解壓編碼

㈠ 文件解壓過後是亂碼，為什麼

重新下載,你所下載的解壓文件沒有下載成功而只下載了一個壓縮包.
另外也可能是一個壓縮包內有幾個軟體，但是軟體卻是分開的。
也就是說你必須下完所有的壓縮包才能從一個壓縮包中解壓出所有的文件。
很多網站上為了多一次下載點擊都會這樣，把一個文件分成2個壓縮，但是一個壓縮里你能看到2個但是卻無法解壓出2個文件，因為另一個文件的實體在另一個壓縮包里，這也就會出現亂碼.

㈡ 壓縮文件解壓出來是亂碼

打開壓縮包的文件，只能是先將壓縮包解壓，然後雙擊才能正常打開。如果是直接雙擊壓縮包里的文件，不知是什麼原因，雙擊壓縮包里的文檔、圖片都不能正常打開，打開後全部顯示是亂碼。為什麼雙擊壓縮包里的文件，會是亂碼呢?原因就在於誤設置了使用WinRAR的查看器來打開壓縮包里的文件。

可以先啟動WinRAR軟體，然後單擊上面的菜單「選項」→「設置」→「查看器」選項卡，在「查看器類型」欄目里選中「關聯程序」選項即可解決雙擊打開壓縮文件為亂碼的問題。

㈢ 解壓文件解壓都是亂碼，具體看下圖

壓縮文件損壞了，重新下載吧。

㈣ 如何解壓文件名是UTF8編碼的壓縮包

UTF8其實和Unicode是同類，就是在編碼方式上不同！
首先UTF8編碼後的大小是不一定，不像Unicode編碼後的大小是一樣的！

我們先來看Unicode的編碼：一個英文字母 「a」 和 一個漢字 「好」，編碼後都是佔用的空間大小是一樣的，都是兩個位元組！

而UTF8編碼：一個英文字母「a」 和 一個漢字 「好」，編碼後佔用的空間大小就不樣了，前者是一個位元組，後者是三個位元組！

現在就讓我們來看看UTF8編碼的原理吧：
因為一個字母還有一些鍵盤上的符號加起來只用二進制七位就可以表示出來，而一個位元組就是八位，所以UTF8就用一個位元組來表式字母和一些鍵盤上的符號。然而當我們拿到被編碼後的一個位元組後怎麼知道它的組成？它有可能是英文字母的一個位元組，也有可能是漢字的三個位元組中的一個位元組！所以，UTF8是有標志位的！

當要表示的內容是 7位 的時候就用一個位元組：0******* 第一個0為標志位，剩下的空間正好可以表示ASCII 0－127 的內容。

當要表示的內容在 8 到 11 位的時候就用兩個位元組：110***** 10****** 第一個位元組的110和第二個位元組的10為標志位。

當要表示的內容在 12 到 16 位的時候就用三個位元組：1110***** 10****** 10****** 和上面一樣，第一個位元組的1110和第二、三個位元組的10都是標志位，剩下的占湔�每梢員硎競鶴幀?BR>
以此類推：
四個位元組：11110**** 10****** 10****** 10******
五個位元組：111110*** 10****** 10****** 10****** 10******
六個位元組：1111110** 10****** 10****** 10****** 10****** 10******

UTF-7：A Mail-Safe Transformation Format of Unicode(RFC1642)。這是一種使用 7 位 ASCII 碼對 Unicode 碼進行轉換的編碼。它的設計目的仍然是為了在只能傳遞 7 為編碼的郵件網關中傳遞信息。 UTF-7 對英語字母、數字和常見符號直接顯示，而對其他符號用修正的 Base64 編碼。符號 + 和 - 號控制編碼過程的開始和暫停。所以亂碼中如果夾有英文單詞，並且相伴有 + 號和 - 號，這就有可能是 UTF-7 編碼。

關於UTF7的更多資料如下（都是英語的，如果想具體了解再看）：
UTF-7

A Mail-Safe Transformation Format of Unicode

Status of this Memo

This memo provides information for the Internet community. This memo
does not specify an Internet standard of any kind. Distribution of
this memo is unlimited.

Abstract

The Unicode Standard, version 2.0, and ISO/IEC 10646-1:1993(E) (as
amended) jointly define a character set (hereafter referred to as
Unicode) which encompasses most of the world's writing systems.
However, Internet mail (STD 11, RFC 822) currently supports only 7-
bit US ASCII as a character set. MIME (RFC 2045 through 2049) extends
Internet mail to support different media types and character sets,
and thus could support Unicode in mail messages. MIME neither defines
Unicode as a permitted character set nor specifies how it would be
encoded, although it does provide for the registration of additional
character sets over time.

This document describes a transformation format of Unicode that
contains only 7-bit ASCII octets and is intended to be readable by
humans in the limiting case that the document consists of characters
from the US-ASCII repertoire. It also specifies how this
transformation format is used in the context of MIME and RFC 1641,
"Using Unicode with MIME".

Motivation

Although other transformation formats of Unicode exist and could
conceivably be used in this context (most notably UTF-8, also known
as UTF-2 or UTF-FSS), they suffer the disadvantage that they use
octets in the range decimal 128 through 255 to encode Unicode
characters outside the US-ASCII range. Thus, in the context of mail,
those octets must themselves be encoded. This requires putting text
through two successive encoding processes, and leads to a significant
expansion of characters outside the US-ASCII range, putting non-
English speakers at a disadvantage. For example, using UTF-8 together

with the Quoted-Printable content transfer encoding of MIME
represents US-ASCII characters in one octet, but other characters may
require up to nine octets.

Overview

UTF-7 encodes Unicode characters as US-ASCII octets, together with
shift sequences to encode characters outside that range. For this
purpose, one of the characters in the US-ASCII repertoire is reserved
for use as a shift character.

Many mail gateways and systems cannot handle the entire US-ASCII
character set (those based on EBCDIC, for example), and so UTF-7
contains provisions for encoding characters within US-ASCII in a way
that all mail systems can accomodate.

UTF-7 should normally be used only in the context of 7 bit
transports, such as mail. In other contexts, straight Unicode or
UTF-8 is preferred.

See RFC 1641, "Using Unicode with MIME" for the overall specification
on usage of Unicode transformation formats with MIME.

Definitions

First, the definition of Unicode:

The 16 bit character set Unicode is defined by "The Unicode
Standard, Version 2.0". This character set is identical with the
character repertoire and coding of the international standard
ISO/IEC 10646-1:1993(E); Coded Representation Form=UCS-2;
Subset=300; Implementation Level=3, including the first 7
amendments to 10646 plus editorial corrections.

Note. Unicode 2.0 further specifies the use and interaction of
these character codes beyond the ISO standard. However, any valid
10646 sequence is a valid Unicode sequence, and vice versa;
Unicode supplies interpretations of sequences on which the ISO
standard is silent as to interpretation.

Next, some handy definitions of US-ASCII character subsets:

Set D (directly encoded characters) consists of the following
characters (derived from RFC 1521, Appendix B, which no longer
appears in RFC 2045): the upper and lower case letters A through Z
and a through z, the 10 digits 0-9, and the following nine special
characters (note that "+" and "=" are omitted):

Character ASCII & Unicode Value (decimal)
' 39
( 40
) 41
, 44
- 45
. 46
/ 47
: 58
? 63

Set O (optional direct characters) consists of the following
characters (note that "\" and "~" are omitted):

Character ASCII & Unicode Value (decimal)
! 33
" 34
# 35
$ 36
% 37
& 38
* 42
; 59
< 60
= 61
> 62
@ 64
[ 91
] 93
^ 94
_ 95
' 96
{ 123
| 124
} 125

Rationale. The characters "\" and "~" are omitted because they are
often redefined in variants of ASCII.

Set B (Modified Base 64) is the set of characters in the Base64
alphabet defined in RFC 2045, excluding the pad character "="
(decimal value 61).

Rationale. The pad character = is excluded because UTF-7 is designed
for use within header fields as set forth in RFC 2047. Since the only
readable encoding in RFC 2047 is "Q" (based on RFC 2045's Quoted-
Printable), the "=" character is not available for use (without a lot
of escape sequences). This was very unfortunate but unavoidable. The
"=" character could otherwise have been used as the UTF-7 escape
character as well (rather than using "+").

Note that all characters in US-ASCII have the same value in Unicode
when zero-extended to 16 bits.

UTF-7 Definition

A UTF-7 stream represents 16-bit Unicode characters using 7-bit US-
ASCII octets as follows:

Rule 1: (direct encoding) Unicode characters in set D above may be
encoded directly as their ASCII equivalents. Unicode characters in
Set O may optionally be encoded directly as their ASCII
equivalents, bearing in mind that many of these characters are
illegal in header fields, or may not pass correctly through some
mail gateways.

Rule 2: (Unicode shifted encoding) Any Unicode character sequence
may be encoded using a sequence of characters in set B, when
preceded by the shift character "+" (US-ASCII character value
decimal 43). The "+" signals that subsequent octets are to be
interpreted as elements of the Modified Base64 alphabet until a
character not in that alphabet is encountered. Such characters
include control characters such as carriage returns and line
feeds; thus, a Unicode shifted sequence always terminates at the
of a line. As a special case, if the sequence terminates with the
character "-" (US-ASCII decimal 45) then that character is
absorbed; other terminating characters are not absorbed and are
processed normally.

Note that if the first character after the shifted sequence is "-"
then an extra "-" must be present to terminate the shifted
sequence so that the actual "-" is not itself absorbed.

Rationale. A terminating character is necessary for cases where
the next character after the Modified Base64 sequence is part of
character set B or is itself the terminating character. It can
also enhance readability by delimiting encoded sequences.

Also as a special case, the sequence "+-" may be used to encode
the character "+". A "+" character followed immediately by any
character other than members of set B or "-" is an ill-formed
sequence.

Unicode is encoded using Modified Base64 by first converting
Unicode 16-bit quantities to an octet stream (with the most
significant octet first). Surrogate pairs (UTF-16) are converted
by treating each half of the pair as a separate 16 bit quantity
(i.e., no special treatment). Text with an odd number of octets is
ill-formed. ISO 10646 characters outside the range addressable via
surrogate pairs cannot be encoded.

Rationale. ISO/IEC 10646-1:1993(E) specifies that when characters
the UCS-2 form are serialized as octets, that the most significant
octet appear first. This is also in keeping with common network
practice of choosing a canonical format for transmission.

Rationale. The policy for code point allocation within ISO 10646
and Unicode is that the repertoires be kept synchronized. No code
points will be allocated in ISO 10646 outside the range
addressable by surrogate pairs.

Next, the octet stream is encoded by applying the Base64 content
transfer encoding algorithm as defined in RFC 2045, modified to
omit the "=" pad character. Instead, when encoding, zero bits are
added to pad to a Base64 character boundary. When decoding, any
bits at the end of the Modified Base64 sequence that do not
constitute a complete 16-bit Unicode character are discarded. If
such discarded bits are non-zero the sequence is ill-formed.

Rationale. The pad character "=" is not used when encoding
Modified Base64 because of the conflict with its use as an escape
character for the Q content transfer encoding in RFC 2047 header
fields, as mentioned above.

Rule 3: The space (decimal 32), tab (decimal 9), carriage return
(decimal 13), and line feed (decimal 10) characters may be
directly represented by their ASCII equivalents. However, note
that MIME content transfer encodings have rules concerning the use
of such characters. Usage that does not conform to the
restrictions of RFC 822, for example, would have to be encoded
using MIME content transfer encodings other than 7bit or 8bit,
such as quoted-printable, binary, or base64.

Given this set of rules, Unicode characters which may be encoded via
rules 1 or 3 take one octet per character, and other Unicode
characters are encoded on average with 2 2/3 octets per character

plus one octet to switch into Modified Base64 and an optional octet
to switch out.

Example. The Unicode sequence "A<NOT IDENTICAL TO><ALPHA>."
(hexadecimal 0041,2262,0391,002E) may be encoded as follows:

A+ImIDkQ.

Example. The Unicode sequence "Hi Mom -<WHITE SMILING FACE>-!"
(hexadecimal 0048, 0069, 0020, 004D, 006F, 006D, 0020, 002D, 263A,
002D, 0021) may be encoded as follows:

Hi Mom -+Jjo--!

Example. The Unicode sequence representing the Han characters for
the Japanese word "nihongo" (hexadecimal 65E5,672C,8A9E) may be
encoded as follows:

+ZeVnLIqe-