如何在Java中实用地从jar中删除特定的文件/文件夹 [英] How to delete a specific File/Folder from a jar pragmatically in java
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问题描述
如何用Java实用地从jar中删除特定的文件/文件夹.
How to delete a specific File/Folder from a jar pragmatically in java.
我有一个jar ABC.jar包含文件,文件夹和另一个jar,例如child.jar. 在child.jar下,我想删除一个特定的文件.我能怎么做?这样我的ABC.jar结构保持不变.
I have a jar ABC.jar contains files, folder and another jars say child.jar. under child.jar I want to delete a specific file. How can I do? so that my ABC.jar structure remains same.
任何帮助将不胜感激.
Any help will be appreciate.
在此先感谢.
推荐答案
@icza回答,我们必须遍历原始jar文件并删除不需要的条目. 这是您可以参考的Java代码.
As answered by @icza we have to iterate through original jar file and deleting the entry we don't want. Here is the java code you can refer.
public static void main(String[] args) throws IOException {
String jarName = args[0];
String fileName = args[1];
// Create file descriptors for the jar and a temp jar.
File jarFile = new File(jarName);
File tempJarFile = new File(jarName + ".tmp");
// Open the jar file.
JarFile jar = new JarFile(jarFile);
System.out.println(jarName + " opened.");
// Initialize a flag that will indicate that the jar was updated.
boolean jarUpdated = false;
try {
// Create a temp jar file with no manifest. (The manifest will
// be copied when the entries are copied.)
Manifest jarManifest = jar.getManifest();
JarOutputStream tempJar =
new JarOutputStream(new FileOutputStream(tempJarFile));
// Allocate a buffer for reading entry data.
byte[] buffer = new byte[1024];
int bytesRead;
try {
// Open the given file.
FileInputStream file = new FileInputStream(fileName);
try {
// Create a jar entry and add it to the temp jar.
JarEntry entry = new JarEntry(fileName);
tempJar.putNextEntry(entry);
// Read the file and write it to the jar.
while ((bytesRead = file.read(buffer)) != -1) {
tempJar.write(buffer, 0, bytesRead);
}
System.out.println(entry.getName() + " added.");
}
finally {
file.close();
}
// Loop through the jar entries and add them to the temp jar,
// skipping the entry that was added to the temp jar already.
for (Enumeration entries = jar.entries(); entries.hasMoreElements(); ) {
// Get the next entry.
JarEntry entry = (JarEntry) entries.nextElement();
// If the entry has not been added already, add it.
if (! entry.getName().equals(fileName)) {
// Get an input stream for the entry.
InputStream entryStream = jar.getInputStream(entry);
// Read the entry and write it to the temp jar.
tempJar.putNextEntry(entry);
while ((bytesRead = entryStream.read(buffer)) != -1) {
tempJar.write(buffer, 0, bytesRead);
}
}
}
jarUpdated = true;
}
catch (Exception ex) {
System.out.println(ex);
// Add a stub entry here, so that the jar will close without an
// exception.
tempJar.putNextEntry(new JarEntry("stub"));
}
finally {
tempJar.close();
}
}
finally {
jar.close();
System.out.println(jarName + " closed.");
// If the jar was not updated, delete the temp jar file.
if (! jarUpdated) {
tempJarFile.delete();
}
}
// If the jar was updated, delete the original jar file and rename the
// temp jar file to the original name.
if (jarUpdated) {
jarFile.delete();
tempJarFile.renameTo(jarFile);
System.out.println(jarName + " updated.");
}
}
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