简书链接:官方加载多个dex的核心代码
文章字数：40,阅读全文大约需要1分钟

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56

private static List<MultiDexExtractor.ExtractedDex> performExtractions(File sourceApk, File dexDir) throws IOException {
    String extractedFilePrefix = sourceApk.getName() + ".classes";
    prepareDexDir(dexDir, extractedFilePrefix);
    List<MultiDexExtractor.ExtractedDex> files = new ArrayList();
    ZipFile apk = new ZipFile(sourceApk);

    try {
        int secondaryNumber = 2;

        for(ZipEntry dexFile = apk.getEntry("classes" + secondaryNumber + ".dex"); dexFile != null; dexFile = apk.getEntry("classes" + secondaryNumber + ".dex")) {
            String fileName = extractedFilePrefix + secondaryNumber + ".zip";
            MultiDexExtractor.ExtractedDex extractedFile = new MultiDexExtractor.ExtractedDex(dexDir, fileName);
            files.add(extractedFile);
            Log.i("MultiDex", "Extraction is needed for file " + extractedFile);
            int numAttempts = 0;
            boolean isExtractionSuccessful = false;

            while(numAttempts < 3 && !isExtractionSuccessful) {
                ++numAttempts;
                extract(apk, dexFile, extractedFile, extractedFilePrefix);

                try {
                    extractedFile.crc = getZipCrc(extractedFile);
                    isExtractionSuccessful = true;
                } catch (IOException var19) {
                    isExtractionSuccessful = false;
                    Log.w("MultiDex", "Failed to read crc from " + extractedFile.getAbsolutePath(), var19);
                }

                Log.i("MultiDex", "Extraction " + (isExtractionSuccessful ? "succeeded" : "failed") + " - length " + extractedFile.getAbsolutePath() + ": " + extractedFile.length() + " - crc: " + extractedFile.crc);
                if (!isExtractionSuccessful) {
                    extractedFile.delete();
                    if (extractedFile.exists()) {
                        Log.w("MultiDex", "Failed to delete corrupted secondary dex '" + extractedFile.getPath() + "'");
                    }
                }
            }

            if (!isExtractionSuccessful) {
                throw new IOException("Could not create zip file " + extractedFile.getAbsolutePath() + " for secondary dex (" + secondaryNumber + ")");
            }

            ++secondaryNumber;
        }
    } finally {
        try {
            apk.close();
        } catch (IOException var18) {
            Log.w("MultiDex", "Failed to close resource", var18);
        }

    }

    return files;
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39

private static void extract(ZipFile apk, ZipEntry dexFile, File extractTo, String extractedFilePrefix) throws IOException, FileNotFoundException {
    InputStream in = apk.getInputStream(dexFile);
    ZipOutputStream out = null;
    File tmp = File.createTempFile("tmp-" + extractedFilePrefix, ".zip", extractTo.getParentFile());
    Log.i("MultiDex", "Extracting " + tmp.getPath());

    try {
        out = new ZipOutputStream(new BufferedOutputStream(new FileOutputStream(tmp)));

        try {
            ZipEntry classesDex = new ZipEntry("classes.dex");
            classesDex.setTime(dexFile.getTime());
            out.putNextEntry(classesDex);
            byte[] buffer = new byte[16384];

            for(int length = in.read(buffer); length != -1; length = in.read(buffer)) {
                out.write(buffer, 0, length);
            }

            out.closeEntry();
        } finally {
            out.close();
        }

        if (!tmp.setReadOnly()) {
            throw new IOException("Failed to mark readonly \"" + tmp.getAbsolutePath() + "\" (tmp of \"" + extractTo.getAbsolutePath() + "\")");
        }

        Log.i("MultiDex", "Renaming to " + extractTo.getPath());
        if (!tmp.renameTo(extractTo)) {
            throw new IOException("Failed to rename \"" + tmp.getAbsolutePath() + "\" to \"" + extractTo.getAbsolutePath() + "\"");
        }
    } finally {
        closeQuietly(in);
        tmp.delete();
    }

}