使用android的ndk学习c++的stl库

- 日理万妓 2022-05-16 20:39 274阅读 0赞

1、创建android工程，ndk工具类，生成头文件

activity代码：

public class MainActivity extends AppCompatActivity  implements View.OnClickListener {
        private TextView tv;
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            tv=findViewById(R.id.sample_text);
            tv.setOnClickListener(this);
        }
        @Override
        public void onClick(View v) {
            switch (v.getId()){
                case R.id.sample_text:
                     StlUtils.stlApply();
                    break;
            }
        }
    }

ndk工具类的StlUtils

public class StlUtils {
        static {
            System.loadLibrary("stlib");
        }
        public static  native  void  stlApply();
    }

生成头文件

#include <jni.h>
    /* Header for class dh_fcw_cn_myapplication_StlUtils */
    #ifndef _Included_dh_fcw_cn_myapplication_StlUtils
    #define _Included_dh_fcw_cn_myapplication_StlUtils
    #ifdef __cplusplus
    extern "C" {
    #endif
    /*
     * Class:     dh_fcw_cn_myapplication_StlUtils
     * Method:    stlApply
     * Signature: ()V
     */
    JNIEXPORT void JNICALL Java_dh_fcw_cn_myapplication_StlUtils_stlApply
      (JNIEnv *, jclass);
    
    #ifdef __cplusplus
    }
    #endif
    #endif

二、配置Cmake编译

创建CMakeLists文件

cmake_minimum_required(VERSION 3.4.1）
    add_library( stlib  SHARED src/main/jni/stlib.cpp )
    find_library( log-lib  log )
    target_link_libraries( stlib  ${log-lib} )

buildgradle配置

defaultConfig {
            applicationId "dh.fcw.cn.myapplication"
            minSdkVersion 15
            targetSdkVersion 27
            versionCode 1
            versionName "1.0"
            testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
            ndk{
                 abiFilters("armeabi-v7a","x86")
                 ldLibs("android","log")
                 stl="stlport_static"
            }
            externalNativeBuild {
                cmake { cppFlags "-std=c++14"}
            }
        }
        externalNativeBuild {
            cmake {
                path "CMakeLists.txt"
            }
        }
        buildTypes {
            release {
                minifyEnabled false
                proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
            }
        }

3.编写c++代码

在jni 文件夹下创建stlib.cp

#include "dh_fcw_cn_myapplication_StlUtils.h"
    #include <jni.h>
    #include <vector>
    #include <string.h>
    #include <iostream>
    #include <stdio.h>
    #include <stdlib.h>
    #include <time.h>
    #include <android/log.h>
    #define random(x) (rand()%x)
    #define TAG "MyLog"
    #define LOGI(...)  __android_log_print(ANDROID_LOG_INFO,TAG,__VA_ARGS__)
    #define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG, TAG, __VA_ARGS__)
    #define LOGE(...) __android_log_print(ANDROID_LOG_ERROR,TAG,__VA_ARGS__)
    using namespace std;
    
    class  Student{
       public:
        Student(){}
        ~Student(){}
        string  name;
        int    age;
        string address;
        int    index;
        void printStuInfo(){
            LOGI("姓名=%s,年齡=%d,地址=%s,序號=%d",name.c_str(),age,address.c_str(),index);
        }
    };
    
    typedef struct   Person{
        char*  name;
        int    age;
        char*  address;
        int    index;
    
    } Per;
    
    void printPersonInfo( Per* p){
        char* name=p->name;
        int age=p->age;
        char* address=p->address;
        int index=p->index;
        LOGI("姓名=%s,年齡=%d,地址=%s,序號=%d",name,age,address,index);
    }
    
    JNIEXPORT void JNICALL Java_dh_fcw_cn_myapplication_StlUtils_stlApply(JNIEnv * jniEnv, jclass obj){
        try {
            vector<string>  list;
            string str="ABCDEFGLHGKLMNOPQRSTUVWXYZ";
            for(int i=0;i<10;i++){
                srand(static_cast<unsigned int>((int)time(0)));
                int start=random(15);
                string t= str.substr(start,25);
                list.push_back(t);
            }
    
            for(int i=0;i<list.size();i++){
                string  r=list[i];
                LOGI("r=%s",r.c_str());
            }
        }catch (const char* msg ){
           LOGE("ERR=%s",msg);
        }
    
    
        try {
            vector<Student>  listStu;
            for(int i=0;i<10;i++){
                Student stu1;
                stu1.name="劉翠";
                stu1.age=i*3;
                stu1.address="河南開封蘭考";
                stu1.index=i;
                listStu.push_back(stu1);
            }
    
            for(int i=0;i<listStu.size();i++){
                Student  s=listStu[i];
                s.printStuInfo();
            }
        }catch (const char* msg ){
            LOGE("ERR=%s",msg);
        }
    
    
        try {
            vector<Per>  listPerson;
            for(int i=0;i<10;i++){
                Per *p=NULL;
                Per  per;
                p=&per;
                p->name="刘萍";
                p->address="河南信阳新县";
                p->index=i;
                p->age=i*4;
                listPerson.push_back(per);
            }
    
            for(int i=0;i<listPerson.size();i++){
                   Per per=listPerson[i];
                   Per* p=NULL;
                   p=&per;
                   printPersonInfo(p);
            }
        }catch (const char* msg ){
            LOGE("ERR=%s",msg);
        }
    
    
    }

运行结果：

08-08 20:01:48.237 3795-3795/dh.fcw.cn.myapplication I/MyLog: r=LHGKLMNOPQRSTUVWXYZ
    08-08 20:01:48.238 3795-3795/dh.fcw.cn.myapplication I/MyLog: r=LHGKLMNOPQRSTUVWXYZ
        r=LHGKLMNOPQRSTUVWXYZ
        r=LHGKLMNOPQRSTUVWXYZ
        r=LHGKLMNOPQRSTUVWXYZ
        r=LHGKLMNOPQRSTUVWXYZ
        r=LHGKLMNOPQRSTUVWXYZ
        r=LHGKLMNOPQRSTUVWXYZ
        r=LHGKLMNOPQRSTUVWXYZ
        r=LHGKLMNOPQRSTUVWXYZ
        r=LHGKLMNOPQRSTUVWXYZ
        r=LHGKLMNOPQRSTUVWXYZ
        r=LHGKLMNOPQRSTUVWXYZ
        r=LHGKLMNOPQRSTUVWXYZ
        r=LHGKLMNOPQRSTUVWXYZ
        r=LHGKLMNOPQRSTUVWXYZ
        r=LHGKLMNOPQRSTUVWXYZ
        r=LHGKLMNOPQRSTUVWXYZ
        r=LHGKLMNOPQRSTUVWXYZ
        r=LHGKLMNOPQRSTUVWXYZ
    08-08 20:01:48.239 3795-3795/dh.fcw.cn.myapplication I/MyLog: 姓名=劉翠,年齡=0,地址=河南開封蘭考,序號=0
        姓名=劉翠,年齡=3,地址=河南開封蘭考,序號=1
        姓名=劉翠,年齡=6,地址=河南開封蘭考,序號=2
        姓名=劉翠,年齡=9,地址=河南開封蘭考,序號=3
        姓名=劉翠,年齡=12,地址=河南開封蘭考,序號=4
        姓名=劉翠,年齡=15,地址=河南開封蘭考,序號=5
        姓名=劉翠,年齡=18,地址=河南開封蘭考,序號=6
        姓名=劉翠,年齡=21,地址=河南開封蘭考,序號=7
        姓名=劉翠,年齡=24,地址=河南開封蘭考,序號=8
        姓名=劉翠,年齡=27,地址=河南開封蘭考,序號=9
        姓名=刘萍,年齡=0,地址=河南信阳新县,序號=0
        姓名=刘萍,年齡=4,地址=河南信阳新县,序號=1
        姓名=刘萍,年齡=8,地址=河南信阳新县,序號=2
        姓名=刘萍,年齡=12,地址=河南信阳新县,序號=3
        姓名=刘萍,年齡=16,地址=河南信阳新县,序號=4
        姓名=刘萍,年齡=20,地址=河南信阳新县,序號=5
        姓名=刘萍,年齡=24,地址=河南信阳新县,序號=6
        姓名=刘萍,年齡=28,地址=河南信阳新县,序號=7
        姓名=刘萍,年齡=32,地址=河南信阳新县,序號=8
    08-08 20:01:48.240 3795-3795/dh.fcw.cn.myapplication I/MyLog: 姓名=刘萍,年齡=36,地址=河南信阳新县,序號=9