android解压带密码的zip包(android解压app)

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推荐整理分享android解压带密码的zip包(android解压app)，希望有所帮助，仅作参考，欢迎阅读内容。

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网上找到的资料，还没试过，谁要是试了回复下吧。

原文出自： a recent “fun” project, I needed my application to be able to access password-protected zip files of a particular format. It was one of these features I thought will take me no time to implement. Anyway, to my surprise, neither JDK supports password-protected ZIP files, nor I was able to find a suitable Java open source library I could use for that purpose. So, I ended up writing the utility class on my own. I wrote an implementation ofjava.io.InputStream that filters the ZIP file data and turns a password-protected ZIP into an unprotected one on the fly – so the stream can be nicely chained withjava.util.zip.ZipInputStream. Although the class is specifically targeted at the particular type of ZIP files I had to deal with (see the limitations below), maybe other people have to deal with the same type of files, or this class can provide a good start for others to turn it into a utility that would work with any type of ZIP (maybe I will do it myself some day – for now I don’t have time).To implement this class I used the ZIP File Format Specification as the source of information. I also used the 7-zip project (C&#;&#;) as a reference during the debugging to verify my understanding of the ZIP spec. and the CRC algorithm.So, here is the class:

?import java.io.IOException;import java.io.InputStream; public class ZipDecryptInputStream extendsInputStream { privatestatic final int[] CRC_TABLE = newint[]; // compute the table // (could also have it pre-computed - static{ for(int i = 0; i < ; i&#;&#;) { intr = i; for(int j = 0; j < 8; j&#;&#;) { if((r & 1) ==1) { r = (r >>>1) ^ 0xedb; }else { r >>>=1; } } CRC_TABLE[i] = r; } } privatestatic final int DECRYPT_HEADER_SIZE = ; privatestatic final int[] LFH_SIGNATURE = {0x,0x4b, 0x,0x}; privatefinal InputStream delegate; privatefinal String password; privatefinal int keys[] = new int[3]; privateState state = State.SIGNATURE; privateint skipBytes; privateint compressedSize; privateint value; privateint valuePos; privateint valueInc; publicZipDecryptInputStream(InputStream stream, String password) { this.delegate = stream; this.password = password; } @Override publicint read() throwsIOException { intresult = delegate.read(); if(skipBytes == 0) { switch(state) { caseSIGNATURE: if(result != LFH_SIGNATURE[valuePos]) { state = State.TAIL; }else { valuePos&#;&#;; if(valuePos >= LFH_SIGNATURE.length) { skipBytes =2; state = State.FLAGS; } } break; caseFLAGS: if((result & 1) ==0) { thrownew IllegalStateException("ZIP not password protected."); } if((result & ) ==) { thrownew IllegalStateException("Strong encryption used."); } if((result & 8) ==8) { thrownew IllegalStateException("Unsupported ZIP format."); } result -=1; compressedSize =0; valuePos =0; valueInc = DECRYPT_HEADER_SIZE; state = State.COMPRESSED_SIZE; skipBytes =; break; caseCOMPRESSED_SIZE: compressedSize &#;= result << (8* valuePos); result -= valueInc; if(result < 0) { valueInc =1; result &#;=; }else { valueInc =0; } valuePos&#;&#;; if(valuePos > 3) { valuePos =0; value =0; state = State.FN_LENGTH; skipBytes =4; } break; caseFN_LENGTH: caseEF_LENGTH: value &#;= result <<8 * valuePos; if(valuePos == 1) { valuePos =0; if(state == State.FN_LENGTH) { state = State.EF_LENGTH; }else { state = State.HEADER; skipBytes = value; } }else { valuePos =1; } break; caseHEADER: initKeys(password); for(int i = 0; i < DECRYPT_HEADER_SIZE; i&#;&#;) { updateKeys((byte) (result ^ decryptByte())); result = delegate.read(); } compressedSize -= DECRYPT_HEADER_SIZE; state = State.DATA; // intentionally no break caseDATA: result = (result ^ decryptByte()) &0xff; updateKeys((byte) result); compressedSize--; if(compressedSize == 0) { valuePos =0; state = State.SIGNATURE; } break; caseTAIL: // do nothing } }else { skipBytes--; } returnresult; } @Override publicvoid close() throwsIOException { delegate.close(); super.close(); } privatevoid initKeys(String password) { keys[0] =; keys[1] =; keys[2] =; for(int i = 0; i < password.length(); i&#;&#;) { updateKeys((byte) (password.charAt(i) &0xff)); } } privatevoid updateKeys(bytecharAt) { keys[0] = crc(keys[0], charAt); keys[1] &#;= keys[0] &0xff; keys[1] = keys[1] * &#; 1; keys[2] = crc(keys[2], (byte) (keys[1] >>)); } privatebyte decryptByte() { inttemp = keys[2] |2; return(byte) ((temp * (temp ^1)) >>> 8); } privateint crc(intoldCrc, byte charAt) { return((oldCrc >>> 8) ^ CRC_TABLE[(oldCrc ^ charAt) &0xff]); } privatestatic enum State { SIGNATURE, FLAGS, COMPRESSED_SIZE, FN_LENGTH, EF_LENGTH, HEADER, DATA, TAIL }}

These are the limitations:

Only the “Traditional PKWARE Encryption” is supported (spec. section VII)Files that have the “compressed length” information at the end of the data section (rather than at the beginning) are not supported (see “general purpose bit flag”, bit 3 in section V, subsection J in the spec.)

And this is how you can use it in your code:

?import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;import java.util.zip.ZipEntry;import java.util.zip.ZipInputStream; // usage: java Main [filename] [password]public class Main { publicstatic void main(String[] args) throws IOException { // password-protected zip file I need to read FileInputStream fis =new FileInputStream(args[0]); // wrap it in the decrypt stream ZipDecryptInputStream zdis =new ZipDecryptInputStream(fis, args[1]); // wrap the decrypt stream by the ZIP input stream ZipInputStream zis =new ZipInputStream(zdis); // read all the zip entries and save them as files ZipEntry ze; while((ze = zis.getNextEntry()) != null) { FileOutputStream fos =new FileOutputStream(ze.getName()); intb; while((b = zis.read()) != -1) { fos.write(b); } fos.close(); zis.closeEntry(); } zis.close(); }}Previous Entry: Jersey Hands-On LabNext Entry: Jersey and Cross-Site Request Forgery (CSRF)

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