带你掌握PHP中常见的文件操作

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这篇文章主要为大家详细介绍了PHP中常见的文件操作的相关知识,文字的示例代码讲解详细,具有一定的借鉴价值,
目录

    一、文件读取的5种方法
    二、文件写入
    三、文件复制、删除、重命名

一、文件读取的5种方法

1、file_get_contents: 将整个文件读入一个字符串

    file_get_contents(
    string $filename,
    bool $use_include_path = false,
    ?resource $context = null,
    int $offset = 0,
    ?int $length = null
    ): string|false

可以读取本地的文件

也可以用来打开一个网络地址实现简单的网页抓取

可以模拟post请求（stream_context_create）

        
$fileName = 'test.txt';
if (file_exists($fileName)) {
    $str = file_get_contents($fileName);
    echo $str;
} else {
    print_r("文件不存在");
}

2、file: 把整个文件读入一个数组中

    file(string $filename, int $flags = 0, ?resource $context = null): array|false

数组的每个元素对应于文件中的一行

可以读取本地的文件

也可以用来读取一个网络文件

        
$lines = file('test.txt');
foreach ($lines as $line_num => $line) {
    echo "Line #<b>{$line_num}</b> : " . htmlspecialchars($line) . "<br />\n";
}

3、file_open、file_gets、file_read、fclose: 从文件指针资源读取

3.1 fgets — 从文件指针中读取一行

    fgets(resource $stream, ?int $length = null): string|false

从文件中读取一行并返回长度最多为 length - 1 字节的字符串。碰到换行符（包括在返回值中）、EOF 或者已经读取了 length - 1 字节后停止（看先碰到那一种情况）。如果没有指定 length，则默认为 1K，或者说 1024 字节。
        
$fp = fopen("test.txt", "r");
if ($fp) {
    while (!feof($fp)) {
        $line = fgets($fp);
        echo $line . "<br />\n";
    }
    fclose($fp);
}

3.2 fread — 从文件指针中读取固定长度(可安全用于二进制文件）

    fread(resource $stream, int $length): string|false

        
$fp = fopen("test.txt", "r");
if ($fp) {
    $content = "";
    while (!feof($fp)) {
        $content .= fread($fp, 1024);
    }
    #$contents = fread($handle, filesize($filename));
    echo $content;
    fclose($fp);
}

4、SplFileObject 类

1. class SplFileObject extends SplFileInfo implements RecursiveIterator, SeekableIterator {
   
2. /* 常量 */
   
3. public const int DROP_NEW_LINE;
   
4. public const int READ_AHEAD;
   
5. public const int SKIP_EMPTY;
   
6. public const int READ_CSV;
   
7. /* 方法 */
   
8. public __construct(
   
9.     string $filename,
   
10.     string $mode = "r",
    
11.     bool $useIncludePath = false,
    
12.     ?resource $context = null
    
13. )
    
14. public current(): string|array|false
    
15. public eof(): bool
    
16. public fflush(): bool
    
17. public fgetc(): string|false
    
18. public fgetcsv(string $separator = ",", string $enclosure = """, string $escape = "\"): array|false
    
19. public fgets(): string
    
20. public fgetss(string $allowable_tags = ?): string
    
21. public flock(int $operation, int &$wouldBlock = null): bool
    
22. public fpassthru(): int
    
23. public fputcsv(
    
24.     array $fields,
    
25.     string $separator = ",",
    
26.     string $enclosure = """,
    
27.     string $escape = "\",
    
28.     string $eol = "\n"
    
29. ): int|false
    
30. public fread(int $length): string|false
    
31. public fscanf(string $format, mixed &...$vars): array|int|null
    
32. public fseek(int $offset, int $whence = SEEK_SET): int
    
33. public fstat(): array
    
34. public ftell(): int|false
    
35. public ftruncate(int $size): bool
    
36. public fwrite(string $data, int $length = 0): int|false
    
37. public getChildren(): null
    
38. public getCsvControl(): array
    
39. public getFlags(): int
    
40. public getMaxLineLen(): int
    
41. public hasChildren(): false
    
42. public key(): int
    
43. public next(): void
    
44. public rewind(): void
    
45. public seek(int $line): void
    
46. public setCsvControl(string $separator = ",", string $enclosure = """, string $escape = "\"): void
    
47. public setFlags(int $flags): void
    
48. public setMaxLineLen(int $maxLength): void
    
49. public __toString(): string
    
50. public valid(): bool
    
51. /* 继承的方法 */
    
52. public SplFileInfo::getATime(): int|false
    
53. public SplFileInfo::getBasename(string $suffix = ""): string
    
54. public SplFileInfo::getCTime(): int|false
    
55. public SplFileInfo::getExtension(): string
    
56. public SplFileInfo::getFileInfo(?string $class = null): SplFileInfo
    
57. public SplFileInfo::getFilename(): string
    
58. public SplFileInfo::getGroup(): int|false
    
59. public SplFileInfo::getInode(): int|false
    
60. public SplFileInfo::getLinkTarget(): string|false
    
61. public SplFileInfo::getMTime(): int|false
    
62. public SplFileInfo::getOwner(): int|false
    
63. public SplFileInfo::getPath(): string
    
64. public SplFileInfo::getPathInfo(?string $class = null): ?SplFileInfo
    
65. public SplFileInfo::getPathname(): string
    
66. public SplFileInfo::getPerms(): int|false
    
67. public SplFileInfo::getRealPath(): string|false
    
68. public SplFileInfo::getSize(): int|false
    
69. public SplFileInfo::getType(): string|false
    
70. public SplFileInfo::isDir(): bool
    
71. public SplFileInfo::isExecutable(): bool
    
72. public SplFileInfo::isFile(): bool
    
73. public SplFileInfo::isLink(): bool
    
74. public SplFileInfo::isReadable(): bool
    
75. public SplFileInfo::isWritable(): bool
    
76. public SplFileInfo::openFile(string $mode = "r", bool $useIncludePath = false, ?resource $context = null): SplFileObject
    
77. public SplFileInfo::setFileClass(string $class = SplFileObject::class): void
    
78. public SplFileInfo::setInfoClass(string $class = SplFileInfo::class): void
    
79. public SplFileInfo::__toString(): string
    
80. }
    
81. 预定义常量
    
82. 
    
83. SplFileObject::DROP_NEW_LINE
    
84. 
    
85.     删除行尾的换行符。
    
86. SplFileObject::READ_AHEAD
    
87. 
    
88.     使用 rewind 或 next 方法时，从文件中读取一行数据。
    
89. SplFileObject::SKIP_EMPTY
    
90. 
    
91.     跳过文件中的空白行。这需要启用 READ_AHEAD 标志，以达到预期的效果。
    
92. SplFileObject::READ_CSV
    
93. 
    
94.     以 CSV 行的形式读取。
    
95. 
    
96. 目录
    
97. 
    
98.     SplFileObject::__construct — Construct a new file object
    
99.     SplFileObject::current — Retrieve current line of file
    
100.     SplFileObject::eof — Reached end of file
     
101.     SplFileObject::fflush — Flushes the output to the file
     
102.     SplFileObject::fgetc — Gets character from file
     
103.     SplFileObject::fgetcsv — Gets line from file and parse as CSV fields
     
104.     SplFileObject::fgets — Gets line from file
     
105.     SplFileObject::fgetss — Gets line from file and strip HTML tags
     
106.     SplFileObject::flock — Portable file locking
     
107.     SplFileObject::fpassthru — Output all remaining data on a file pointer
     
108.     SplFileObject::fputcsv — Write a field array as a CSV line
     
109.     SplFileObject::fread — Read from file
     
110.     SplFileObject::fscanf — Parses input from file according to a format
     
111.     SplFileObject::fseek — Seek to a position
     
112.     SplFileObject::fstat — Gets information about the file
     
113.     SplFileObject::ftell — Return current file position
     
114.     SplFileObject::ftruncate — Truncates the file to a given length
     
115.     SplFileObject::fwrite — Write to file
     
116.     SplFileObject::getChildren — No purpose
     
117.     SplFileObject::getCsvControl — Get the delimiter, enclosure and escape character for CSV
     
118.     SplFileObject::getCurrentLine — 别名 SplFileObject::fgets
     
119.     SplFileObject::getFlags — Gets flags for the SplFileObject
     
120.     SplFileObject::getMaxLineLen — Get maximum line length
     
121.     SplFileObject::hasChildren — SplFileObject does not have children
     
122.     SplFileObject::key — Get line number
     
123.     SplFileObject::next — Read next line
     
124.     SplFileObject::rewind — Rewind the file to the first line
     
125.     SplFileObject::seek — Seek to specified line
     
126.     SplFileObject::setCsvControl — Set the delimiter, enclosure and escape character for CSV
     
127.     SplFileObject::setFlags — Sets flags for the SplFileObject
     
128.     SplFileObject::setMaxLineLen — Set maximum line length
     
129.     SplFileObject::__toString — Returns the current line as a string
     
130.     SplFileObject::valid — Not at EOF
     
131. 
     
132. ＋add a note
     
133. User Contributed Notes 4 notes
     
134. up
     
135. down
     
136. 86
     
137. Lars Gyrup Brink Nielsen ¶
     
138. 10 years ago
     
139. Note that this class has a private (and thus, not documented) property that holds the file pointer. Combine this with the fact that there is no method to close the file handle, and you get into situations where you are not able to delete the file with unlink(), etc., because an SplFileObject still has a handle open.
     
140. 
     
141. To get around this issue, delete the SplFileObject like this:
     
142. 
     
143. ---------------------------------------------------------------------
     
144. <?php
     
145. print "Declaring file object\n";
     
146. $file = new SplFileObject('example.txt');
     
147. 
     
148. print "Trying to delete file...\n";
     
149. unlink('example.txt');
     
150. 
     
151. print "Closing file object\n";
     
152. $file = null;
     
153. 
     
154. print "Deleting file...\n";
     
155. unlink('example.txt');
     
156. 
     
157. print 'File deleted!';
     
158. ?>
     
159. 
     

复制代码

5、调用linux命令

处理超大文件，比如日志文件时，可以用fseek函数定位，也可以调用linux命令处理

        
$file = 'access.log';
$file = escapeshellarg($file); // 对命令行参数进行安全转义
$line = `tail -n 1 $file`;
echo $line;

二、文件写入

1、file_put_contents: 将数据写入文件

    file_put_contents(
    string $filename,
    mixed $data,
    int $flags = 0,
    ?resource $context = null
    ): int|false

        
$content = "Hello, world!"; // 要写入文件的内容
$file = "test.txt"; // 文件路径

file_put_contents($file, $content);

2、fwrite： 写入文件（可安全用于二进制文件）

    fwrite(resource $stream, string $data, ?int $length = null): int|false

        
$content = "这是要写入文件的内容";
$file = fopen("test.txt", "w"); // 打开文件写入模式
if ($file) {
    fwrite($file, $content); // 将内容写入文件
    fclose($file); // 关闭文件
}

3、SplFileObject 类

三、文件复制、删除、重命名

1、copy: 拷贝文件

    copy(string $from, string $to, ?resource $context = null): bool

        
$file = 'test.txt';
$newFile = 'test2.txt';

if (!copy($file, $newFile)) {
    echo "failed to copy $file...\n";
}

2、unlink: 删除文件

    unlink(string $filename, ?resource $context = null): bool

        
$fileName = 'test2.txt';
if (file_exists($fileName)) {
   if (unlink($fileName)) {
       echo '删除成功';
   }
}

3、rename: 重命名文件

    rename(string $from, string $to, ?resource $context = null): bool

可以在不同目录间移动

如果重命名文件时 to 已经存在，将会覆盖掉它

如果重命名文件夹时 to 已经存在，本函数将导致一个警告

        
$fileName = 'test.txt';
$rename = 'test_new.txt';
if (file_exists($fileName)) {
   if (rename($fileName, $rename )) {
       echo '重命名成功';
   }
}

到此。