Java解压缩RAR文件

Java自带的解压缩库不支持RAR文件的解压缩，因此需要使用第三方库来实现。其中，比较常用的有两个库：junrar和SevenZipJBinding。

使用junrar库来解压缩RAR文件的示例代码如下：

1. 添加依赖

<dependency>
    <groupId>com.github.junrar</groupId>
    <artifactId>junrar</artifactId>
    <version>1.0.0</version>
</dependency>

2. 编写解压缩代码

import com.github.junrar.Archive;
import com.github.junrar.rarfile.FileHeader;

import java.io.File;
import java.io.FileOutputStream;

public class RarExtractor {

    public static void extract(String archivePath, String destinationPath) throws Exception {
        Archive archive = new Archive(new File(archivePath));
        FileHeader fileHeader = archive.nextFileHeader();
        while (fileHeader != null) {
            String fileName = fileHeader.getFileNameW().isEmpty() ? fileHeader.getFileNameString() : fileHeader.getFileNameW();
            String filePath = destinationPath + File.separator + fileName;
            if (fileHeader.isDirectory()) {
                new File(filePath).mkdirs();
            } else {
                FileOutputStream fos = new FileOutputStream(new File(filePath));
                archive.extractFile(fileHeader, fos);
                fos.close();
            }
            fileHeader = archive.nextFileHeader();
        }
        archive.close();
    }

    public static void main(String[] args) throws Exception {
        String archivePath = "/path/to/archive.rar";
        String destinationPath = "/path/to/destination";
        extract(archivePath, destinationPath);
    }
}

使用SevenZipJBinding库来解压缩RAR文件的示例代码如下：

1. 添加依赖

<dependency>
    <groupId>net.sf.sevenzipjbinding</groupId>
    <artifactId>sevenzipjbinding</artifactId>
    <version>9.20-2.00</version>
</dependency>

2. 编写解压缩代码

import net.sf.sevenzipjbinding.*;
import net.sf.sevenzipjbinding.impl.RandomAccessFileInStream;
import net.sf.sevenzipjbinding.simple.ISimpleInArchive;
import net.sf.sevenzipjbinding.simple.ISimpleInArchiveItem;

import java.io.File;
import java.io.FileOutputStream;

public class RarExtractor {

    public static void extract(String archivePath, String destinationPath) throws Exception {
        RandomAccessFileInStream inputStream = new RandomAccessFileInStream(new File(archivePath));
        IInArchive archive = SevenZip.openInArchive(null, inputStream);
        ISimpleInArchive simpleInArchive = archive.getSimpleInterface();

        for (ISimpleInArchiveItem item : simpleInArchive.getArchiveItems()) {
            String filePath = destinationPath + File.separator + item.getPath();
            if (item.isFolder()) {
                new File(filePath).mkdirs();
            } else {
                FileOutputStream fos = new FileOutputStream(new File(filePath));
                byte[] buffer = new byte[4096];
                item.extractSlow(new ISequentialOutStream() {
                    @Override
                    public int write(byte[] data) throws SevenZipException {
                        try {
                            fos.write(data);
                        } catch (Exception e) {
                            throw new SevenZipException(e);
                        }
                        return data.length;
                    }
                });
                fos.close();
            }
        }

        archive.close();
        inputStream.close();
    }

    public static void main(String[] args) throws Exception {
        String archivePath = "/path/to/archive.rar";
        String destinationPath = "/path/to/destination";
        extract(archivePath, destinationPath);
    }
}