1. ZipEntry 是包括目录的,也就是目录也被当做是一个单独的Entry,在列出它下面的文件之前先列出这个directory entry.
这个在解压ZIP文件的的时候特别有用,我们要先创建这个目录，然后在解压目录下面的文件，否则解压的时候会说目录不存在.
ZipInputStream zis = new ZipInputStream(new FileInputStream("F:\workspace\HibernateSrc\lib\hibernate3.jar"));
ZipEntry entry = zis.getNextEntry();
2.JarEntry是不包括目录的,只包括class文件对应的entry, 要想访问目录，请使用ZipEntry读取Jar文件.
JarInputStream jis = new JarInputStream(new FileInputStream(mainJar));
JarEntry entry = jis.getNextJarEntry();
3. 往jar文件里写数据的时候，要首先调用jos.putNextEntry(entry);放入一个entry记录，然后调用jos.write(temp, 0, count);往对应的记录写数据.
4. 读entry内容的时候,先要穿件一个JarFile or ZipFile, 然后遍历所有的entry记录，可以直接调用zip.entires()来得到entry的所有记录，也可以对jar&zip文件
创建一个JarInputStream & ZipInputStream 来遍历entry记录, 当选定了entry后，调用JarFile.getInputStream(entry)来拿到对应entry记录的输入流.
下面的蓝色部分代码是读入的操作，红色部分代码是输出的操作
JarFile zipIn = new JarFile(mainJar); InputStream readin = null; JarOutputStream jos = new JarOutputStream(new FileOutputStream("rt.jar")); JarInputStream jis = new JarInputStream(new FileInputStream(mainJar)); JarEntry entry = jis.getNextJarEntry(); while(entry!=null) { String name = entry.getName(); //remove the .class suffix. name = name.substring(0,name.lastIndexOf(".")); if(depencyClass.contains(name)) { //put an entry record and write the binary data jos.putNextEntry(entry); readin = zipIn.getInputStream(entry); byte[] temp = new byte[4096]; int count = readin.read(temp); while (count != -1) { jos.write(temp, 0, count); count = readin.read(temp); } readin.close(); } entry = jis.getNextJarEntry(); } jis.close(); jos.close();
下面是两个例子
ReduceJRE是用来抽取Jar里面特定的class文件到一个新的rt.jar
public class ReduceJRE {
public static void main(String[] args) throws Exception {
String mainJar = null;
String classDenpdencyFile = null;
if(args!=null && args.length==2)
{
mainJar = args[0];
classDenpdencyFile = args[1];
}
else {
mainJar = "F:\Program Files\Java\jre7\lib\rt.jar";
classDenpdencyFile = "F:\Program Files\Java\jre7\lib\classdepency.txt";
}
List<String> depencyClass = new ArrayList<String>();
BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(classDenpdencyFile)));
String templine = br.readLine();
// load all the dependency class and store them in a array list;
while(templine!=null) {
int end = templine.lastIndexOf("from");
int begin = templine.lastIndexOf("[Loaded")+7;
String className = templine.substring(begin,end).replace(".", "/").trim();
depencyClass.add(className);
templine= br.readLine();
}
JarFile zipIn = new JarFile(mainJar);
InputStream readin = null;
JarOutputStream jos = new JarOutputStream(new FileOutputStream("rt.jar"));
JarInputStream jis = new JarInputStream(new FileInputStream(mainJar));
JarEntry entry = jis.getNextJarEntry();
while(entry!=null) {
String name = entry.getName();
//remove the .class suffix.
name = name.substring(0,name.lastIndexOf("."));
if(depencyClass.contains(name)) {
//put an entry record and write the binary data
jos.putNextEntry(entry);
readin = zipIn.getInputStream(entry);
byte[] temp = new byte[4096];
int count = readin.read(temp);
while (count != -1) {
jos.write(temp, 0, count);
count = readin.read(temp);
}
readin.close();
}
entry = jis.getNextJarEntry();
}
jis.close();
jos.close();
}
}
extractZIPFile 把spPath指定的ZIP文件解压到destinationDir，如果指定了fileIdentifier，那么久解压指定的文件,否则解压全部文件。
private String extractZIPFile(String spPath, String destinationDir, String fileIdentifier) throws IOException {
ZipFile zip = new ZipFile(spPath);
String rootfolderPath = null;
FileOutputStream fos = null;
InputStream readin = null;
/*create the destination folder if it is non-existed.*/
File destFolder = new File(destinationDir);
if (!destFolder.exists()) {
destFolder.mkdirs();
}
try {
for (Enumeration<? extends ZipEntry> enums = zip.entries(); enums.hasMoreElements(); ) {
ZipEntry entry = (ZipEntry) enums.nextElement();
/*if specified the identifier and the current entry does not match it. then just skip this entry*/
if (fileIdentifier != null) {
if (!entry.getName().contains(fileIdentifier)) {
continue;
} else {
String fileName = destinationDir + separator + entry.getName().substring(entry.getName().lastIndexOf("/"));
File f = new File(fileName);
rootfolderPath = f.getCanonicalPath();
readin = zip.getInputStream(entry);
fos = new FileOutputStream(f);
byte[] temp = new byte[BUFFER_SIZE];
int count = readin.read(temp);
while (count != -1) {
fos.write(temp, 0, count);
count = readin.read(temp);
}
/*need to close the fos/readin as the fos/readin will be refer to another entry next time*/
fos.close();
readin.close();
}
} else {
String fileName = destinationDir + separator + entry.getName();
File f = new File(fileName);
if (entry.isDirectory()) {
f.mkdirs();
if (rootfolderPath == null) {
rootfolderPath = f.getCanonicalPath();
}
} else {
readin = zip.getInputStream(entry);
fos = new FileOutputStream(f);
byte[] temp = new byte[BUFFER_SIZE];
int count = readin.read(temp);
while (count != -1) {
fos.write(temp, 0, count);
count = readin.read(temp);
}
/*need to close the fos/readin as the fos/readin will be refer to another entry next time*/
fos.close();
readin.close();
}
}
}
return rootfolderPath;
} catch (Exception e) {
log.error("Bad file format: " + spPath, e);
return null;
} finally {
UpgradeUtils.close(readin, fos);
zip.close();
}
}