修改aapt和自定义资源ID

本文修改的aapt的源码为Android 6.0.0_r1版本

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本文中的aapt源码查看和修改参照Android中如何修改编译的资源ID值(默认值是0x7F…可以随意改成0x02~0x7E)和Android aapt实现资源分区（补充携程aapt源码）这两篇博客。本文主要是记录修改过程和编译aapt模块的命令。

源码查看

aapt的源码在所在的目录：Android/frameworks/base/tools/aapt/。

Main.cpp位置：android-6.0.0_r1/frameworks/base/tools/aapt/Main.cpp
首先查看Main.cpp的main方法:

int main(int argc, char* const argv[]){    char *prog = argv[0];    Bundle bundle;    bool wantUsage = false;    int result = 1;    // pessimistically assume an error.    ...    //进行资源打包的参数p或package    else if (argv[1][0] == 'p')        bundle.setCommand(kCommandPackage);    ...    /*     * Pull out flags.  We support "-fv" and "-f -v".     */    while (argc && argv[0][0] == '-') {        /* flag(s) found */        const char* cp = argv[0] +1;        while (*cp != '\0') {            ...            //收集appt命令输入的参数，这些参数以"-"开头            case '-':                if (strcmp(cp, "-debug-mode") == 0) {                    bundle.setDebugMode(true);                }             ...                break;            default:                fprintf(stderr, "ERROR: Unknown flag '-%c'\n", *cp);                wantUsage = true;                goto bail;            }            cp++;        }        argc--;        argv++;    }    /*     * We're past the flags.  The rest all goes straight in.     */    bundle.setFileSpec(argv, argc);    //根据bundle收集的参数进行资源处理    result = handleCommand(&bundle);//输入参数错误时会跳转到此bail:    if (wantUsage) {        usage();        result = 2;    }    return result;}

在main函数内，首先创建一个Bundle对象，这个对象用来存储输入的操作类型和相关的参数。argv相当于java中的字符串数组。取该数组的第2个字符串的第一个char值。因为是执行资源打包，所以它是’p’。bundle记录执行类型为kCommandPackage，即资源打包。while循环处理剩余的char数组（即字符串数组），将参数按照类型设置到bundle中。参数解析完毕，则会执行handleCommand(&bundle)。如果在解析输入的参数时出现了错误，便使用goto跳转到bail代码块。在bail代码块中可能会执行usage();，这个方法会打印出aapt所有的命令类型和相关的参数。

先看看usage()函数，省略了与资源打包无关的信息。

void usage(void){    ...    fprintf(stderr,        " %s p[ackage] [-d][-f][-m][-u][-v][-x][-z][-M AndroidManifest.xml] \\\n"        "        [-0 extension [-0 extension ...]] [-g tolerance] [-j jarfile] \\\n"        "        [--debug-mode] [--min-sdk-version VAL] [--target-sdk-version VAL] \\\n"        "        [--app-version VAL] [--app-version-name TEXT] [--custom-package VAL] \\\n"        "        [--rename-manifest-package PACKAGE] \\\n"        "        [--rename-instrumentation-target-package PACKAGE] \\\n"        "        [--utf16] [--auto-add-overlay] \\\n"        "        [--max-res-version VAL] \\\n"        "        [-I base-package [-I base-package ...]] \\\n"        "        [-A asset-source-dir]  [-G class-list-file] [-P public-definitions-file] \\\n"        "        [-S resource-sources [-S resource-sources ...]] \\\n"        "        [-F apk-file] [-J R-file-dir] \\\n"        "        [--product product1,product2,...] \\\n"        "        [-c CONFIGS] [--preferred-density DENSITY] \\\n"        "        [--split CONFIGS [--split CONFIGS]] \\\n"        "        [--feature-of package [--feature-after package]] \\\n"        "        [raw-files-dir [raw-files-dir] ...] \\\n"        "        [--output-text-symbols DIR]\n"        "        [--apk-module moduleName]\n"        "\n"        "   Package the android resources.  It will read assets and resources that are\n"        "   supplied with the -M -A -S or raw-files-dir arguments.  The -J -P -F and -R\n"        "   options control which files are output.\n\n"        , gProgName);        ...}

打印appt执行的操作类型和对应的参数。

先看看handleCommand()函数，

int handleCommand(Bundle* bundle){    switch (bundle->getCommand()) {    case kCommandVersion:      return doVersion(bundle);    ...    case kCommandPackage:      return doPackage(bundle);    ...    default:        fprintf(stderr, "%s: requested command not yet supported\n", gProgName);        return 1;    }}

在main函数中bundle设置的cmmand类型为kCommandPackage，所以会执行doPackage(bundle)代码。使用操作系统自带的搜索，检索aapt目录内的文件内容’doPackage’。会查找到doPackage()是Command.cpp中的函数。

Command.cpp位置：android-6.0.0_r1/frameworks/base/tools/aapt/Command.cpp
doPackage()函数中处理资源相关的代码：

int doPackage(Bundle* bundle){    ...    // If they asked for any fileAs that need to be compiled, do so.    if (bundle->getResourceSourceDirs().size() || bundle->getAndroidManifestFile()) {        err = buildResources(bundle, assets, builder);        if (err != 0) {            goto bail;        }    }    ...}

继续搜索buildResources()函数所在的文件，查找到Resource.cpp。

Resource.cpp位置：android-6.0.0_r1/frameworks/base/tools/aapt/Resource.cpp
buildResources()函数中创建资源表相关的代码：

status_t buildResources(Bundle* bundle, const sp<AaptAssets>& assets, sp<ApkBuilder>& builder){    ...    //设置资源类型    ResourceTable::PackageType packageType = ResourceTable::App;    if (bundle->getBuildSharedLibrary()) {        packageType = ResourceTable::SharedLibrary;    } else if (bundle->getExtending()) {        packageType = ResourceTable::System;    } else if (!bundle->getFeatureOfPackage().isEmpty()) {        packageType = ResourceTable::AppFeature;    }    //创建资源表    ResourceTable table(bundle, String16(assets->getPackage()), packageType);    ...}

继续查看ResourceTable.cpp的构造函数。

ResourceTable.cpp位置：android-6.0.0_r1/frameworks/base/tools/aapt/ResourceTable.cpp
ResourceTable构造函数

ResourceTable::ResourceTable(Bundle* bundle, const String16& assetsPackage, ResourceTable::PackageType type)    : mAssetsPackage(assetsPackage)    , mPackageType(type)    , mTypeIdOffset(0)    , mNumLocal(0)    , mBundle(bundle){    ssize_t packageId = -1;    switch (mPackageType) {        case App:        case AppFeature:            packageId = 0x7f;            break;        case System:            packageId = 0x01;            break;        case SharedLibrary:            packageId = 0x00;            break;        default:            assert(0);            break;    }    sp<Package> package = new Package(mAssetsPackage, packageId);    mPackages.add(assetsPackage, package);    mOrderedPackages.add(package);    // Every resource table always has one first entry, the bag attributes.    const SourcePos unknown(String8("????"), 0);    getType(mAssetsPackage, String16("attr"), unknown);}

应用的资源id从0x7f开始，系统的资源id从0x01开始，共享类库的从0x00开始。如果我们想要自定义应用的资源id的起始值，则需要在switch结束后重新设置packageId值。这个自定义值可以Main.cpp的main函数中解析获取，并存放到bundle中。

修改源码

1，修改Bundle.h文件。
Bundle.h位置：android-6.0.0_r1/frameworks/base/tools/aapt/Bundle.h

添加如下代码：

class Bundle {public:    ...    //添加的获取和设置自定义id的函数    const android::String8& getApkModule() const {return mApkModule;}    void setApkModule(const char* str) { mApkModule=str;}    ...private:    /* commands & modifiers */    ...    //自定义id    android::String8 mApkModule;    ...}

2，修改Main.cpp的main函数，添加解析自定义id的参数并设置到bundle。
代码如下：

int main(int argc, char* const argv[]){    ...    while (argc && argv[0][0] == '-') {        ...        while (*cp != '\0') {            ...            case '-':                ...                //添加解析-apk-module参数信息                } else if(strcmp(cp, "-apk-module") == 0){                    argc--;                    argv++;                    if (!argc) {                        fprintf(stderr, "ERROR: No argument supplied for '--apk-model' option\n");                         wantUsage = true;                         goto bail;                    }                    bundle.setApkModule(argv[0]);                } else if (strcmp(cp, "-feature-of") == 0) {                ...                break;            ...        }        ...    }    ...}

3，修改ResourceTable.cpp的构造函数，添加判断是否存在自定义id，如果存在，则修改packageId为自定义id。

ResourceTable::ResourceTable(Bundle* bundle, const String16& assetsPackage, ResourceTable::PackageType type)    ...{    ssize_t packageId = -1;    switch (mPackageType) {        ...    }    //判断和设置自定义id    if(!bundle->getApkModule().isEmpty()){        android::String8 apkModuleVal = bundle->getApkModule();        packageId = apkStringToInt(apkModuleVal);    }    sp<Package> package = new Package(mAssetsPackage, packageId);    ...}//将字符串转换为ssize_t类型ssize_t ResourceTable::apkStringToInt(const String8& s){    size_t i = 0;    ssize_t val = 0;    size_t len=s.length();    if (s[i] < '0' || s[i] > '9') {        return -1;    }    // Decimal or hex?    if (s[i] == '0' && s[i+1] == 'x') {        i += 2;        bool error = false;        while (i < len && !error) {            val = (val*16) + apkgetHex(s[i], &error);            i++;        }        if (error) {            return -1;        }    } else {        while (i < len) {            if (s[i] < '0' || s[i] > '9') {                return false;            }            val = (val*10) + s[i]-'0';            i++;        }    }    if (i == len) {        return val;    }    return -1;}//转换为16进制uint32_t ResourceTable::apkgetHex(char c, bool* outError){    if (c >= '0' && c <= '9') {        return c - '0';    } else if (c >= 'a' && c <= 'f') {        return c - 'a' + 0xa;    } else if (c >= 'A' && c <= 'F') {        return c - 'A' + 0xa;    }    *outError = true;    return 0;}

还需要在ResourceTable.h文件中声明apkStringToInt()和apkgetHex()函数。
ResourceTable.h位置：android-6.0.0_r1/frameworks/base/tools/aapt/ResourceTable.h
添加到public或private中。

    ssize_t apkStringToInt(const String8& s);    uint32_t apkgetHex(char c, bool* outError);

编译和修改错误

修改完毕，开启终端（或控制台）进入到android-6.0.0_r1目录，运行. build/envsetup.sh命令，配置运行环境。配置命令运行完毕，运行cd frameworks/base/tools/aapt，进入到aapt目录。执行mm命令，该命令会编译aapt模块中的代码，并生成可执行文件。运行结果如下：

============================================PLATFORM_VERSION_CODENAME=RELPLATFORM_VERSION=6.0TARGET_PRODUCT=fullTARGET_BUILD_VARIANT=engTARGET_BUILD_TYPE=releaseTARGET_BUILD_APPS=TARGET_ARCH=armTARGET_ARCH_VARIANT=armv7-aTARGET_CPU_VARIANT=genericTARGET_2ND_ARCH=TARGET_2ND_ARCH_VARIANT=TARGET_2ND_CPU_VARIANT=HOST_ARCH=x86_64HOST_OS=darwinHOST_OS_EXTRA=Darwin-16.0.0-x86_64-i386-64bitHOST_BUILD_TYPE=releaseBUILD_ID=MRA58KOUT_DIR=out============================================host C++: aapt <= frameworks/base/tools/aapt/Main.cpphost Executable: aapt (out/host/darwin-x86/obj/EXECUTABLES/aapt_intermediates/aapt)clang: warning: argument unused during compilation: '-pie'Install: out/host/darwin-x86/bin/aapt\e[0;32m#### make completed successfully (3 seconds) ####\e[00m

生产的文件为aapt，在’android-6.0.0_r1/out/host/darwin-x86/bin/’目录中。
将aapt拷贝到指定目录，进入PluginDemo工程目录，使用aapt对工程进行资源打包，执行的命令如下：

../../../devTools/aapt/aapt package -f -m --apk-module 0x8f -J gen -S res -M AndroidManifest.xml -I ../../../devTools/android/android-sdk-macosx/platforms/android-23/android.jar -F build/out/res.ap_

该命令执行失败，某个资源id找不到对应的资源。错误信息：

res/layout/xxx.xml:9: error: Error: No resource found that matches the given name (at 'text' with value '@string/xxx').

搜索相关的博客，在区长的专栏的Android aapt实现资源分区（补充携程aapt源码）这篇博客找到了出错的原因和解决方法。

继续看代码，

bool ResTable::stringToValue(Res_value* outValue, String16* outString,                             const char16_t* s, size_t len,                             bool preserveSpaces, bool coerceType,                             uint32_t attrID,                             const String16* defType,                             const String16* defPackage,                             Accessor* accessor,                             void* accessorCookie,                             uint32_t attrType,                             bool enforcePrivate) const{    ...    if (*s == '@') {            if (accessor) {                uint32_t rid = accessor->getCustomResourceWithCreation(package, type, name,                                                                       createIfNotFound);                if (rid != 0) {                    if (kDebugTableNoisy) {                        ALOGI("Pckg %s:%s/%s: 0x%08x\n",                                String8(package).string(), String8(type).string(),                                String8(name).string(), rid);                    }                    uint32_t packageId = Res_GETPACKAGE(rid) + 1;                    if (packageId == 0x00) {                        outValue->data = rid;                        outValue->dataType = Res_value::TYPE_DYNAMIC_REFERENCE;                        return true;                    } else if (packageId == APP_PACKAGE_ID || packageId == SYS_PACKAGE_ID ) {                        // We accept packageId's generated as 0x01 in order to support                        // building the android system resources                        outValue->data = rid;                        return true;                    }                }            }        }        if (accessor != NULL) {            accessor->reportError(accessorCookie, "No resource found that matches the given name");        }        return false;    }    ...}

在if(accessor)代码中对packageId进行验证。如果packageId不是ResourceTable构造函数中设置的3种类型，则出错，无法生成R.java文件和资源包。需要将ResourceTable构造函数中设置的packageId值存储下来，并在if (packageId == APP_PACKAGE_ID || packageId == SYS_PACKAGE_ID )添加一个自定义id判断。

按照区长的博客添加头文件和cpp文件，并添加相应的代码。具体的代码请查看Android aapt实现资源分区（补充携程aapt源码）博客，本文不再写出。
1，创建文件
创建Help.h文件，存放在android-6.0.0_r1/frameworks/base/include/androidfw/。
创建Help.cpp文件，存放在android-6.0.0_r1/frameworks/base/libs/androidfw/。并将Help.cpp添加到android-6.0.0_r1/frameworks/base/libs/androidfw/Android.mk文件。
2，修改代码
在ResourceTable::ResourceTable()函数判断和设置自定义id代码后面添加使用Help记录packageId代码。
在ResTable::stringToValue()函数中添加对Help中记录的packageId判断代码。

重新编译aapt模块，获取新生成的aapt可执行文件。再次运行生成R.java和资源打包命令（与之前的命令相同），成功运行。

生成的R.java文件内容

package com.plugin.test;public final class R {    public static final class attr {    }    public static final class drawable {        public static final int p_icon_play=0x8f020000;    }    public static final class id {        public static final int activity_main=0x8f070000;    }    public static final class layout {        public static final int plugin_item=0x8f040000;    }    public static final class mipmap {        public static final int p_icon_lock=0x8f030000;    }    public static final class string {        public static final int app_name=0x8f050000;        public static final int p_str=0x8f050001;    }    public static final class style {        public static final int AppBaseTheme=0x8f060000;        public static final int AppTheme=0x8f060001;    }}

不再是原来系统默认的0x7f，都是自定义的0x8f。

继续执行命令编译代码，将class转换为dex，并将dex和资源包合并生成的apk。对apk签名，运行apk。apk正常运行，截图如下。