Android應用增量升級
阿新 • • 發佈：2018-12-23
何為增量升級，簡單說下，當應用版本要更新時通常的做法是重新下載新的版本去覆蓋舊版本，但這樣有個比較明顯缺點，太浪費流量了，尤其是在GPRS模式下。我們能不能只更新新版本增加的內容呢，bsdiff/bzlib2可以幫助我們實現這點。下面介紹下具體的做法
第一、生成舊版和新版的差分比patch檔案，可以藉助bsdiff開源庫windows版本
bsdiff.exe ../iReader1.6.2.0(v35).apk ../iReader1.8.0.1(v40).apk ../ireader.patch第二、有了patch檔案，我們就可以在Android平臺上利用JNI呼叫bzlib2就可以實現增量升級了。
2、編寫本地方法
//oldapk_filepath：舊版本儲存路徑 newapk_savepath：生成的新版本要存放的路徑 patchpath:差分比檔案存放路徑
public native int applyPatchToOldApk(String oldapk_filepath, String newapk_savepath , String patchpath);
4、實現本地方法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. # 具體到底需要哪些c程式碼，沒有仔細研究過 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)
#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 升級之前apk包路徑 // new 升級之後apk包路徑 // patch檔案，可以用bsdiff工具生成 // 具體原理可以參看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; }
最後 ndk編譯，在Android中呼叫native方法，你會發現在你傳入路徑下生成了新版本的apk。