php导出csv文件方法封装

/**
 * 导出csv文件
 * @param  string $filename 导出文件名
 * @param  array  $field    第一行header
 * @param  array  $map      字段映射,array('title'=>function($v){})
 * @param  array  $list     导出数据
 * @return [type]           [description]
 */
function exportCsv($filename, $field, $map, $list)
{
	header('Content-Disposition: attachment;filename='.$filename);
    header('Content-Type: application/vnd.ms-excel');
    header('Cache-Control: max-age=0');
    header("Accept-Ranges:bytes");

    $out = fopen('php://output', 'w');
    fputcsv($out, $field);

    $limit = 5000;
    $num=0;
	foreach($list as $k=>$v){
		// 每隔一段数据清除输出缓存
		if($k == $limit){
            ob_flush();
            $num=0;
        }
        $num+=1;

		$tmp = array();
		foreach($map as $k1=>$v1){
			if(isset($v[$k1]) && (is_callable($map[$k1]) || $map[$k1] instanceof Closure)){
				$tmp[$k1] = $v1($v);
			}else{
				$tmp[$v1] = $v[$v1];
			}
		}
		array_unshift($tmp, $k+1);
		
		fputcsv($out, $tmp);
		// 每次写入后销毁变量
        unset($tmp, $list[$k]);
	}
	fclose($out);
	die();
}

// 实际使用
$filename = 'test.csv';
$field = array(
	'列头1',
	'列头2',
	'列头3'
);
$extra = '测试1';
$map = array(
	'title1' => function($v){
		return 'test1';
	},
	'title2',
	'title3' => function($v)use(&$extra){
		return $extra.'--'.$v['title1']
	}
);
$data = array(
	array(
		'title1' => '111',
		'title2' => '222',
		'title3' => '333',
	),
);
exportCsv($filename, $field, $map, $data);