Android增量更新（四）-客户端合并差分包生成新的apk安装包

目录：

        Android增量更新（一）-差分文件（Windows-part1）

        Android增量更新（二）-差分文件（Windows-part2）-dll动态库和jar包

        Android增量更新（三）-差分文件（Linux）-生成jar和.so库

        Android增量更新（四）-客户端合并差分包生成新的apk安装包

        前面已经实现了在服务器端（Windows和LLinux）生成差分包，并生成了相应的jar包和动态库，方便直接使用。增量更新算是完成了一半了，还差客户端对差分包的合并，现在就来介绍如何在客户端合并差分包生成新的apk安装包。

        合并差分包主要用到的是：bspatch.c(linux)和bzip2的源码。所以总的来说也不是很难。

一、创建Android项目（BsPatchYwl5320）

1.1、创建C++的Android项目，点击next直到完成。

1.2、添加NDK路径

1.3、编译并成功运行就表示C++的Android项目成功搭建好了

二、配置bspatch和bzip2源码并编译

2.1、删除系统生成的本地方法和c++文件，并添加bspatch.c和bzip2源码

2.2、修改CMakeLists.txt配置来编译c代码并设置生成.so库的名称（BsPatchYwl5320）

2.2.1、添加bspatch.c和bzip2中的.c路径有2中方法。

第一种是在add_library中添加所以.c路径，如：

add_library( # Sets the name of the library.
             BsPatchYwl5320

             # Sets the library as a shared library.
             SHARED

             # Provides a relative path to your source file(s).
             src/main/cpp/bspatch.c
             src/main/cpp/bzip2/blocksort.c
             src/main/cpp/bzip2/bzip2.c
             ... #添加完所有.c文件
             )

这种方法对源文件个数较少的时候适用，当个数多了时，既难写又容易出错。

第二种方法就简单了，把包含源文件的目录设置成一个全局变量，然后指定读取里面的.c就行了，如：

file(GLOB bzip_c src/main/cpp/bzip2/*.c)

add_library( # Sets the name of the library.
             BsPatchYwl5320

             # Sets the library as a shared library.
             SHARED

             # Provides a relative path to your source file(s).
             ${bzip_c}
             src/main/cpp/bspatch.c
             )

2.2.2、引入动态库BsPatchYwl5320

target_link_libraries( # Specifies the target library.
                       BsPatchYwl5320

                       # Links the target library to the log library
                       # included in the NDK.
                       ${log-lib} )

2.2.3、因为bzip2路径改变了，所以需要修改bspatch.c中#include <bzlib.h> 为 #include "bzip2/bzlib.h"

2.2.4、由于.c中规定只能有一个main方法而bspatch.c中已经有了main方法，所以得查找bzip2中的所有文件中是否含有main方法，如果有就把main方法给改成别的，这里以"文件名_main"的方式更改。

2.2.5、修改好后编译一下，能成功编译则表示源码已经添加配置完成了，如：

三、添加native方法

3.1、编写BsPathYwl5320Util.java类

package com.ywl5320.bspatchywl5320;

/**
 * Created by ywl5320 on 2017/10/25.
 */

public class BsPatchYwl5320Util {

    private static BsPatchYwl5320Util instance = new BsPatchYwl5320Util();

    private BsPatchYwl5320Util(){}

    public static BsPatchYwl5320Util getInstance()
    {
        return instance;
    }

    static
    {
        System.loadLibrary("BsPatchYwl5320");
    }

    public native int bsPatch(String oldfile, String newfile, String patchfile);

}

3.2、编译项目生成.class文件，然后用javah命令生成.h文件

javah com.ywl5320.bspatchywl5320.BsPatchYwl5320Util

3.3.、移动com_ywl5320_bspatchywl5320_BsPatchYwl5320Util.h到cpp文件下，并在bspatch.c中实现native方法，然后添加Android日志打印功能，并修改原来err方法，最终bspatch.c代码如下：

/*-
 * Copyright 2003-2005 Colin Percival
 * All rights reserved
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted providing that the following conditions 
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#if 0
__FBSDID("$FreeBSD: src/usr.bin/bsdiff/bspatch/bspatch.c,v 1.1 2005/08/06 01:59:06 cperciva Exp $");
#endif

#include "com_ywl5320_bspatchywl5320_BsPatchYwl5320Util.h"
#include "bzip2/bzlib.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
//#include <err.h>
#include <unistd.h>
#include <fcntl.h>

//打印日志
#include <android/log.h>
#define LOGI(FORMAT,...) __android_log_print(ANDROID_LOG_INFO,"ywl5320",FORMAT,##__VA_ARGS__);

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 patch_main(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)
    {
        LOGI("usage: %s oldfile newfile patchfile\n",argv[0])
        return 1;
    }
//        errx(1,);

	/* Open patch file */
	if ((f = fopen(argv[3], "r")) == NULL)
    {
        LOGI("can't find patch file: %s", argv[3]);
        return 1;
    }


	/*
	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))
        {
            LOGI("Corrupt patch");
            return 1;
        }
        LOGI("can't read patchfile header: %s", argv[3]);
        return 1;
	}

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

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

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

	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))
    {
        LOGI("can't find oldfile: %s", argv[1]);
        return 1;
    }
	if((new=malloc(newsize+1))==NULL) {
        LOGI("newsize is NULL");
        return 1;
    }

	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))) {
                LOGI("Corrupt patch\n");
                return 1;
            }
			ctrl[i]=offtin(buf);
		};

		/* Sanity-check */
		if(newpos+ctrl[0]>newsize) {
            LOGI("Corrupt patch\n");
            return 1;
        }

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

		/* 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) {
            LOGI("Corrupt patch\n");
            return 1;
        }

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

		/* 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)) {
        LOGI("%s", argv[3]);
        return 1;
    }

	/* 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)) {
        LOGI("can't open newfile: %s", argv[2]);
        return 1;
    }

	free(new);
	free(old);

	return 0;
}

JNIEXPORT jint JNICALL Java_com_ywl5320_bspatchywl5320_BsPatchYwl5320Util_bsPatch(JNIEnv *env, jobject instance, jstring oldfile_,
                                                   jstring newfile_, jstring patchfile_) {

    int restlt = -1;
    int argc = 4;
    char *argv[4];

    const char *oldfile = (*env)->GetStringUTFChars(env, oldfile_, 0);
    const char *newfile = (*env)->GetStringUTFChars(env, newfile_, 0);
    const char *patchfile = (*env)->GetStringUTFChars(env, patchfile_, 0);

    argv[0] = "bspatch_ywl5320";
    argv[1] = oldfile;
    argv[2] = newfile;
    argv[3] = patchfile;
    // TODO
    restlt = patch_main(argc, argv);

    (*env)->ReleaseStringUTFChars(env, oldfile_, oldfile);
    (*env)->ReleaseStringUTFChars(env, newfile_, newfile);
    (*env)->ReleaseStringUTFChars(env, patchfile_, patchfile);

    return restlt;
}

四、测试差分包合并功能

4.1、准备差分包生成的app_patch1.patch包和就app_old1.apk文件，并在手机根目录下创建bspatch文件夹，添加旧文件和差分包到bspatch中：

4.2、在Mainactivity中添加合并代码

package com.ywl5320.bspatchywl5320;

import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Toast;


public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }


    public void onPatch(View view) {

        String oldfile = Environment.getExternalStorageDirectory().getAbsolutePath() + "/bspatch/app_old1.apk";
        String newfile = Environment.getExternalStorageDirectory().getAbsolutePath() + "/bspatch/app_new1.apk";
        String patchfile = Environment.getExternalStorageDirectory().getAbsolutePath() + "/bspatch/app_patch1.patch";

        int restlt = BsPatchYwl5320Util.getInstance().bsPatch(oldfile, newfile, patchfile);
        if(restlt == 0)
        {
            Log.d("ywl5320", "合并成功");
            Toast.makeText(this, "合并成功", Toast.LENGTH_LONG).show();
        }
        else
        {
            Log.d("ywl5320", "合并失败");
            Toast.makeText(this, "合并失败", Toast.LENGTH_LONG).show();
        }
    }
}

4.3、测试合并

最终合并成功，并且可以成功安装。

五、打包.jar文件和提取.so库，方便使用

5.1、打包jar包

jar cvf BsPatchYwl5320Util.jar com\ywl5320\bspatchywl5320\BsPatchYwl5320Util.class

5.2、提取Android全平台.so库

六、总结

至此，增量更新服务端生成差分包、客户端合并差分包都已经完成了。实际开发中可以直接使用差分和合并中生成的jar文件和动态库（dll、so），在客户端请求服务器获取差分包时最好验证旧apk的MD5是否一致，因为Android应用一般都是多渠道的，不然容易出错。还有这里的合并只是测试了功能，具体项目中，是获取本apk的系统目录data中的自己的apk为旧文件，然后再和从服务器下载下来的patch文件合并，并重新安装。

具体实现例子，我会在我的另一个开源项目 AppServiceRestFul 中实现。

源码下载： GitHub BsDiffYwl5320