Java对ZIP文件格式有直接支持。通过使用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()
}
}
上面的代码生成以下结果。
The entry file F:\website\yiibai\worksp\test1.txt does not exist
Aborted processing.
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&aposs 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()
}
}
实例-2
下面的代码显示了如何使用ZipFile类。当想在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类用于处理GZIP文件格式。