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Java Module java.base Package java.util.jar Class JarInputStream（JDK11）

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Module java.base
Package java.util.jar

Class JarInputStream

  • All Implemented Interfaces:
    Closeable, AutoCloseable
    public class JarInputStream
extends ZipInputStream
    The JarInputStream class is used to read the contents of a JAR file from any input stream. It extends the class java.util.zip.ZipInputStream with support for reading an optional Manifest entry. The Manifest can be used to store meta-information about the JAR file and its entries.
    Since:
    1.2
    See Also:
    Manifest, ZipInputStream

    • Constructor Detail

      • JarInputStream

        public JarInputStream​(InputStream in)
               throws IOException
        Creates a new JarInputStream and reads the optional manifest. If a manifest is present, also attempts to verify the signatures if the JarInputStream is signed.
        Parameters:
        in - the actual input stream
        Throws:
        IOException - if an I/O error has occurred

      • JarInputStream

        public JarInputStream​(InputStream in,
                      boolean verify)
               throws IOException
        Creates a new JarInputStream and reads the optional manifest. If a manifest is present and verify is true, also attempts to verify the signatures if the JarInputStream is signed.
        Parameters:
        in - the actual input stream
        verify - whether or not to verify the JarInputStream if it is signed.
        Throws:
        IOException - if an I/O error has occurred

    • Method Detail

      • getManifest

        public Manifest getManifest()
        Returns the Manifest for this JAR file, or null if none.
        Returns:
        the Manifest for this JAR file, or null if none.

      • getNextEntry

        public ZipEntry getNextEntry()
                      throws IOException
        Reads the next ZIP file entry and positions the stream at the beginning of the entry data. If verification has been enabled, any invalid signature detected while positioning the stream for the next entry will result in an exception.
        Overrides:
        getNextEntry in class ZipInputStream
        Returns:
        the next ZIP file entry, or null if there are no more entries
        Throws:
        ZipException - if a ZIP file error has occurred
        IOException - if an I/O error has occurred
        SecurityException - if any of the jar file entries are incorrectly signed.

      • getNextJarEntry

        public JarEntry getNextJarEntry()
                         throws IOException
        Reads the next JAR file entry and positions the stream at the beginning of the entry data. If verification has been enabled, any invalid signature detected while positioning the stream for the next entry will result in an exception.
        Returns:
        the next JAR file entry, or null if there are no more entries
        Throws:
        ZipException - if a ZIP file error has occurred
        IOException - if an I/O error has occurred
        SecurityException - if any of the jar file entries are incorrectly signed.

      • read

        public int read​(byte[] b,
                int off,
                int len)
         throws IOException
        Reads from the current JAR file entry into an array of bytes. If len is not zero, the method blocks until some input is available; otherwise, no bytes are read and 0 is returned. If verification has been enabled, any invalid signature on the current entry will be reported at some point before the end of the entry is reached.
        Overrides:
        read in class ZipInputStream
        Parameters:
        b - the buffer into which the data is read
        off - the start offset in the destination array b
        len - the maximum number of bytes to read
        Returns:
        the actual number of bytes read, or -1 if the end of the entry is reached
        Throws:
        NullPointerException - If b is null.
        IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than b.length - off
        ZipException - if a ZIP file error has occurred
        IOException - if an I/O error has occurred
        SecurityException - if any of the jar file entries are incorrectly signed.
        See Also:
        FilterInputStream.in

      • createZipEntry

        protected ZipEntry createZipEntry​(String name)
        Creates a new JarEntry (ZipEntry) for the specified JAR file entry name. The manifest attributes of the specified JAR file entry name will be copied to the new JarEntry.
        Overrides:
        createZipEntry in class ZipInputStream
        Parameters:
        name - the name of the JAR/ZIP file entry
        Returns:
        the JarEntry object just created

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