Java IO.pdf - Nguyen Dang Binh

Figure 9.4. The java.util.jar package hierarchy
Java I/O
All of these classes are used much like their superclasses are. For instance, to read a JAR file,
follow these steps:
1. Construct a JarInputStream object from an underlying stream, most commonly a file
input stream.
2. Open the next JAR entry in the archive.
3. Read data from the JAR entry using InputStream methods like read().
4. Close the JAR entry (optional)
5. Repeat steps 2 through 4 as long as there are more entries (files) remaining in the
archive.
6. Close the JAR input stream.
These are the same six steps you use to read a zip file, only with the java.util.zip classes
replaced by their counterparts in java.util.jar. Even that much is unnecessary. All the
standard zip tools as well as the programs developed in this chapter can work equally well
with JAR files. However, the java.util.jar classes do provide some extra convenience
methods for reading and writing manifest entries.
9.5.4 JarFile
The java.util.jar.JarFile class represents a file in the JAR format. It is a subclass of
java.util.zip.ZipFile, and JarFile objects are almost exactly like ZipFile objects.
public class JarFile extends ZipFile // Java 2
The JarFile class has four constructors:
180