16.5：引入三方库

笔者在第 4 小节里基于前 3 小结的知识点简单扩展了一个 md5() 方法并成功在 JS 代码里调起了 C++ 代码，本节笔者简单介绍一下引入三方库编译的知识点。

16.5.1：引入MD5源码

上一小节的 md5() 方法实现只是简单模拟，并没有真正实现 MD5 的计算，因此笔者从网上找了一个 MD5 计算的源码并引入工程，工程目录如下所示：

其中 md5.h 源码如下所示：

//
// Created on 2023/2/28.
//
// Node APIs are not fully supported. To solve the compilation error of the interface cannot be found,
// please include "napi/native_api.h".

#ifndef oh_0400_napi_md5_H
#define oh_0400_napi_md5_H

/* Parameters of MD5. */
#define s11 7
#define s12 12
#define s13 17
#define s14 22

#define s21 5
#define s22 9
#define s23 14
#define s24 20

#define s31 4
#define s32 11
#define s33 16
#define s34 23

#define s41 6
#define s42 10
#define s43 15
#define s44 21

#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))

#define ROTATELEFT(num, n) (((num) << (n)) | ((num) >> (32-(n))))

#define FF(a, b, c, d, x, s, ac) { \
  (a) += F ((b), (c), (d)) + (x) + ac; \
  (a) = ROTATELEFT ((a), (s)); \
  (a) += (b); \
}
#define GG(a, b, c, d, x, s, ac) { \
  (a) += G ((b), (c), (d)) + (x) + ac; \
  (a) = ROTATELEFT ((a), (s)); \
  (a) += (b); \
}
#define HH(a, b, c, d, x, s, ac) { \
  (a) += H ((b), (c), (d)) + (x) + ac; \
  (a) = ROTATELEFT ((a), (s)); \
  (a) += (b); \
}
#define II(a, b, c, d, x, s, ac) { \
  (a) += I ((b), (c), (d)) + (x) + ac; \
  (a) = ROTATELEFT ((a), (s)); \
  (a) += (b); \
}

#include <string>
#include <cstring>

using std::string;

/* Define of btye.*/
typedef unsigned char byte;
/* Define of byte. */
typedef unsigned int bit32;

class MD5 {
public:
    /* Construct a MD5 object with a string. */
    MD5(const string& message);

    /* Generate md5 digest. */
    const byte* getDigest();

    /* Convert digest to string value */
    string toStr();

private:
    /* Initialization the md5 object, processing another message block,
     * and updating the context.*/
    void init(const byte* input, size_t len);

    /* MD5 basic transformation. Transforms state based on block. */
    void transform(const byte block[64]);

    /* Encodes input (usigned long) into output (byte). */
    void encode(const bit32* input, byte* output, size_t length);

    /* Decodes input (byte) into output (usigned long). */
    void decode(const byte* input, bit32* output, size_t length);

private:
    /* Flag for mark whether calculate finished. */
    bool finished;

    /* state (ABCD). */
    bit32 state[4];

    /* number of bits, low-order word first. */
    bit32 count[2];

    /* input buffer. */
    byte buffer[64];

    /* message digest. */
    byte digest[16];

    /* padding for calculate. */
    static const byte PADDING[64];

    /* Hex numbers. */
    static const char HEX_NUMBERS[16];
};

#endif //oh_0400_napi_md5_H

md5.cpp 源码如下所示：

//
// Created on 2023/2/28.
//
// Node APIs are not fully supported. To solve the compilation error of the interface cannot be found,
// please include "napi/native_api.h".

#include "md5.h"
#include <string>

/* Define the static member of MD5. */
const byte MD5::PADDING[64] = { 0x80 };
const char MD5::HEX_NUMBERS[16] = {
        '0', '1', '2', '3',
        '4', '5', '6', '7',
        '8', '9', 'a', 'b',
        'c', 'd', 'e', 'f'
};

MD5::MD5(const string& message) {
    finished = false;
    /* Reset number of bits. */
    count[0] = count[1] = 0;

    /* Initialization constants. */
    state[0] = 0x67452301;
    state[1] = 0xefcdab89;
    state[2] = 0x98badcfe;
    state[3] = 0x10325476;
    
    /* Initialization the object according to message. */
    init((const byte*)message.c_str(), message.length());
}

/**
 * @Generate md5 digest.
 *
 * @return the message-digest.
 *
 */
const byte* MD5::getDigest() {
    if (!finished) {
        finished = true;

        byte bits[8];
        bit32 oldState[4];
        bit32 oldCount[2];
        bit32 index, padLen;

        /* Save current state and count. */
        memcpy(oldState, state, 16);
        memcpy(oldCount, count, 8);

        /* Save number of bits */
        encode(count, bits, 8);

        /* Pad out to 56 mod 64. */
        index = (bit32)((count[0] >> 3) & 0x3f);
        padLen = (index < 56) ? (56 - index) : (120 - index);
        init(PADDING, padLen);

        /* Append length (before padding) */
        init(bits, 8);

        /* Store state in digest */
        encode(state, digest, 16);

        /* Restore current state and count. */
        memcpy(state, oldState, 16);
        memcpy(count, oldCount, 8);
    }
    return digest;
}

/**
 * @Initialization the md5 object, processing another message block,
 * and updating the context.
 *
 * @param {input} the input message.
 *
 * @param {len} the number btye of message.
 *
 */
void MD5::init(const byte* input, size_t len) {

    bit32 i, index, partLen;

    finished = false;

    /* Compute number of bytes mod 64 */
    index = (bit32)((count[0] >> 3) & 0x3f);

    /* update number of bits */
    if ((count[0] += ((bit32)len << 3)) < ((bit32)len << 3)) {
        ++count[1];
    }
    count[1] += ((bit32)len >> 29);

    partLen = 64 - index;

    /* transform as many times as possible. */
    if (len >= partLen) {

        memcpy(&buffer[index], input, partLen);
        transform(buffer);

        for (i = partLen; i + 63 < len; i += 64) {
            transform(&input[i]);
        }
        index = 0;

    } else {
        i = 0;
    }

    /* Buffer remaining input */
    memcpy(&buffer[index], &input[i], len - i);
}


void MD5::transform(const byte block[64]) {

    bit32 a = state[0], b = state[1], c = state[2], d = state[3], x[16];

    decode(block, x, 64);

    /* Round 1 */
    FF (a, b, c, d, x[ 0], s11, 0xd76aa478);
    FF (d, a, b, c, x[ 1], s12, 0xe8c7b756);
    FF (c, d, a, b, x[ 2], s13, 0x242070db);
    FF (b, c, d, a, x[ 3], s14, 0xc1bdceee);
    FF (a, b, c, d, x[ 4], s11, 0xf57c0faf);
    FF (d, a, b, c, x[ 5], s12, 0x4787c62a);
    FF (c, d, a, b, x[ 6], s13, 0xa8304613);
    FF (b, c, d, a, x[ 7], s14, 0xfd469501);
    FF (a, b, c, d, x[ 8], s11, 0x698098d8);
    FF (d, a, b, c, x[ 9], s12, 0x8b44f7af);
    FF (c, d, a, b, x[10], s13, 0xffff5bb1);
    FF (b, c, d, a, x[11], s14, 0x895cd7be);
    FF (a, b, c, d, x[12], s11, 0x6b901122);
    FF (d, a, b, c, x[13], s12, 0xfd987193);
    FF (c, d, a, b, x[14], s13, 0xa679438e);
    FF (b, c, d, a, x[15], s14, 0x49b40821);

    /* Round 2 */
    GG (a, b, c, d, x[ 1], s21, 0xf61e2562);
    GG (d, a, b, c, x[ 6], s22, 0xc040b340);
    GG (c, d, a, b, x[11], s23, 0x265e5a51);
    GG (b, c, d, a, x[ 0], s24, 0xe9b6c7aa);
    GG (a, b, c, d, x[ 5], s21, 0xd62f105d);
    GG (d, a, b, c, x[10], s22,  0x2441453);
    GG (c, d, a, b, x[15], s23, 0xd8a1e681);
    GG (b, c, d, a, x[ 4], s24, 0xe7d3fbc8);
    GG (a, b, c, d, x[ 9], s21, 0x21e1cde6);
    GG (d, a, b, c, x[14], s22, 0xc33707d6);
    GG (c, d, a, b, x[ 3], s23, 0xf4d50d87);
    GG (b, c, d, a, x[ 8], s24, 0x455a14ed);
    GG (a, b, c, d, x[13], s21, 0xa9e3e905);
    GG (d, a, b, c, x[ 2], s22, 0xfcefa3f8);
    GG (c, d, a, b, x[ 7], s23, 0x676f02d9);
    GG (b, c, d, a, x[12], s24, 0x8d2a4c8a);

    /* Round 3 */
    HH (a, b, c, d, x[ 5], s31, 0xfffa3942);
    HH (d, a, b, c, x[ 8], s32, 0x8771f681);
    HH (c, d, a, b, x[11], s33, 0x6d9d6122);
    HH (b, c, d, a, x[14], s34, 0xfde5380c);
    HH (a, b, c, d, x[ 1], s31, 0xa4beea44);
    HH (d, a, b, c, x[ 4], s32, 0x4bdecfa9);
    HH (c, d, a, b, x[ 7], s33, 0xf6bb4b60);
    HH (b, c, d, a, x[10], s34, 0xbebfbc70);
    HH (a, b, c, d, x[13], s31, 0x289b7ec6);
    HH (d, a, b, c, x[ 0], s32, 0xeaa127fa);
    HH (c, d, a, b, x[ 3], s33, 0xd4ef3085);
    HH (b, c, d, a, x[ 6], s34,  0x4881d05);
    HH (a, b, c, d, x[ 9], s31, 0xd9d4d039);
    HH (d, a, b, c, x[12], s32, 0xe6db99e5);
    HH (c, d, a, b, x[15], s33, 0x1fa27cf8);
    HH (b, c, d, a, x[ 2], s34, 0xc4ac5665);

    /* Round 4 */
    II (a, b, c, d, x[ 0], s41, 0xf4292244);
    II (d, a, b, c, x[ 7], s42, 0x432aff97);
    II (c, d, a, b, x[14], s43, 0xab9423a7);
    II (b, c, d, a, x[ 5], s44, 0xfc93a039);
    II (a, b, c, d, x[12], s41, 0x655b59c3);
    II (d, a, b, c, x[ 3], s42, 0x8f0ccc92);
    II (c, d, a, b, x[10], s43, 0xffeff47d);
    II (b, c, d, a, x[ 1], s44, 0x85845dd1);
    II (a, b, c, d, x[ 8], s41, 0x6fa87e4f);
    II (d, a, b, c, x[15], s42, 0xfe2ce6e0);
    II (c, d, a, b, x[ 6], s43, 0xa3014314);
    II (b, c, d, a, x[13], s44, 0x4e0811a1);
    II (a, b, c, d, x[ 4], s41, 0xf7537e82);
    II (d, a, b, c, x[11], s42, 0xbd3af235);
    II (c, d, a, b, x[ 2], s43, 0x2ad7d2bb);
    II (b, c, d, a, x[ 9], s44, 0xeb86d391);

    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;
}

/**
* @Encodes input (unsigned long) into output (byte).
*
* @param {input} usigned long.
*
* @param {output} byte.
*
* @param {length} the length of input.
*
*/
void MD5::encode(const bit32* input, byte* output, size_t length) {

    for (size_t i = 0, j = 0; j < length; ++i, j += 4) {
        output[j]= (byte)(input[i] & 0xff);
        output[j + 1] = (byte)((input[i] >> 8) & 0xff);
        output[j + 2] = (byte)((input[i] >> 16) & 0xff);
        output[j + 3] = (byte)((input[i] >> 24) & 0xff);
    }
}

/**
 * @Decodes input (byte) into output (usigned long).
 *
 * @param {input} bytes.
 *
 * @param {output} unsigned long.
 *
 * @param {length} the length of input.
 *
 */
void MD5::decode(const byte* input, bit32* output, size_t length) {
    for (size_t i = 0, j = 0; j < length; ++i, j += 4) {
        output[i] = ((bit32)input[j]) | (((bit32)input[j + 1]) << 8) |
                    (((bit32)input[j + 2]) << 16) | (((bit32)input[j + 3]) << 24);
    }
}


/**
 * @Convert digest to string value.
 *
 * @return the hex string of digest.
 *
 */
string MD5::toStr() {
    const byte* digest_ = getDigest();
    string str;
    str.reserve(16 << 1);
    for (size_t i = 0; i < 16; ++i) {
        int t = digest_[i];
        int a = t / 16;
        int b = t % 16;
        str.append(1, HEX_NUMBERS[a]);
        str.append(1, HEX_NUMBERS[b]);
    }
    return str;
}

16.5.2：使用MD5算法

引入 MD5 算法后，就可以在 hello.cpp 里的 Md5() 方法内实现 MD5 算法了，使用流程如下：

• 引入头文件

  引入头文件的目的是调用其提供的 MD5 计算方法，和 JS 里的 import 功能类似。

  #include "./md5/md5.h"
  

• 使用md5算法

  修改 hello.cpp 里的 Md5() 方法内容如下所示：

  static napi_value Md5(napi_env env, napi_callback_info info) {
      // 1、从info中取出JS传递过来的参数放入args
      size_t argc = 1;
      napi_value args[1] = { nullptr };
      if (napi_ok != napi_get_cb_info(env, info, &argc, args, nullptr, nullptr)) {
          napi_throw_error(env, "-1000", "napi_get_cb_info error");
          return nullptr;
      }
  
      // 2、获取参数的类型
      napi_valuetype stringType;
      if (napi_ok != napi_typeof(env, args[0], &stringType)) {
          napi_throw_error(env, "-1001", "napi_typeof error");
          return nullptr;
      }
  
      // 3、如果参数为null，这抛异常
      if (napi_null == stringType) {
          napi_throw_error(env, "-1002", "the param can't be null");
          return nullptr;
      }
  
      // 4、获取传递的string长度
      size_t length = 0;
      if (napi_ok != napi_get_value_string_utf8(env, args[0], nullptr, 0, &length)) {
          napi_throw_error(env, "-1003", "napi_get_value_string_utf8 error");
          return nullptr;
      }
  
      // 5、如果传递的是""，则抛异常
      if (length == 0) {
          napi_throw_error(env, "-1004", "the param length invalid");
          return nullptr;
      }
  
      // 6、读取传递的string参数放入buffer中
      char* buffer = new char[length + 1];
      if (napi_ok != napi_get_value_string_utf8(env, args[0], buffer, length + 1, &length)) {
          delete[] buffer;
          buffer = nullptr;
          napi_throw_error(env, "-1005", "napi_get_value_string_utf8 error");
          return nullptr;
      }
  
    
    
      // **********************************************************************
      // ********************************MD5加密********************************
      // 7、计算MD5加密操作
      std::string str = buffer;
      // MD5 加密计算
      str = MD5(str).toStr();
      // **********************************************************************
      // ********************************MD5加密********************************
  
    
    
      // 8、把C++数据转成napi_value并返回
      napi_value value = nullptr;
      const char* md5 = str.c_str();
      if (napi_ok != napi_create_string_utf8(env, md5, strlen(md5), &value)) {
          delete[] buffer;
          buffer = nullptr;
          napi_throw_error(env, "-1006", "napi_create_string_utf8 error");
          return nullptr;
      }
  
      // 9、资源清理
      delete[] buffer;
      buffer = nullptr;
  
      return value;
  }
  

  主要看第 7 步：直接创建 MD5 后调用其 toStr() 方法即可生成加密后的字符串。

16.5.3：修改CMake文件

增加了 MD5 计算的源码，需要修改 CMakeLists.txt 文件，目的是把计算 MD5 的源文件打包进 so 中，修改后的代码如下所示：

# the minimum version of CMake.
cmake_minimum_required(VERSION 3.4.1)
project(oh_0400_napi)

set(NATIVERENDER_ROOT_PATH ${CMAKE_CURRENT_SOURCE_DIR})

include_directories(${NATIVERENDER_ROOT_PATH}
                    ${NATIVERENDER_ROOT_PATH}/include)

# 把 md5.cpp 源文件引入
add_library(entry SHARED hello.cpp ./md5/md5.cpp)

target_link_libraries(entry PUBLIC libace_napi.z.so)

16.5.4：测试MD5算法

根据 Md5() 方法的实现，限制条件是不允许数据 null 和 ""，如果输入则抛异常。因此可测试以下三种场景：正常参数，null 参数和 "" 参数，样例代码如下所示：

import testNapi from 'libentry.so'

@Entry @Component struct Index {

  @State message: string = 'Hello，OpenHarmony'

  build() {
    Column({space: 10}) {

      Text(this.message)
        .fontSize(20)

      Button("正常参数")
        .onClick(() => {
          this.message = testNapi.md5("Hello, OpenHarmony")
        })

      Button("null参数")
        .onClick(() => {
          this.message = testNapi.md5(null);
        })

      Button("\"\"参数")
        .onClick(() => {
          this.message = testNapi.md5("");
        })
    }
    .padding(10)
    .width('100%')
    .height("100%")
  }
}

点解 正常参数 按钮，输出结果和在线网站上计算的结果一致，非常棒(#^.^#)，样例运行结果如下所示：

16.5.5：小结

本节笔者通过引入三方库的方式实现了 MD5 的计算，当前只是一个简单的计算，如果是一个非常复杂的耗时计算，就会阻塞主线程，因此需要实现异步方法，笔者将要在下节讲解一下异步的实现方式。