        } 
     });
             if (callback) {
             callback.call(scope, headlines);
     }
     };
 
This is the code in the "delete_news.php" file. 
<?php

$deleteId = isset($_GET['id'])?$_GET['id']:false;
   if ($deleteId){
     $content = file_get_contents('delete-news.json');
     $json = json_decode($content);

$newData = array();
foreach($json as $key=>$id){
$newData []= (array)$id;
}
$newData []= array("id"=>(int)$deleteId);


$fill_view = json_encode($newData);
file_put_contents('delete-news.json', ($fill_view));
echo $fill_view;
} else {
echo json_encode(array());
}
exit();

?>

何时ThreadLocal优先于局部变量？(When is ThreadLocal preferred over Local Variables?)

最满意答案

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