File compression and decompression methods and solutions to common problems in PHP

With the advent of the big data era, the amount of data is increasing, and more efficient ways are needed to transmit and store data. File compression and decompression have become one of the very important technologies, and the PHP language also provides corresponding APIs to achieve file compression and decompression.

1. File compression method

In PHP, you can use the ZipArchive class to create and operate compressed files in ZIP format. The ZipArchive class provides the following methods to create and operate compressed files:

1. Creating ZIP compressed files

The ZipArchive::open() method is used to open a ZIP file, the parameters are file name and operation type, which can be ZipArchive::CREATE (create a new file) or ZipArchive::OVERWRITE (overwrite an existing file).

The sample code is as follows:

$zip = new ZipArchive();
if ($zip->open('test.zip', ZipArchive::CREATE) === TRUE) {
    // 添加文件到压缩包
    $zip->addFile('file1.txt');
    $zip->addFile('file2.txt');
    // 关闭压缩包
    $zip->close();
}

2. Add files to ZIP compressed files

The ZipArchive::addFile() method is used to add files to the opened ZIP file Add a file.

The sample code is as follows:

$zip = new ZipArchive();
if ($zip->open('test.zip', ZipArchive::CREATE) === TRUE) {
    $zip->addFile('file1.txt');
    $zip->addFile('file2.txt');
    $zip->close();
}

3. Add a directory to a ZIP compressed file

The ZipArchive::addEmptyDir() method is used to add a directory to an open ZIP file Add a directory.

The sample code is as follows:

$zip = new ZipArchive();
if ($zip->open('test.zip', ZipArchive::CREATE) === TRUE) {
    $zip->addEmptyDir('dir1');
    $zip->addFile('dir1/file1.txt');
    $zip->addFile('dir1/file2.txt');
    $zip->addEmptyDir('dir2');
    $zip->close();
}

4. Add the data in memory to the ZIP compressed file

The ZipArchive::addFromString() method is used to add data to the opened ZIP archive. ZIP file adds in-memory data.

The sample code is as follows:

$zip = new ZipArchive();
if ($zip->open('test.zip', ZipArchive::CREATE) === TRUE) {
    $zip->addFromString('file1.txt', 'this is a test file1');
    $zip->addFromString('file2.txt', 'this is a test file2');
    $zip->close();
}

2. File decompression method

In PHP, you can use the ZipArchive class to decompress compressed files in ZIP format. The ZipArchive class provides the following methods to decompress ZIP files:

1. Open ZIP file

The ZipArchive::open() method is used to open a ZIP file , the parameters are file name and operation type, which can be ZipArchive::CREATE (create a new file) or ZipArchive::OVERWRITE (overwrite an existing file).

The sample code is as follows:

$zip = new ZipArchive();
if ($zip->open('test.zip') === TRUE) {
    // 解压到指定目录
    $zip->extractTo('./unzip');
    // 关闭ZIP文件
    $zip->close();
}

2. Extract the ZIP file to the specified directory

The ZipArchive::extractTo() method is used to extract the ZIP file to the specified directory Directory.

The sample code is as follows:

$zip = new ZipArchive();
if ($zip->open('test.zip') === TRUE) {
    $zip->extractTo('./unzip');
    $zip->close();
}

3. Decompress the specified file in the ZIP file

The ZipArchive::getStream() method is used to obtain the specified file in the ZIP file The data stream of the file can be used to decompress the specified file in the ZIP file.

The sample code is as follows:

$zip = new ZipArchive();
if ($zip->open('test.zip') === TRUE) {
    // 获取file1.txt的数据流
    $stream = $zip->getStream('file1.txt');
    // 读取数据流
    $data = '';
    while (!feof($stream)) {
        $data .= fread($stream, 1024);
    }
    fclose($stream);
    // 写入解压后的文件
    file_put_contents('./unzip/file1.txt', $data);
    $zip->close();
}

3. Solutions to common problems

1. Decompress Chinese file names with garbled characters

In Windows systems When using the ZipArchive class to decompress a ZIP file with a Chinese file name, the Chinese file name may be garbled. The solution is to encode the ZIP file name to GBK format in Windows systems.

The sample code is as follows:

// 修改ZIP文件名编码
$zipFilename = iconv('UTF-8', 'GBK', 'test.zip');
// 打开ZIP文件
$zip = new ZipArchive();
if ($zip->open($zipFilename) === TRUE) {
    // 解压ZIP文件
    $zip->extractTo('./unzip');
    // 关闭ZIP文件
    $zip->close();
}

2. The empty directory in the compressed file list is lost

When adding an empty directory to a ZIP compressed file, if the empty directory If the parent directory does not exist, the empty directory will be ignored. The solution is to add the parent directory of the empty directory before adding it.

The sample code is as follows:

$zip = new ZipArchive();
if ($zip->open('test.zip', ZipArchive::CREATE) === TRUE) {
    $zip->addEmptyDir('dir1');
    $zip->addFile('dir1/file1.txt');
    $zip->addFile('dir1/file2.txt');
    // 先添加空目录的父目录
    $zip->addEmptyDir('dir2');
    $zip->addEmptyDir('dir2/dir3');
    $zip->addFile('dir2/dir3/file3.txt');
    $zip->close();
}

3. ZIP file decompression failure

When decompressing a ZIP file, decompression may fail. The solution is to check whether the ZIP file is correct. You can use the system's own decompression tool or other third-party tools to verify the integrity of the ZIP file.

In addition, if the ZIP file contains viruses or Trojans, it may also cause decompression failure. You can use anti-virus software to scan ZIP files to ensure the security of ZIP files.

The above is an introduction to file compression and decompression methods and solutions to common problems in PHP. I believe that by learning this knowledge, you can better deal with issues related to file compression and decompression.

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