Java对ZIP文件格式有直接支持。通常，我们将使用java.util.zip包中的以下四个类来处理ZIP文件格式：
- ZipEntry
- ZipInputStream
- ZipOutputStream
- ZipFile
ZipEntry对象表示ZIP文件格式的归档文件中的条目。
zip条目可以是压缩的或未压缩的。
ZipEntry类具有设置和获取有关ZIP文件中的条目的信息的方法。
ZipInputStream可以从每个条目的ZIP文件读取数据。
ZipOutputStream可以将数据写入每个条目的ZIP文件。
ZipFile是一个从ZIP文件读取条目的实用程序类。
以下代码显示如何创建ZIP文件
import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.util.zip.Deflater; import java.util.zip.ZipEntry; import java.util.zip.ZipOutputStream; public class Main { public static void main(String[] args) { String zipFileName = "ziptest.zip"; String[] entries = new String[2]; entries[0] = "test1.txt"; entries[1] = "notes" File.separator "test2.txt"; zip(zipFileName, entries); } public static void zip(String zipFileName, String[] zipEntries) { try (ZipOutputStream zos = new ZipOutputStream(new BufferedOutputStream( new FileOutputStream(zipFileName)))) { // Set the compression level to best compression zos.setLevel(Deflater.BEST_COMPRESSION); for (int i = 0; i < zipEntries.length; i ) { File entryFile = new File(zipEntries[i]); if (!entryFile.exists()) { System.out.println("The entry file " entryFile.getAbsolutePath() " does not exist"); System.out.println("Aborted processing."); return; } ZipEntry ze = new ZipEntry(zipEntries[i]); zos.putNextEntry(ze); addEntryContent(zos, zipEntries[i]); zos.closeEntry(); } } catch (IOException e) { e.printStackTrace(); } } public static void addEntryContent(ZipOutputStream zos, String entryFileName) throws IOException, FileNotFoundException { BufferedInputStream bis = new BufferedInputStream(new FileInputStream( entryFileName)); byte[] buffer = new byte[1024]; int count = -1; while ((count = bis.read(buffer)) != -1) { zos.write(buffer, 0, count); } bis.close(); } }
读取Zip文件
以下代码显示如何读取ZIP文件的内容。
import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.util.zip.ZipEntry; import java.util.zip.ZipInputStream; public class Main { public static void main(String[] args) { String zipFileName = "ziptest.zip"; String unzipdirectory = "extracted"; unzip(zipFileName, unzipdirectory); } public static void unzip(String zipFileName, String unzipdir) { try (ZipInputStream zis = new ZipInputStream(new BufferedInputStream( new FileInputStream(zipFileName)))) { ZipEntry entry = null; while ((entry = zis.getNextEntry()) != null) { // Extract teh entry"s contents extractEntryContent(zis, entry, unzipdir); } } catch (IOException e) { e.printStackTrace(); } } public static void extractEntryContent(ZipInputStream zis, ZipEntry entry, String unzipdir) throws IOException, FileNotFoundException { String entryFileName = entry.getName(); String entryPath = unzipdir File.separator entryFileName; createFile(entryPath); BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream( entryPath)); byte[] buffer = new byte[1024]; int count = -1; while ((count = zis.read(buffer)) != -1) { bos.write(buffer, 0, count); } bos.close(); } public static void createFile(String filePath) throws IOException { File file = new File(filePath); File parent = file.getParentFile(); if (!parent.exists()) { parent.mkdirs(); } file.createNewFile(); } }
例2
下面的代码显示了如何使用ZipFile类。
当你只想在ZIP文件中列出条目时，ZipFile类派上用场。
import java.io.InputStream; import java.util.Enumeration; import java.util.zip.ZipEntry; import java.util.zip.ZipFile; public class Main { public static void main(String[] args) throws Exception { ZipFile zf = new ZipFile("ziptest.zip"); // Get the enumeration for all zip entries and loop through them Enumeration<? extends ZipEntry> e = zf.entries(); ZipEntry entry = null; while (e.hasMoreElements()) { entry = e.nextElement(); // Get the input stream for the current zip entry InputStream is = zf.getInputStream(entry); /* Read data for the entry using the is object */ // Print the name of the entry System.out.println(entry.getName()); } } }
以下代码使用Stream类和lambda表达式重写上述代码。
import java.io.IOException; import java.io.InputStream; import java.util.stream.Stream; import java.util.zip.ZipEntry; import java.util.zip.ZipFile; public class Main { public static void main(String[] args) throws Exception { ZipFile zf = new ZipFile("ziptest.zip"); Stream<? extends ZipEntry> entryStream = zf.stream(); entryStream.forEach(entry -> { try { // Get the input stream for the current zip entry InputStream is = zf.getInputStream(entry); System.out.println(entry.getName()); } catch (IOException e) { e.printStackTrace(); } }); } }
GZIPInputStream和GZIPOutputStream类用于与GZIP文件格式配合使用。
