java.util.zip.ZipException：無效的通用標誌位：9

Question

我得到這個錯誤在Android 6.0

java.util.zip.ZipException: Invalid General Purpose Bit Flag: 9 java.util.zip.ZipInputStream.getNextEntry(ZipInputStream.java:253)

這是我的代碼：

ZipInputStream zin = new ZipInputStream(getAppContext().getContentResolver().openInputStream(uri)); 

是什麼意思？我究竟做錯了什麼？

Answer 1

這裏的ZIP文件規範：

Flags General purpose bit flag: 
Bit 00: encrypted file 
Bit 01: compression option 
Bit 02: compression option 
Bit 03: data descriptor 
Bit 04: enhanced deflation 
Bit 05: compressed patched data 
Bit 06: strong encryption 
Bit 07-10: unused 
Bit 11: language encoding 
Bit 12: reserved 
Bit 13: mask header values 
Bit 14-15: reserved 

所以，9:1的GPBF值既具有「加密文件」，並設置「數據描述符」位。

在Android源代碼這裏一個偷看： https://chromium.googlesource.com/android_tools/+/9e9b6169a098bc19986e44fbbf65e4c29031e4bd/sdk/sources/android-22/java/util/zip/ZipFile.java （舊版本，但我懷疑這並沒有改變）顯示了這一點：

static final int GPBF_ENCRYPTED_FLAG = 1 << 0; 

[...]

/** 
* Supported General Purpose Bit Flags Mask. 
* Bit mask of bits not supported. 
* Note: The only bit that we will enforce at this time 
* is the encrypted bit. Although other bits are not supported, 
* we must not enforce them as this could break some legitimate 
* use cases (See http://b/8617715). 
*/ 
static final int GPBF_UNSUPPORTED_MASK = GPBF_ENCRYPTED_FLAG; 

[...]

// At position 6 we find the General Purpose Bit Flag. 
int gpbf = Short.reverseBytes(is.readShort()) & 0xffff; 
if ((gpbf & ZipFile.GPBF_UNSUPPORTED_MASK) != 0) { 
    throw new ZipException("Invalid General Purpose Bit Flag: " + gpbf); 
} 

所以，你的ZIP文件CL旨在對文件進行加密（設置GPBF的位00），並且ZipFile實現不支持讀取加密文件。