在PHPExcel论坛上已经有很多关于PHPExcel的内存使用的文章。因此通读之前的一些讨论可能会给您一些想法。PHPExcel保留电子表格的“内存中”表示形式，并且容易受到PHP内存限制的影响。

该文件的物理大小在很大程度上无关紧要……了解该文件包含多少个单元格（每个工作表上的行*列）更为重要。

我一直使用的“经验法则”平均约为每单元1k，因此5M单元工作簿将需要5GB内存。但是，可以通过多种方法来减少该需求。可以将它们组合在一起，具体取决于您需要在工作簿中访问哪些信息以及您要如何处理。

如果您有多个工作表，但是不需要全部加载，则可以使用setLoadSheetsOnly（）方法来限制Reader将加载的工作表。加载单个命名工作表：

$inputFileType = 'Excel5'; 
$inputFileName = './sampleData/example1.xls';
$sheetname = 'Data Sheet #2'; 
/**  Create a new Reader of the type defined in $inputFileType  **/
$objReader = PHPExcel_IOFactory::createReader($inputFileType);
/**  Advise the Reader of which WorkSheets we want to load  **/ 
$objReader->setLoadSheetsOnly($sheetname); 
/**  Load $inputFileName to a PHPExcel Object  **/
$objPHPExcel = $objReader->load($inputFileName);

或者，您可以通过传递名称数组来一次调用setLoadSheetsOnly（）来指定多个工作表：

$inputFileType = 'Excel5'; 
$inputFileName = './sampleData/example1.xls';
$sheetnames = array('Data Sheet #1','Data Sheet #3'); 
/** Create a new Reader of the type defined in $inputFileType **/ 
$objReader = PHPExcel_IOFactory::createReader($inputFileType);
/** Advise the Reader of which WorkSheets we want to load **/ 
$objReader->setLoadSheetsOnly($sheetnames); 
/**  Load $inputFileName to a PHPExcel Object  **/
$objPHPExcel = $objReader->load($inputFileName);

如果您只需要访问工作表的一部分，则可以定义一个“读取过滤器”来识别您实际要加载的单元格：

$inputFileType = 'Excel5'; 
$inputFileName = './sampleData/example1.xls';
$sheetname = 'Data Sheet #3';

/**  Define a Read Filter class implementing PHPExcel_Reader_IReadFilter  */ 
class MyReadFilter implements PHPExcel_Reader_IReadFilter {
    public function readCell($column, $row, $worksheetName = '') {
        //  Read rows 1 to 7 and columns A to E only 
        if ($row >= 1 && $row <= 7) {
           if (in_array($column,range('A','E'))) { 
              return true;
           }
        } 
        return false;
    }
}

/**  Create an Instance of our Read Filter  **/ 
$filterSubset = new MyReadFilter(); 
/** Create a new Reader of the type defined in $inputFileType **/ 
$objReader = PHPExcel_IOFactory::createReader($inputFileType);
/**  Advise the Reader of which WorkSheets we want to load 
     It's more efficient to limit sheet loading in this manner rather than coding it into a Read Filter  **/ 
$objReader->setLoadSheetsOnly($sheetname); 
echo 'Loading Sheet using filter';
/**  Tell the Reader that we want to use the Read Filter that we've Instantiated  **/ 
$objReader->setReadFilter($filterSubset); 
/**  Load only the rows and columns that match our filter from $inputFileName to a PHPExcel Object  **/
$objPHPExcel = $objReader->load($inputFileName);

使用读取过滤器，您还可以“大块”地读取工作簿，以便在任何时候仅一个块驻留在内存中：

$inputFileType = 'Excel5'; 
$inputFileName = './sampleData/example2.xls';

/**  Define a Read Filter class implementing PHPExcel_Reader_IReadFilter  */ 
class chunkReadFilter implements PHPExcel_Reader_IReadFilter {
    private $_startRow = 0;
    private $_endRow = 0;

    /**  Set the list of rows that we want to read  */ 
    public function setRows($startRow, $chunkSize) { 
        $this->_startRow    = $startRow; 
        $this->_endRow      = $startRow + $chunkSize;
    }

    public function readCell($column, $row, $worksheetName = '') {
        //  Only read the heading row, and the rows that are configured in $this->_startRow and $this->_endRow 
        if (($row == 1) || ($row >= $this->_startRow && $row < $this->_endRow)) { 
           return true;
        }
        return false;
    } 
}

/**  Create a new Reader of the type defined in $inputFileType  **/
$objReader = PHPExcel_IOFactory::createReader($inputFileType);
/**  Define how many rows we want to read for each "chunk"  **/ 
$chunkSize = 20;
/**  Create a new Instance of our Read Filter  **/ 
$chunkFilter = new chunkReadFilter(); 
/**  Tell the Reader that we want to use the Read Filter that we've Instantiated  **/ 
$objReader->setReadFilter($chunkFilter);

/**  Loop to read our worksheet in "chunk size" blocks  **/ 
/**  $startRow is set to 2 initially because we always read the headings in row #1  **/
for ($startRow = 2; $startRow <= 65536; $startRow += $chunkSize) { 
    /**  Tell the Read Filter, the limits on which rows we want to read this iteration  **/ 
    $chunkFilter->setRows($startRow,$chunkSize); 
    /**  Load only the rows that match our filter from $inputFileName to a PHPExcel Object  **/ 
    $objPHPExcel = $objReader->load($inputFileName); 
    //    Do some processing here

    //    Free up some of the memory 
    $objPHPExcel->disconnectWorksheets(); 
    unset($objPHPExcel); 
}

如果您不需要加载格式信息，而仅加载工作表数据，则setReadDataOnly（）方法将告诉读者仅加载单元格值，而忽略任何单元格格式：

$inputFileType = 'Excel5';
$inputFileName = './sampleData/example1.xls';
/** Create a new Reader of the type defined in $inputFileType **/ 
$objReader = PHPExcel_IOFactory::createReader($inputFileType);
/** Advise the Reader that we only want to load cell data, not formatting **/ 
$objReader->setReadDataOnly(true);
/**  Load $inputFileName to a PHPExcel Object  **/
$objPHPExcel = $objReader->load($inputFileName);

使用单元缓存。这是一种减少每个单元所需的PHP内存的方法，但是会降低速度。它通过以压缩格式存储单元对象或在PHP内存（例如磁盘，APC，内存缓存）之外存储单元对象而工作…但是，保存的内存越多，脚本执行的速度就越慢。但是，您可以将每个单元所需的内存减少到大约300bytes，因此假设的5M单元将需要大约1.4GB的PHP内存。

单元缓存在开发人员文档的4.2.1节中进行了描述