Android JNI入门第六篇——基本数据类型使用

转载请标明出处：
http://blog.csdn.net/michael1112/article/details/56672288

江东橘子的博客

前面讲到了Java和native数据类型，这里就开始做一下使用：

       第一步：新建工程

       第二步：书写 java方法：

public class NativeMethod {

static {
System.loadLibrary("com_nedu_jni_jnidemo5-jni");
}
public native boolean getBoolean(boolean b);

public native byte getByte(byte b);

public native char getChar(char c);

public native short getShort(short s);

public native int getInt(int i);

public native long getLong(long l);

public native float getFloat(float f);

public native double getDouble(double d);
}

第三步：调用javah命令生成h文件。

第四步：补充native方法，如下

#include<stdio.h>
#include <stdlib.h>
#include "com_nedu_jni_jnidemo5_NativeMethod.h"

/*
* Class:     com_nedu_jni_jnidemo5_NativeMethod
* Method:    getBoolean
* Signature: (Z)Z
*/
JNIEXPORT jboolean JNICALL Java_com_nedu_jni_jnidemo5_NativeMethod_getBoolean
(JNIEnv *e, jobject thiz, jboolean b){

return b;
}

/*
* Class:     com_nedu_jni_jnidemo5_NativeMethod
* Method:    getByte
* Signature: (B)B
*/
JNIEXPORT jbyte JNICALL Java_com_nedu_jni_jnidemo5_NativeMethod_getByte
(JNIEnv *e, jobject thiz, jbyte by){
return by;
}

/*
* Class:     com_nedu_jni_jnidemo5_NativeMethod
* Method:    getChar
* Signature: (C)C
*/
JNIEXPORT jchar JNICALL Java_com_nedu_jni_jnidemo5_NativeMethod_getChar
(JNIEnv *e, jobject thiz, jchar c){
return c;

}

/*
* Class:     com_nedu_jni_jnidemo5_NativeMethod
* Method:    getShort
* Signature: (S)S
*/
JNIEXPORT jshort JNICALL Java_com_nedu_jni_jnidemo5_NativeMethod_getShort
(JNIEnv *e, jobject thiz, jshort s){
return s;
}

/*
* Class:     com_nedu_jni_jnidemo5_NativeMethod
* Method:    getInt
* Signature: (I)I
*/
JNIEXPORT jint JNICALL Java_com_nedu_jni_jnidemo5_NativeMethod_getInt
(JNIEnv *e, jobject thiz, jint i){
return i;
}

/*
* Class:     com_nedu_jni_jnidemo5_NativeMethod
* Method:    getLong
* Signature: (J)J
*/
JNIEXPORT jlong JNICALL Java_com_nedu_jni_jnidemo5_NativeMethod_getLong
(JNIEnv *e, jobject thiz, jlong l){

return l;
}

/*
* Class:     com_nedu_jni_jnidemo5_NativeMethod
* Method:    getFloat
* Signature: (F)F
*/
JNIEXPORT jfloat JNICALL Java_com_nedu_jni_jnidemo5_NativeMethod_getFloat
(JNIEnv *e, jobject thiz, jfloat f){
return f;
}

/*
* Class:     com_nedu_jni_jnidemo5_NativeMethod
* Method:    getDouble
* Signature: (D)D
*/
JNIEXPORT jdouble JNICALL Java_com_nedu_jni_jnidemo5_NativeMethod_getDouble
(JNIEnv *e, jobject thiz, jdouble d){

return d;
}

第五步 调用native 方法

public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

TextView text=(TextView)findViewById(R.id.text);
NativeMethod method=new NativeMethod();

text.setText("返回boolean："+method.getBoolean(true)+"\n"+
"返回byte："+method.getByte((byte) 0)+"\n"+
"返回char："+method.getChar('c')+"\n"+
"返回short："+method.getShort((short) 1)+"\n"+
"返回int："+method.getInt(1)+"\n"+
"返回long："+method.getLong(9)+"\n"+
"返回float："+method.getFloat((float) 1.0)+"\n"+
"返回double："+method.getDouble(2.0)+"\n");
}

运行结果：



总结：JNI中传过来的java基本类型可以直接使用。

/**

* @author 江东橘子

* 邮箱：whtchl@126.com

*/