Android JNI学习(二)——实战JNI之“hello world”

package gebilaolitou.ndkdemo;

public class NDKTools {

    public static native String getStringFromNDK();

}

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="gebilaolitou.ndkdemo.MainActivity">

    <TextView
        android:id="@+id/tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>

package gebilaolitou.ndkdemo;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        String text = NDKTools.getStringFromNDK();
        Log.i("gebilaolitou","text="+text);
        ((TextView)findViewById(R.id.tv)).setText(text);
    }
}

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class gebilaolitou_ndkdemo_NDKTools */

#ifndef _Included_gebilaolitou_ndkdemo_NDKTools
#define _Included_gebilaolitou_ndkdemo_NDKTools
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     gebilaolitou_ndkdemo_NDKTools
 * Method:    getStringFromNDK
 * Signature: ()Ljava/lang/String;
 */
JNIEXPORT jstring JNICALL Java_gebilaolitou_ndkdemo_NDKTools_getStringFromNDK
  (JNIEnv *, jclass);

#ifdef __cplusplus
}
#endif
#endif

#include "gebilaolitou_ndkdemo_NDKTools.h"

JNIEXPORT jstring JNICALL Java_gebilaolitou_ndkdemo_NDKTools_getStringFromNDK
  (JNIEnv *env, jobject obj){
     return (*env)->NewStringUTF(env,"Hellow World，这是隔壁老李头的NDK的第一行代码");
  }

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE    := ndkdemotest-jni

LOCAL_SRC_FILES := ndkdemotest.c

include $(BUILD_SHARED_LIBRARY)

Error:Execution failed for task ':app:compileDebugNdk'.
> Error: Flag android.useDeprecatedNdk is no longer supported and will be removed in the next version of Android Studio.  Please switch to a supported build system.
  Consider using CMake or ndk-build integration. For more information, go to:
   https://d.android.com/r/studio-ui/add-native-code.html#ndkCompile
   To get started, you can use the sample ndk-build script the Android
   plugin generated for you at:
   /Users/gebilaolitou/AndroidStudioProjects/JNIDemo/app/build/intermediates/ndk/debug/Android.mk
  Alternatively, you can use the experimental plugin:
   https://developer.android.com/r/tools/experimental-plugin.html
  To continue using the deprecated NDK compile for another 60 days, set 
  android.deprecatedNdkCompileLease=1523001628930 in gradle.properties

ndk.dir=/Users/debilaolitouLibrary/Android/sdk/ndk-bundle
sdk.dir=/Users/debilaolitouLibrary/Library/Android/sdk

apply plugin: 'com.android.application'

android {
    compileSdkVersion 26
    defaultConfig {
        applicationId "gebilaolitou.ndkdemo"
        minSdkVersion 19
        targetSdkVersion 26
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

        ndk{

            moduleName "ndkdemotest-jni"
            abiFilters "armeabi", "armeabi-v7a", "x86"

        }
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
        externalNativeBuild {
            ndkBuild {
                path 'src/main/jni/Android.mk'
            }
        }
        sourceSets.main {
            jni.srcDirs = []
            jniLibs.srcDirs = ['src/main/jniLibs']
        }
    }
}

public class NDKTools {

    static {
        System.loadLibrary("ndkdemotest-jni");
    }

    public static native String getStringFromNDK();
}

Error:Execution failed for task ':app:compileDebugNdk'.
> Error: Your project contains C++ files but it is not using a supported native build system.
  Consider using CMake or ndk-build integration. For more information, go to:
   https://d.android.com/r/studio-ui/add-native-code.html
  Alternatively, you can use the experimental plugin:
   https://developer.android.com/r/tools/experimental-plugin.html

Android.useDeprecatedNdk=true 

apply plugin: 'com.android.application'

android {
    compileSdkVersion 26
    defaultConfig {
        applicationId "gebilaolitou.cmakendkdemo"
        minSdkVersion 23
        targetSdkVersion 26
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        externalNativeBuild {
            cmake {
                cppFlags ""
            }
        }
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
    externalNativeBuild {
        cmake {
            path "CMakeLists.txt"
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:26.1.0'
    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.1'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
}

arguments : 
-H/Users/gebilaolitou/Desktop/codeLib/CMakeNDKDemo/app
-B/Users/gebilaolitou/Desktop/codeLib/CMakeNDKDemo/app/.externalNativeBuild/cmake/debug/x86
-DANDROID_ABI=x86
-DANDROID_PLATFORM=android-23
-DCMAKE_LIBRARY_OUTPUT_DIRECTORY=/Users/gebilaolitou/Desktop/codeLib/CMakeNDKDemo/app/build/intermediates/cmake/debug/obj/x86
-DCMAKE_BUILD_TYPE=Debug
-DANDROID_NDK=/Users/gebilaolitou/Library/Android/sdk/ndk-bundle
-DCMAKE_CXX_FLAGS=
-DCMAKE_TOOLCHAIN_FILE=/Users/gebilaolitou/Library/Android/sdk/ndk-bundle/build/cmake/android.toolchain.cmake
-DCMAKE_MAKE_PROGRAM=/Users/gebilaolitou/Library/Android/sdk/cmake/3.6.4111459/bin/ninja
-GAndroid Gradle - Ninja
jvmArgs : 

# For more information about using CMake with Android Studio, read the
# documentation: https://d.android.com/studio/projects/add-native-code.html

# Sets the minimum version of CMake required to build the native library.

cmake_minimum_required(VERSION 3.4.1)

# Creates and names a library, sets it as either STATIC
# or SHARED, and provides the relative paths to its source code.
# You can define multiple libraries, and CMake builds them for you.
# Gradle automatically packages shared libraries with your APK.

add_library( # Sets the name of the library.
             native-lib

             # Sets the library as a shared library.
             SHARED

             # Provides a relative path to your source file(s).
             src/main/cpp/native-lib.cpp )

# Searches for a specified prebuilt library and stores the path as a
# variable. Because CMake includes system libraries in the search path by
# default, you only need to specify the name of the public NDK library
# you want to add. CMake verifies that the library exists before
# completing its build.

find_library( # Sets the name of the path variable.
              log-lib

              # Specifies the name of the NDK library that
              # you want CMake to locate.
              log )

# Specifies libraries CMake should link to your target library. You
# can link multiple libraries, such as libraries you define in this
# build script, prebuilt third-party libraries, or system libraries.

target_link_libraries( # Specifies the target library.
                       native-lib

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

cmake_minimum_required(VERSION 3.4.1)

add_library( # Sets the name of the library.
             native-lib

             # Sets the library as a shared library.
             SHARED

             # Provides a relative path to your source file(s).
             src/main/cpp/native-lib.cpp )


find_library( # Sets the name of the path variable.
              log-lib

              # Specifies the name of the NDK library that
              # you want CMake to locate.
              log )

target_link_libraries( # Specifies the target library.
                       native-lib

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

cmake_minimum_required(VERSION 3.4.1)

add_library( # Sets the name of the library. 
             native-lib
             # Sets the library as a shared library.
             SHARED
             # Provides a relative path to your source file(s). 
             src/main/cpp/native-lib.cpp )

find_library( # Defines the name of the path variable that stores the
              # location of the NDK library.
              log-lib

              # Specifies the name of the NDK library that
              # CMake needs to locate.
              log )
              

target_link_libraries( # Specifies the target library.
                       native-lib

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

apply plugin: 'com.android.application'

android {
    compileSdkVersion 26
    defaultConfig {
        applicationId "gebilaolitou.ndkdemo"
        minSdkVersion 19
        targetSdkVersion 26
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }

    }

    externalNativeBuild {
        cmake {
            path 'CMakeLists.txt'
        }
    }
}

#include <jni.h>
#include <string>

extern "C"
JNIEXPORT jstring

JNICALL
Java_gebilaolitou_ndkdemo_NDKTools_getStringFromNDK(
        JNIEnv *env, jobject /* this */) {
    std::string hello = "(*^__^*) 嘻嘻……~Hello from C++ 隔壁老李头";
    return env->NewStringUTF(hello.c_str());
}

package gebilaolitou.ndkdemo;


public class NDKTools {

    static {
        System.loadLibrary("native-lib");
    }

    public static native String getStringFromNDK();
}