最終更新:2018-12-13 (木) 14:46:36 (1967d)  

Android Studio/プロジェクト/NDK

テンプレートの差分

↑

Android Studio/プロジェクト/app/build.gradle 

  • android {
    compileSdkVersion 25
    buildToolsVersion "25.0.2"
    defaultConfig {
        applicationId "com.example.test.myapplication"
        minSdkVersion 15
        targetSdkVersion 25
        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"
+        }
+    }
}
  • externalNativeBuild
↑

Android Studio/プロジェクト/app/CMakeLists.txt 

  • # 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} )
  • add_library
  • find_library
  • target_link_libraries
↑

Android Studio/プロジェクト/app/src/main/cpp/native-lib.cpp 

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

extern "C"
JNIEXPORT jstring JNICALL
Java_com_example_test_myapplication_MainActivity_stringFromJNI(
        JNIEnv *env,
        jobject /* this */) {
    std::string hello = "Hello from C++";
    return env->NewStringUTF(hello.c_str());
}
  • JNI
  • JNICALL?
  • JNIEXPORT
↑

Android Studio/プロジェクト/app/src/main/java/com/example/test/myapplication/MainActivity.java 

  • package com.example.test.myapplication;

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

public class MainActivity extends AppCompatActivity {

+    // Used to load the 'native-lib' library on application startup.
+    static {
+        System.loadLibrary("native-lib");
+    }

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

+        // Example of a call to a native method
+        TextView tv = (TextView) findViewById(R.id.sample_text);
+        tv.setText(stringFromJNI());
    }

+    /**
+     * A native method that is implemented by the 'native-lib' native library,
+     * which is packaged with this application.
+     */
+    public native String stringFromJNI();
}
  • native
  • System.loadLibrary



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