Android应用增量升级

http://blog.csdn.net/tibib/article/details/8538592

阅读此文之前请先阅读  http://blog.csdn.net/hmg25/article/details/8100896

何为增量升级，简单说下，当应用版本要更新时通常的做法是重新下载新的版本去覆盖旧版本，但这样有个比较明显缺点，太浪费流量了，尤其是在GPRS模式下。我们能不能只更新新版本增加的内容呢，bsdiff/bzlib2可以帮助我们实现这点。下面介绍下具体的做法

第一、生成旧版和新版的差分比patch文件，可以借助bsdiff开源库windows版本

   bsdiff.exe   ../iReader1.6.2.0(v35).apk   ../iReader1.8.0.1(v40).apk   ../ireader.patch

第二、有了patch文件，我们就可以在Android平台上利用JNI调用bzlib2就可以实现增量升级了。

1、首先要有ndk编译环境，具体怎么搭建详见：http://blog.csdn.net/tibib/article/details/8504680

2、编写本地方法

	//oldapk_filepath：旧版本存储路径   newapk_savepath：生成的新版本要存放的路径  patchpath:差分比文件存放路径
	public native int applyPatchToOldApk(String oldapk_filepath, String newapk_savepath , String patchpath);
	

3、编写Android.mk配置文件，并把需要的bzlib2源代码文件()拷贝到目录下

LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)

# This is the target being built.
LOCAL_MODULE:= libBsdiff


# All of the source files that we will compile.
# 具体到底需要哪些c代码，没有仔细研究过
LOCAL_SRC_FILES:= tu_bingbing_bsdiff_BsdiffBusiness.c \
				  bzlib.c \
  				  blocksort.c \
  				  compress.c \
  				  crctable.c \
  				  decompress.c \
  				  huffman.c \
  				  randtable.c \
  				  bzip2.c \
  				    	
# No static libraries.
LOCAL_STATIC_LIBRARIES := \
     libbz


# Also need the JNI headers.
LOCAL_C_INCLUDES += \
    $(JNI_H_INCLUDE) external/bzip2

# No special compiler flags.
LOCAL_CFLAGS +=

include $(BUILD_SHARED_LIBRARY)

4、实现本地方法

#include <stdio.h>
#include "tu_bingbing_bsdiff_BsdiffBusiness.h"

#include "bzlib_private.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <err.h>
#include <unistd.h>
#include <fcntl.h>
#include <android/log.h>


static off_t offtin(u_char *buf)
{
    off_t y;

    y=buf[7]&0x7F;
    y=y*256;y+=buf[6];
    y=y*256;y+=buf[5];
    y=y*256;y+=buf[4];
    y=y*256;y+=buf[3];
    y=y*256;y+=buf[2];
    y=y*256;y+=buf[1];
    y=y*256;y+=buf[0];

    if(buf[7]&0x80) y=-y;

    return y;
}

int applypatch(int argc,char * argv[])
{
    FILE * f, * cpf, * dpf, * epf;
    BZFILE * cpfbz2, * dpfbz2, * epfbz2;
    int cbz2err, dbz2err, ebz2err;
    int fd;
    ssize_t oldsize,newsize;
    ssize_t bzctrllen,bzdatalen;
    u_char header[32],buf[8];
    u_char *old, *new;
    off_t oldpos,newpos;
    off_t ctrl[3];
    off_t lenread;
    off_t i;

    if(argc!=4) errx(1,"usage: %s oldfile newfile patchfile\n",argv[0]);

    /* Open patch file */
    if ((f = fopen(argv[3], "r")) == NULL)
        err(1, "fopen(%s)", argv[3]);

    /*
    File format:
        0   8   "BSDIFF40"
        8   8   X
        16  8   Y
        24  8   sizeof(newfile)
        32  X   bzip2(control block)
        32+X    Y   bzip2(diff block)
        32+X+Y  ??? bzip2(extra block)
    with control block a set of triples (x,y,z) meaning "add x bytes
    from oldfile to x bytes from the diff block; copy y bytes from the
    extra block; seek forwards in oldfile by z bytes".
    */

    /* Read header */
    if (fread(header, 1, 32, f) < 32) {
        if (feof(f))
            errx(1, "Corrupt patch\n");
        err(1, "fread(%s)", argv[3]);
    }

    /* Check for appropriate magic */
    if (memcmp(header, "BSDIFF40", 8) != 0)
        errx(1, "Corrupt patch\n");

    /* Read lengths from header */
    bzctrllen=offtin(header+8);
    bzdatalen=offtin(header+16);
    newsize=offtin(header+24);
    if((bzctrllen<0) || (bzdatalen<0) || (newsize<0))
        errx(1,"Corrupt patch\n");

    /* Close patch file and re-open it via libbzip2 at the right places */
    if (fclose(f))
        err(1, "fclose(%s)", argv[3]);
    if ((cpf = fopen(argv[3], "r")) == NULL)
        err(1, "fopen(%s)", argv[3]);
    if (fseeko(cpf, 32, SEEK_SET))
        err(1, "fseeko(%s, %lld)", argv[3],
            (long long)32);
    if ((cpfbz2 = BZ2_bzReadOpen(&cbz2err, cpf, 0, 0, NULL, 0)) == NULL)
        errx(1, "BZ2_bzReadOpen, bz2err = %d", cbz2err);
    if ((dpf = fopen(argv[3], "r")) == NULL)
        err(1, "fopen(%s)", argv[3]);
    if (fseeko(dpf, 32 + bzctrllen, SEEK_SET))
        err(1, "fseeko(%s, %lld)", argv[3],
            (long long)(32 + bzctrllen));
    if ((dpfbz2 = BZ2_bzReadOpen(&dbz2err, dpf, 0, 0, NULL, 0)) == NULL)
        errx(1, "BZ2_bzReadOpen, bz2err = %d", dbz2err);
    if ((epf = fopen(argv[3], "r")) == NULL)
        err(1, "fopen(%s)", argv[3]);
    if (fseeko(epf, 32 + bzctrllen + bzdatalen, SEEK_SET))
        err(1, "fseeko(%s, %lld)", argv[3],
            (long long)(32 + bzctrllen + bzdatalen));
    if ((epfbz2 = BZ2_bzReadOpen(&ebz2err, epf, 0, 0, NULL, 0)) == NULL)
        errx(1, "BZ2_bzReadOpen, bz2err = %d", ebz2err);

    if(((fd=open(argv[1],O_RDONLY,0))<0) ||
        ((oldsize=lseek(fd,0,SEEK_END))==-1) ||
        ((old=malloc(oldsize+1))==NULL) ||
        (lseek(fd,0,SEEK_SET)!=0) ||
        (read(fd,old,oldsize)!=oldsize) ||
        (close(fd)==-1)) err(1,"%s",argv[1]);
    if((new=malloc(newsize+1))==NULL) err(1,NULL);

    oldpos=0;newpos=0;
    while(newpos<newsize) {
        /* Read control data */
        for(i=0;i<=2;i++) {
            lenread = BZ2_bzRead(&cbz2err, cpfbz2, buf, 8);
            if ((lenread < 8) || ((cbz2err != BZ_OK) &&
                (cbz2err != BZ_STREAM_END)))
                errx(1, "Corrupt patch\n");
            ctrl[i]=offtin(buf);
        };

        /* Sanity-check */
        if(newpos+ctrl[0]>newsize)
            errx(1,"Corrupt patch\n");

        /* Read diff string */
        lenread = BZ2_bzRead(&dbz2err, dpfbz2, new + newpos, ctrl[0]);
        if ((lenread < ctrl[0]) ||
            ((dbz2err != BZ_OK) && (dbz2err != BZ_STREAM_END)))
            errx(1, "Corrupt patch\n");

        /* Add old data to diff string */
        for(i=0;i<ctrl[0];i++)
            if((oldpos+i>=0) && (oldpos+i<oldsize))
                new[newpos+i]+=old[oldpos+i];

        /* Adjust pointers */
        newpos+=ctrl[0];
        oldpos+=ctrl[0];

        /* Sanity-check */
        if(newpos+ctrl[1]>newsize)
            errx(1,"Corrupt patch\n");

        /* Read extra string */
        lenread = BZ2_bzRead(&ebz2err, epfbz2, new + newpos, ctrl[1]);
        if ((lenread < ctrl[1]) ||
            ((ebz2err != BZ_OK) && (ebz2err != BZ_STREAM_END)))
            errx(1, "Corrupt patch\n");

        /* Adjust pointers */
        newpos+=ctrl[1];
        oldpos+=ctrl[2];
    };

    /* Clean up the bzip2 reads */
    BZ2_bzReadClose(&cbz2err, cpfbz2);
    BZ2_bzReadClose(&dbz2err, dpfbz2);
    BZ2_bzReadClose(&ebz2err, epfbz2);
    if (fclose(cpf) || fclose(dpf) || fclose(epf))
        err(1, "fclose(%s)", argv[3]);

    /* Write the new file */
    if(((fd=open(argv[2],O_CREAT|O_TRUNC|O_WRONLY,0666))<0) ||
        (write(fd,new,newsize)!=newsize) || (close(fd)==-1))
        err(1,"%s",argv[2]);

    free(new);
    free(old);

    return 0;
}

// old 升级之前apk包路径
// new 升级之后apk包路径
// patch文件，可以用bsdiff工具生成
// 具体原理可以参看http://blog.csdn.net/hmg25/article/details/8100896
JNIEXPORT jint JNICALL Java_tu_bingbing_bsdiff_BsdiffBusiness_applyPatchToOldApk(JNIEnv *env,
        jobject obj, jstring old, jstring new , jstring patch){
  int argc=4;
  char * argv[argc];
  argv[0]="bspatch";
  argv[1]=(char*)((*env)->GetStringUTFChars(env,old, 0));
  argv[2]=(char*)((*env)->GetStringUTFChars(env,new, 0));
  argv[3]=(char*)((*env)->GetStringUTFChars(env,patch, 0));

  int ret=applypatch(argc, argv);

   (*env)->ReleaseStringUTFChars(env,old,argv[1]);
   (*env)->ReleaseStringUTFChars(env,new,argv[2]);
   (*env)->ReleaseStringUTFChars(env,patch,argv[3]);
   return ret;
}

 

最后 ndk编译，在Android中调用native方法，你会发现在你传入路径下生成了新版本的apk。

DEMO：http://download.csdn.net/detail/tibib/5581905