# Class UDecoder

java.lang.Object
org.apache.tomcat.util.buf.UDecoder

public final class UDecoder extends Object
All URL decoding happens here. This way we can reuse, review, optimize without adding complexity to the buffers. The conversion will modify the original buffer.

Author:
  Costin Manolache

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `UDecoder()`

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `convert(ByteChunk mb, boolean query)`
  URLDecode, will modify the source.
  `void`
  `convert(ByteChunk mb, EncodedSolidusHandling encodedSolidusHandling)`
  Deprecated.
  Unused.
  `void`
  `convert(ByteChunk mb, EncodedSolidusHandling encodedSolidusHandling, EncodedSolidusHandling encodedReverseSolidusHandling)`
  URLDecode, will modify the source.
  `static String`
  `URLDecode(String str, Charset charset)`
  Decode and return the specified URL-encoded String.
  `static String`
  `URLDecode(String str, Charset charset, EncodedSolidusHandling encodedSolidusHandling, EncodedSolidusHandling encodedReverseSolidusHandling)`
  Decode and return the specified URL-encoded String.

  ### Methods inherited from class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Constructor Details

  - ### UDecoder

    public UDecoder()

- ## Method Details

  - ### convert

    public void convert(ByteChunk mb, boolean query) throws IOException
    URLDecode, will modify the source. Assumes source bytes are encoded using a superset of US-ASCII as per RFC 7230. "%5c" will be decoded. "%2f" will be rejected unless the input is a query string.
    Parameters:
      `mb` - The URL encoded bytes
      `query` - `true` if this is a query string. For a query string '+' will be decoded to ' '
    Throws:
      `IOException` - Invalid %xx URL encoding

  - ### convert

    @Deprecated public void convert(ByteChunk mb, EncodedSolidusHandling encodedSolidusHandling) throws IOException
    Deprecated.
    Unused. Will be removed in Tomcat 12. Use `convert(ByteChunk, EncodedSolidusHandling, EncodedSolidusHandling)`
    URLDecode, will modify the source. Assumes source bytes are encoded using a superset of US-ASCII as per RFC 7230.
    Parameters:
      `mb` - The URL encoded bytes
      `encodedSolidusHandling` - How should the %2f sequence handled by the decoder? For query strings this parameter will be ignored and the %2f sequence will be decoded
    Throws:
      `IOException` - Invalid %xx URL encoding

  - ### convert

    public void convert(ByteChunk mb, EncodedSolidusHandling encodedSolidusHandling, EncodedSolidusHandling encodedReverseSolidusHandling) throws IOException
    URLDecode, will modify the source. Assumes source bytes are encoded using a superset of US-ASCII as per RFC 7230.
    Parameters:
      `mb` - The URL encoded bytes
      `encodedSolidusHandling` - How should the %2f sequence handled by the decoder? For query strings this parameter will be ignored and the %2f sequence will be decoded
      `encodedReverseSolidusHandling` - How should the %5c sequence handled by the decoder? For query strings this parameter will be ignored and the %5c sequence will be decoded
    Throws:
      `IOException` - Invalid %xx URL encoding

  - ### URLDecode

    public static String URLDecode(String str, Charset charset)
    Decode and return the specified URL-encoded String. It is assumed the string is not a query string.
    Parameters:
      `str` - The url-encoded string
      `charset` - The character encoding to use; if null, UTF-8 is used.
    Returns:
      the decoded string
    Throws:
      `IllegalArgumentException` - if a '%' character is not followed by a valid 2-digit hexadecimal number

  - ### URLDecode

    public static String URLDecode(String str, Charset charset, EncodedSolidusHandling encodedSolidusHandling, EncodedSolidusHandling encodedReverseSolidusHandling)
    Decode and return the specified URL-encoded String. It is assumed the string is not a query string.
    Parameters:
      `str` - The url-encoded string
      `charset` - The character encoding to use; if null, UTF-8 is used.
      `encodedSolidusHandling` - The required handling of encoded solidus (%2f - /)
      `encodedReverseSolidusHandling` - The required handling of encoded reverse solidus (%5c - \)
    Returns:
      the decoded string
    Throws:
      `IllegalArgumentException` - if a '%' character is not followed by a valid 2-digit hexadecimal number