Read and write of zip file

Zip File reading

ZipInputStream The basic usage of ：

First, create a ZipInputStream, It's usually an incoming FileInputStream As a data source , And then the loop calls getNextEntry(), When the return value is null when , Express zip End of stream reading .

One ZipEntry Represents a compressed file or directory , If it's a compressed file , We will use read() Method to read , When the return value is -1 when , End of read .

Code implementation

public class Main {
	public static void main(String[] args) {
		try (ZipInputStream in = new ZipInputStream(new FileInputStream("C:\\IO flow \\Test.zip"),Charset.forName("gbk"))) {
			ZipEntry entry = null;
			// Extract each sub file in the compressed file 
			while((entry = in.getNextEntry())!=null) {
                System.out.println(entry.getName());
                int data = -1;
                while((data = in.read())!= -1){
                    System.out.println(data);
                }
			}
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

So let's use ZipInputStream Input stream , Realize a decompression function by yourself

Function realization ： To a zip Unzip the file

Implementation steps ：1, Create the decompression directory , obtain zip The name of the document , according to zip File name , Extract the name of the compressed Directory , Create the decompression directory , Then create the directory .

                  2, Traverse and read Zip Each sub file in the file , Create a buffered output stream , take Zip The file bytes read in the file are written into the new file , It should be noted that ： Every time you create an output stream , We all need to turn it off manually , When fewer file bytes are written , There will be buffer bytes that cannot be written normally .

public class Main {
	public static void main(String[] args) {
		// To decompress zip file 
		File zipFile = new File("C:\\IO flow \\Test.zip");
		
		//1. Create the decompression directory 
		// obtain zip The name of the document 
		String zipFileName = zipFile.getName();
		
		// according to zip File name , Extract the name of the compressed Directory 
		String targetFileName = zipFileName.substring(0,zipFileName.indexOf("."));
		
		// Create the decompression directory 
		File targetDir = new File(zipFile.getParent() + "\\" + targetFileName);
		
		if(!targetDir.exists()) {
			targetDir.mkdir();// Create directory 
		}
		
		//2. Parse read zip file 
		try (
		 ZipInputStream in = new ZipInputStream(new FileInputStream(zipFile),Charset.forName("gbk"))) {
			// Traverse Zip Each sub file in the file 
			ZipEntry zipEntry = null;
			while((zipEntry = in.getNextEntry())!=null) {
				// obtain zip The name of the sub file in the compressed package 
				String zipEntryFileName = zipEntry.getName();
                // Create the output stream of this file 
				String zipFilePath = targetDir.getPath() + "\\" + zipEntryFileName;
				// The output stream is defined in try() block , End automatic buffer emptying and close 
				try(BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(zipFilePath))){ ;
					//  Read the byte contents of the sub file 
					byte[] buff = new byte[1024];
					int len = -1;
					while ((len = in.read(buff)) != -1) {
                        bos.write(buff, 0, len);
					}
				 }
			   }
        } catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}
}

Zip Writing files

            ZipOutputStream It's a kind of FilterOutputStream, It can write content directly to zip package . We need to create one first ZipOutputStream, Usually a package FileOutStream, then , Before writing a file , First call putNextEntry( ), And then use write() write in byte[ ] data , Call after completion closeEntry( ), End the packaging of this file .

Let's take advantage of ZipOutputStream The output stream implements the specified function ： Write the specified file zip file

Function realization ： Compress a file directory .

Implementation steps ：1, Get and traverse the list of sub files in the original directory .

                  2, The byte contents of the original file , write in zip Compressed package .

We're doing zip When the file is written , It should be noted that the zip The compressed package should be under the same parent directory as the original directory .

public class Main {
	public static void main(String[] args) {
		// Original directory 
		File rootDir = new File("C:\\IO flow \\Test");
		
		// The files in the original directory , write in zip Compressed files 
		try ( ZipOutputStream out = new ZipOutputStream(new FileOutputStream(rootDir.getParent()+"\\"+rootDir.getName()+".zip"))) {
			// Get and traverse the list of sub files in the original directory 
			File[] files = rootDir.listFiles();
			for (File file : files) {
				// Create a ZipEntry
				out.putNextEntry(new ZipEntry(file.getName()));
				
				// The byte contents of the original file , write in zip Compressed package 
				out.write(Files.readAllBytes(file.toPath()));
				
				// End the present ZipEntry
				out.closeEntry();
			}
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}