android java 调用 .so 动态库实例

MainActivity.java

package com.example.com.test.jni;

import android.view.View;
import android.view.View.OnClickListener;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity {
	
	private EditText mSetValue = null;
	private TextView mGetValue = null;
	private Button mButton = null;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		mSetValue = (EditText) findViewById(R.id.setValue);
		mGetValue = (TextView) findViewById(R.id.getValue);
		mButton = (Button) findViewById(R.id.mButton);
		mButton.setOnClickListener(new ButtonClick());
	}
	
	class ButtonClick implements OnClickListener{

		@Override
		public void onClick(View v) {
			// TODO Auto-generated method stub
			int val = Integer.parseInt(mSetValue.getText().toString());
			setValue(val);
			int temp = getValue();
			mGetValue.setText(""+temp);
		}
	}
	
	static
    {
        System.loadLibrary("testJNI");
    }
    public native static int getValue();
    public native static void setValue(int i);

}

activity_main.xml

    
    
    
    
    
    




以上是java层的代码，将Java层的代码编译成功之后 生成 MainActivity.class文件

使用 javah命令生成 JNI 的接口文件 注意：执行命令在原代码的目录下面，不要在 .class文件的目录线面。
eg:Java项目目录是 E：/TestJNI , windows 下 cmd 进入到 E：/TestJNI/src  执行 ：javah com.example.com.test.jni.MainActivity
执行前如果运行的是 Android 代码 需要在环境变量  classpath中添加 sdk的位置 

生成的
com_example_com_test_jni_MainActivity.h文件



/* DO NOT EDIT THIS FILE - it is machine generated */
#include 
/* Header for class com_example_com_test_jni_MainActivity */
#ifndef _Included_com_example_com_test_jni_MainActivity
#define _Included_com_example_com_test_jni_MainActivity
#ifdef __cplusplus
extern "C" {
#endif
#undef com_example_com_test_jni_MainActivity_BIND_ABOVE_CLIENT
#define com_example_com_test_jni_MainActivity_BIND_ABOVE_CLIENT 8L
#undef com_example_com_test_jni_MainActivity_BIND_ADJUST_WITH_ACTIVITY
#define com_example_com_test_jni_MainActivity_BIND_ADJUST_WITH_ACTIVITY 128L
#undef com_example_com_test_jni_MainActivity_BIND_ALLOW_OOM_MANAGEMENT
#define com_example_com_test_jni_MainActivity_BIND_ALLOW_OOM_MANAGEMENT 16L
#undef com_example_com_test_jni_MainActivity_BIND_AUTO_CREATE
#define com_example_com_test_jni_MainActivity_BIND_AUTO_CREATE 1L
#undef com_example_com_test_jni_MainActivity_BIND_DEBUG_UNBIND
#define com_example_com_test_jni_MainActivity_BIND_DEBUG_UNBIND 2L
#undef com_example_com_test_jni_MainActivity_BIND_IMPORTANT
#define com_example_com_test_jni_MainActivity_BIND_IMPORTANT 64L
#undef com_example_com_test_jni_MainActivity_BIND_NOT_FOREGROUND
#define com_example_com_test_jni_MainActivity_BIND_NOT_FOREGROUND 4L
#undef com_example_com_test_jni_MainActivity_BIND_WAIVE_PRIORITY
#define com_example_com_test_jni_MainActivity_BIND_WAIVE_PRIORITY 32L
#undef com_example_com_test_jni_MainActivity_CONTEXT_IGNORE_SECURITY
#define com_example_com_test_jni_MainActivity_CONTEXT_IGNORE_SECURITY 2L
#undef com_example_com_test_jni_MainActivity_CONTEXT_INCLUDE_CODE
#define com_example_com_test_jni_MainActivity_CONTEXT_INCLUDE_CODE 1L
#undef com_example_com_test_jni_MainActivity_CONTEXT_RESTRICTED
#define com_example_com_test_jni_MainActivity_CONTEXT_RESTRICTED 4L
#undef com_example_com_test_jni_MainActivity_MODE_APPEND
#define com_example_com_test_jni_MainActivity_MODE_APPEND 32768L
#undef com_example_com_test_jni_MainActivity_MODE_ENABLE_WRITE_AHEAD_LOGGING
#define com_example_com_test_jni_MainActivity_MODE_ENABLE_WRITE_AHEAD_LOGGING 8L
#undef com_example_com_test_jni_MainActivity_MODE_MULTI_PROCESS
#define com_example_com_test_jni_MainActivity_MODE_MULTI_PROCESS 4L
#undef com_example_com_test_jni_MainActivity_MODE_PRIVATE
#define com_example_com_test_jni_MainActivity_MODE_PRIVATE 0L
#undef com_example_com_test_jni_MainActivity_MODE_WORLD_READABLE
#define com_example_com_test_jni_MainActivity_MODE_WORLD_READABLE 1L
#undef com_example_com_test_jni_MainActivity_MODE_WORLD_WRITEABLE
#define com_example_com_test_jni_MainActivity_MODE_WORLD_WRITEABLE 2L
#undef com_example_com_test_jni_MainActivity_DEFAULT_KEYS_DIALER
#define com_example_com_test_jni_MainActivity_DEFAULT_KEYS_DIALER 1L
#undef com_example_com_test_jni_MainActivity_DEFAULT_KEYS_DISABLE
#define com_example_com_test_jni_MainActivity_DEFAULT_KEYS_DISABLE 0L
#undef com_example_com_test_jni_MainActivity_DEFAULT_KEYS_SEARCH_GLOBAL
#define com_example_com_test_jni_MainActivity_DEFAULT_KEYS_SEARCH_GLOBAL 4L
#undef com_example_com_test_jni_MainActivity_DEFAULT_KEYS_SEARCH_LOCAL
#define com_example_com_test_jni_MainActivity_DEFAULT_KEYS_SEARCH_LOCAL 3L
#undef com_example_com_test_jni_MainActivity_DEFAULT_KEYS_SHORTCUT
#define com_example_com_test_jni_MainActivity_DEFAULT_KEYS_SHORTCUT 2L
#undef com_example_com_test_jni_MainActivity_RESULT_CANCELED
#define com_example_com_test_jni_MainActivity_RESULT_CANCELED 0L
#undef com_example_com_test_jni_MainActivity_RESULT_FIRST_USER
#define com_example_com_test_jni_MainActivity_RESULT_FIRST_USER 1L
#undef com_example_com_test_jni_MainActivity_RESULT_OK
#define com_example_com_test_jni_MainActivity_RESULT_OK -1L
/*
 * Class:     com_example_com_test_jni_MainActivity
 * Method:    getValue
 * Signature: ()I
 */
JNIEXPORT jint JNICALL Java_com_example_com_test_jni_MainActivity_getValue
  (JNIEnv *, jobject);

/*
 * Class:     com_example_com_test_jni_MainActivity
 * Method:    setValue
 * Signature: (I)V
 */
JNIEXPORT void JNICALL Java_com_example_com_test_jni_MainActivity_setValue
  (JNIEnv *, jobject, jint);

#ifdef __cplusplus
}
#endif
#endif


 再实现对应的
com_example_com_test_jni_MainActivity.cpp文件



#include "com_example_com_test_jni_MainActivity.h"
int i = 0;

jint  Java_com_example_com_test_jni_MainActivity_getValue(JNIEnv *env, jobject jc)
{
	return i;
}

void  Java_com_example_com_test_jni_MainActivity_setValue(JNIEnv *env, jobject jc, jint j)
{
	i = j;
}


 两个文件生成之后就可以编译了

gcc -fPIC -D_REENTRANT -I /usr/lib/jvm/java-1.7.0-openjdk-amd64/include/ -I /usr/lib/jvm/java-1.7.0-openjdk-amd64/include/linux/ -c com_example_com_test_jni_MainActivity.cpp  编译目标文件 
com_example_com_test_jni_MainActivity.o



gcc -shared com_example_com_test_jni_MainActivity.o -o libtestJNI.so 生成动态库

这样生成的动态库 会有32  64 位不一致问题，具体怎么搞好没有研究


如果有Android 工程的话可以编写个 Android.mk直接编译即可
Android.mk


LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)

LOCAL_MODULE_TAGS := optional

LOCAL_MODULE := libtestJNI
LOCAL_32_BIT_ONLY := true

LOCAL_LDFLAGS += -Wl,--no-warn-shared-textrel
LOCAL_LDFLAGS += -Wl,--no-fatal-warnings

LOCAL_SRC_FILES += com_example_com_test_jni_MainActivity.cpp \
                                
include $(BUILD_SHARED_LIBRARY)


将生成的 .so文件放到app工程的 libs/armeabi 目录下面编译即可