获取 apk 文件注释里的渠道号

ZipCommentHelper

package com.github.nukc.plugin;

import java.io.DataInput;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.Arrays;

/**
 * Created by Nukc.
 * Base on https://github.com/mcxiaoke/packer-ng-plugin/blob/master/helper/src/main/java/com/mcxiaoke/packer/helper/PackerNg.java
 */
public class ZipCommentHelper {

    private static final byte[] COMMENT_SIGN = new byte[]{99, 104, 97, 110, 110, 101, 108}; //channel
    private static final String EMPTY_STRING = "";
    private static String sCachedChannel;

    public static String getChannel(final Object context) {
        return getChannel(context, EMPTY_STRING);
    }

    public static synchronized String getChannel(final Object context, final String defaultValue) {
        if (sCachedChannel == null) {
            sCachedChannel = getChannelInternal(context, defaultValue).channel;
        }
        return sCachedChannel;
    }

    public static ChannelInfo getChannelInfo(final Object context) {
        return getChannelInfo(context, EMPTY_STRING);
    }

    public static synchronized ChannelInfo getChannelInfo(final Object context, final String defaultValue) {
        return getChannelInternal(context, defaultValue);
    }

    private static ChannelInfo getChannelInternal(final Object context, final String defaultValue) {
        String market;
        Exception error;
        try {
            final String sourceDir = getSourceDir(context);
            market = readZipComment(new File(sourceDir));
            error = null;
        } catch (Exception e) {
            market = null;
            error = e;
        }
        return new ChannelInfo(market == null ? defaultValue : market, error);
    }

    public static final class ChannelInfo {
        public final String channel;
        public final Exception error;

        public ChannelInfo(final String channel, final Exception error) {
            this.channel = channel;
            this.error = error;
        }

        @Override
        public String toString() {
            return "ChannelInfo{" +
                    "channel='" + channel + '\'' +
                    ", error=" + error +
                    '}';
        }
    }

    // for android code
    private static String getSourceDir(final Object context) throws ClassNotFoundException,
            InvocationTargetException, IllegalAccessException, NoSuchFieldException, NoSuchMethodException {
        final Class<?> contextClass = Class.forName("android.content.Context");
        final Class<?> applicationInfoClass = Class.forName("android.content.pm.ApplicationInfo");
        final Method getApplicationInfoMethod = contextClass.getMethod("getApplicationInfo");
        final Object appInfo = getApplicationInfoMethod.invoke(context);
        // try ApplicationInfo.publicSourceDir
        final Field publicSourceDirField = applicationInfoClass.getField("publicSourceDir");
        String sourceDir = (String) publicSourceDirField.get(appInfo);
        if (sourceDir == null) {
            // try ApplicationInfo.sourceDir
            final Field sourceDirField = applicationInfoClass.getField("sourceDir");
            sourceDir = (String) sourceDirField.get(appInfo);
        }
        if (sourceDir == null) {
            // try Context.getPackageCodePath()
            final Method getPackageCodePathMethod = contextClass.getMethod("getPackageCodePath");
            sourceDir = (String) getPackageCodePathMethod.invoke(context);
        }
        return sourceDir;
    }


    private static String readZipComment(File file) throws IOException {
        RandomAccessFile raf = null;
        try {
            raf = new RandomAccessFile(file, "r");
            long index = raf.length();
            byte[] buffer = new byte[COMMENT_SIGN.length];
            index -= COMMENT_SIGN.length;
            // read sign bytes
            raf.seek(index);
            raf.readFully(buffer);
            // if sign bytes matched
            if (Arrays.equals(buffer, COMMENT_SIGN)) {
                index -= 2;
                raf.seek(index);
                // read content length field
                int length = readShort(raf);
                if (length > 0) {
                    index -= length;
                    raf.seek(index);
                    // read content bytes
                    byte[] bytesComment = new byte[length];
                    raf.readFully(bytesComment);
                    return new String(bytesComment, "utf-8");
                } else {
                    throw new IOException("Zip comment content not found");
                }
            } else {
                throw new IOException("Zip comment sign bytes not found");
            }
        } finally {
            if (raf != null) {
                raf.close();
            }
        }
    }

    private static short readShort(DataInput input) throws IOException {
        byte[] buf = new byte[2];
        input.readFully(buf);
        ByteBuffer bb = ByteBuffer.wrap(buf).order(ByteOrder.LITTLE_ENDIAN);
        return bb.getShort(0);
    }
}