可参考

我这里是从项目代码里总出来的：

1、首先在application/core文件夹下增加MY_Loader.php文件。只要增加这个类就可以，其他操作不变，在视图文件中就可以使用视图继承了。

文件内容如下：

1 
     _stacks[$this->_current]['extends'] = $tplname; 41     } 42  43     /** 44      * 开始定义一个区块 45      * 46      * @param string $block_name 47      * @param mixed $config 48      * 49      * @access protected 50      */ 51     protected function _block($block_name, $config = null) 52     { 53         $stack =& $this->_stacks[$this->_current]; 54         if (!empty($stack['blocks_stacks'])) 55         { 56             // 如果存在嵌套的 block，则需要记录下嵌套的关系 57             $last = $stack['blocks_stacks'][count($stack['blocks_stacks']) - 1]; 58             $stack['nested_blocks'][] = array($block_name, $last); 59         } 60         $this->_stacks[$this->_current]['blocks_config'][$block_name] = $config; 61         array_push($stack['blocks_stacks'], $block_name); 62         ob_start(); 63     } 64  65     /** 66      * 结束一个区块 67      * 68      * @access protected 69      */ 70     protected function _endblock() 71     { 72         $block_name = array_pop($this->_stacks[$this->_current]['blocks_stacks']); 73         $this->_stacks[$this->_current]['blocks'][$block_name] = ob_get_clean(); 74         echo "%block_{
   $block_name}_{
   $this->_stacks[$this->_current]['id']}%"; 75     } 76  77  78     /** 79      * 载入一个视图片段 80      * 81      * @param string $element_name 视图名称 82      * @param array $vars 83      * 84      * @access protected 85      */ 86     protected function _element($element_name, array $vars = null) 87     { 88         $file_exists = FALSE; 89         $filename = ''; 90         foreach ($this->_ci_view_paths as $view_file => $cascade) 91         { 92             $filename = $view_file.$element_name.EXT; 93             if ( ! file_exists($filename)) 94             { 95                 $file_exists = FALSE; 96             }else{ 97                 $file_exists = TRUE;break; 98             } 99         }100         if(!$file_exists){101             show_error('Unable to load the requested file: '.$filename);102         }else{103             extract($this->_ci_cached_vars);104             if (is_array($vars)) extract($vars);105             include($filename);106         }107     }108 109     /**110      * Loader111      *112      * 这个函数用来加载视图或者文件.113      * 这个函数改写 CI_Loader 类内函数，使其支持视图继承和多重继承。114      *115      * @access    private116      * @param    array117      * @return    void118      */119     function _ci_load($_ci_data)120     {121         // 设置默认的数据变量122         foreach (array('_ci_view', '_ci_vars', '_ci_path', '_ci_return', '_ci_viewid', '_ci_stack') as $_ci_val)123         {124             $$_ci_val = ( ! isset($_ci_data[$_ci_val])) ? FALSE : $_ci_data[$_ci_val];125         }126 127         // 设置请求文件的路径128         if ($_ci_path != '')129         {130             $_ci_x = explode('/', $_ci_path);131             $_ci_file = end($_ci_x);132         }133         else134         {135             $_ci_ext = pathinfo($_ci_view, PATHINFO_EXTENSION);136             $_ci_file = ($_ci_ext == '') ? $_ci_view.'.php' : $_ci_view;137 138             foreach ($this->_ci_view_paths as $view_file => $cascade)139             {140                 if (file_exists($view_file.$_ci_file))141                 {142                     $_ci_path = $view_file.$_ci_file;143                     $file_exists = TRUE;144                     break;145                 }146 147                 if ( ! $cascade)148                 {149                     break;150                 }151             }152         }153 154         if ( ! file_exists($_ci_path))155         {156             show_error('Unable to load the requested file: '.$_ci_file);157         }158 159         // 这允许任何加载使用 $this->load (views, files, etc.)160         // 成为从内部控制器和模型函数访问.161 162         $_ci_CI =& get_instance();163         foreach (get_object_vars($_ci_CI) as $_ci_key => $_ci_var)164         {165             if ( ! isset($this->$_ci_key))166             {167                 $this->$_ci_key =& $_ci_CI->$_ci_key;168             }169         }170 171         /*172          * 提取缓存和变量   也就是把数组下标变成变量173          *174          * You can either set variables using the dedicated $this->load_vars()175          * function or via the second parameter of this function. We'll merge176          * the two types and cache them so that views that are embedded within177          * other views can have access to these variables.178          */179         if (is_array($_ci_vars))180         {181             $this->_ci_cached_vars = array_merge($this->_ci_cached_vars, $_ci_vars);182         }183         extract($this->_ci_cached_vars);184 185         //-----by:kth007 20100422------------------------------------------------------------------------------186         if ( ! $_ci_viewid) $_ci_viewid = mt_rand();187 188         $stack = array(189         'id'            => $_ci_viewid,190         'contents'      => '',191         'extends'       => '',192         'blocks_stacks' => array(),193         'blocks'        => array(),194         'blocks_config' => array(),195         'nested_blocks' => array(),196         );197         array_push($this->_stacks, $stack);198         $this->_current = count($this->_stacks) - 1;199         unset($stack);200         //-----------------------------------------------------------------------------------201 202         /*203          * 缓冲输出204          *205          * We buffer the output for two reasons:206          * 1. Speed. You get a significant speed boost.207          * 2. So that the final rendered template can be208          * post-processed by the output class.  Why do we209          * need post processing?  For one thing, in order to210          * show the elapsed page load time.  Unless we211          * can intercept the content right before it's sent to212          * the browser and then stop the timer it won't be accurate.213          */214         ob_start();215 216         // If the PHP installation does not support short tags we'll217         // do a little string replacement, changing the short tags218         // to standard PHP echo statements.219 220         if ((bool) @ini_get('short_open_tag') === FALSE AND config_item('rewrite_short_tags') == TRUE)221         {222             echo eval('?>'.preg_replace("/;*\s*\?>/", "; ?>", str_replace('
     _stacks[$this->_current];234         $stack['contents'] = ob_get_clean();235 236         // 如果有继承视图，则用继承视图中定义的块内容替换当前视图的块内容237         if (is_array($_ci_stack))238         {239             foreach ($_ci_stack['blocks'] as $block_name => $contents)240             {241                 if (isset($stack['blocks_config'][$block_name]))242                 {243                     switch (strtolower($stack['blocks_config'][$block_name]))244                     {245                         case 'append':246                             $stack['blocks'][$block_name] .= $contents;247                             break;248                         case 'replace':249                         default:250                             $stack['blocks'][$block_name] = $contents;251                     }252                 }253                 else254                 {255                     $stack['blocks'][$block_name] = $contents;256                 }257             }258         }259         // 如果有嵌套 block，则替换内容260         while (list($child, $parent) = array_pop($stack['nested_blocks']))261         {262             $stack['blocks'][$parent] = str_replace("%block_{
   $child}_{
   $_ci_viewid}%",263             $stack['blocks'][$child], $stack['blocks'][$parent]);264             unset($stack['blocks'][$child]);265         }266         // 保存对当前视图堆栈的修改267         $this->_stacks[$this->_current] = $stack;268 269         if ($stack['extends'])270         {271             //私有继承.272             $filename = "{
   $stack['extends']}".EXT;273                 274             return $this->_ci_load(array(275                                 '_ci_view' => $filename, 276                                 //'_ci_vars' => $this->_ci_cached_vars,277                                 '_ci_return' => $_ci_return,278                                 '_ci_viewid'=>$_ci_viewid, 279                                 '_ci_stack'=>$this->_stacks[$this->_current],280             ));281         }282         else283         {284             // 最后一个视图一定是没有 extends 的285             $last = array_pop($this->_stacks);286             foreach ($last['blocks'] as $block_name => $contents)287             {288                 $last['contents'] = str_replace("%block_{
   $block_name}_{
   $last['id']}%",289                 $contents, $last['contents']);290             }291             $this->_stacks = array();292             293             294             if ($_ci_return === TRUE)295             {296                 @ob_end_clean();297                 return $last['contents'];298             }299 300             if (ob_get_level() > $this->_ci_ob_level + 1)301             {302                 ob_end_flush();303             }304             else305             {306                 $_ci_CI->output->append_output($last['contents']);307                 @ob_end_clean();308             }309 310         }311 //--------------------------------------------------------------------------------------------312 313         314         // Return the file data if requested315 /*        if ($_ci_return === TRUE)316         {317             $buffer = ob_get_contents();318             @ob_end_clean();319             return $buffer;320         }321 */322         /*323          * Flush the buffer... or buff the flusher?324          *325          * In order to permit views to be nested within326          * other views, we need to flush the content back out whenever327          * we are beyond the first level of output buffering so that328          * it can be seen and included properly by the first included329          * template and any subsequent ones. Oy!330          *331          */332 /*        if (ob_get_level() > $this->_ci_ob_level + 1)333         {334             ob_end_flush();335         }336         else337         {338             $_ci_CI->output->append_output(ob_get_contents());339             @ob_end_clean();340         }341 */342 343 344     }345 346 }347 348 /* End of file MY_Loader.php */349 /* Location: ./application/core/MY_Loader.php */

2、在视图文件中使用视图继承：

首先可以在视图中增加一些基础的视图文件作为父视图，以供继承使用，如:view/_layouts/default_layout.php

代码可参考如下：

1  2  3  4 
      5  6  7  8 
     _block('head'); ?>
     
     _endblock(); ?> 9 10 11 
     
      这里是头部
     
12 
     
      这里是导航
     
13 
     
      这里是左栏
     
14 
     
      15 
      load->_block('content'); ?>
      load->_endblock(); ?>
     
16 17 
     
      _block('footer')?> 这里是尾部 
      _endblick();?>
     
18 19 

然后在自已的视图里就可以继承这个视图了

如：

1         //继承父视图 2  
     _extends('_layouts/default_layout'); ?> 3  //　重写title 4  
     _block('title'); ?>我自己的title,覆盖父类的title
     _endblock(); ?> 5 　 6 //重写head部分，可以引入一些自己的JS和CSS， 7 
     _block('head'); ?>
     
     _endblock(); ?> 8  9  //覆盖父视图中的contents部分，这里就可以自定义自己的内容部分了10   
     _block('contents'); ?>11   12   
13   
     
      14   
      
       
       
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        18  
       
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20    如果您的浏览器没有自动跳转，请点击这里21  
       
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     24  27 
     28  29  
     _endblock(); ?>

还可以载入某个视图片段，方法如下：

     load->_element('topnews', $topnews);?>