Android开发笔记之Jni编程第二弹
继上篇http://blog.csdn.net/u011697203/article/details/51731152博文介绍了Android studio使用jni编程的方便使用，在这篇文章中带来Android studio jni调试以及jni与java不得不说的基础故事
调试
jni调试步骤：
第一步先添加Android Native
添加完成后即可进行调试
接下来记录一下在jni学习过程中的”故事”:
其实大部分网上都有
1、jni修改java对象属性值，并回调java方法
package com.bean;
/**
* 测试的bean类
*/
public class SkillFul {
public String strSkill;
public boolean booleanSkill;
public int intSkill;
public SkillFul() {
}
}
public static native void ModifyObj(SkillFul skillFul);
JNIEXPORT void JNICALL
Java_com_test_TestJni_ModifyObj(JNIEnv *env, jclass type, jobject skillFul) {
//访问java对象的类
jclass job = (*env)->GetObjectClass(env,skillFul);
if(job == NULL){
LOGE("=========== jni %s","对象为空");
return;
}
//获得得SkillFul类的属性id
jfieldID strFieldId = (*env)->GetFieldID(env,job,"strSkill","Ljava/lang/String;");
jfieldID intFieldid = (*env)->GetFieldID(env,job,"intSkill","I");
jfieldID boolFiedid = (*env)->GetFieldID(env,job,"booleanSkill","Z");
//获得属性值
jstring strSkill = (*env)->GetObjectField(env,skillFul,strFieldId);
jint intSkill = (*env)->GetIntField(env,skillFul,intFieldid);
jboolean boolSkill = (*env)->GetBooleanField(env,skillFul,boolFiedid);
//输出jstring需要先转换为char *类型
const char * charSkill = (*env)->GetStringUTFChars(env,strSkill,0);
LOGE("==== 修改前的值:%s == %d == %d",charSkill,intSkill,boolSkill);
//修改属性值
(*env)->SetIntField(env,skillFul,intFieldid,250);
//这里个Java对象的String属性赋值，需要先将本地的string类型转换为UTF-8格式的String对象NewStringUTF
(*env)->SetObjectField(env,skillFul,strFieldId,(*env)->NewStringUTF(env,"修改后的str"));
(*env)->SetBooleanField(env,skillFul,boolFiedid,1);
// java 反射
//1 . 找到java代码的 class文件，,注意这里需要包名
jclass MainActivity = (*env)->FindClass(env,"com/ly/jnidemo/MainActivity");
if (MainActivity == 0){
LOGE("====find class MainActivity error");
return;
}
LOGE("=====find class ");
//2 寻找class里面的方法
jmethodID jmethodObj = (*env)->GetMethodID(env,MainActivity,"setSkill","(Lcom/bean/SkillFul;)V");
if (jmethodObj == 0){
LOGE("=====find method setSkill error");
return;
}
LOGE("=====find method ");
// 默认构造函数，不传参数
jmethodID construction_id = (*env)->GetMethodID(env,MainActivity,"" , "()V");
// 3 通过NewObject来创建对象
jobject mainActiviyObj = (*env)->NewObject(env,MainActivity,construction_id);
//回调Java方法
(*env)->CallVoidMethod(env,mainActiviyObj,jmethodObj,skillFul);
//用完之后释放指向UTF-8格式的char*的指针
(*env)->ReleaseStringUTFChars(env,strSkill,charSkill);
}
2、将数组传递到jni并给java多个对象赋值，并返回对象列表
public static native ArrayList getArrayObj(int[] ints);
JNIEXPORT jobject JNICALL
Java_com_test_TestJni_getArrayObj(JNIEnv *env, jclass type, jintArray ints_) {
//获取数组的长度
int length = (*env)->GetArrayLength(env,ints_);
jint *ints = (*env)->GetIntArrayElements(env, ints_, NULL);
//JNI返回arraylist类型
jclass arrayList_cla = (*env)->FindClass(env,"java/util/ArrayList");
//获取默认初始化的构造方法id
jmethodID construct = (*env)->GetMethodID(env,arrayList_cla,"" ,"()V");
jobject arrayList_obj = (*env)->NewObject(env,arrayList_cla,construct,"");
//获得arraylist的add()方法
jmethodID arrayList_add = (*env)->GetMethodID(env,arrayList_cla,"add","(Ljava/lang/Object;)Z");
//找到java代码的 class文件,注意这里需要包名
jclass SkillFul = (*env)->FindClass(env,"com/bean/SkillFul");
if (SkillFul == 0){
LOGE("====find class MainActivity error");
} else{
LOGE("=====find class ");
}
// 默认构造函数，不传参数
jmethodID construct_Skillful = (*env)->GetMethodID(env,SkillFul,"" ,"()V");
if (construct_Skillful == 0){
LOGE("====find method MainActivity error");
} else{
LOGE("=====find method ");
}
int i = 0;
//这里注意for循环会报这个错误,需要将i的初始化移出来
//Error:(74, 5) error: 'for' loop initial declarations are only allowed in C99 or C11 mode
for(; i < length; i++) {
//通过NewObject来创建对象
jobject obj_Skillful = (*env)->NewObject(env,SkillFul,construct_Skillful);
jfieldID intFieldid = (*env)->GetFieldID(env,SkillFul,"intSkill","I");
//赋值
(*env)->SetIntField(env,obj_Skillful,intFieldid,ints[i]);
(*env)->CallBooleanMethod(env,arrayList_obj,arrayList_add,obj_Skillful);
}
(*env)->ReleaseIntArrayElements(env, ints_, ints, 0);
return arrayList_obj;
}
大概就上面这些了，代码注释还是较详细
之前在网上看到一篇使用jni来实现高斯模糊的方法，在模糊之前最好先对bitmap进行缩放处理，这样能加速模糊
参考 https://github.com/qiujuer/ImageBlurring
public static native String gaussBlueBitmap(Bitmap bitmap, int r);
#include 下面的算法在网上都能找到，具体开始出自哪不知
int *blur_ARGB_8888(int *pix, int w, int h, int radius) {
int wm = w - 1;
int hm = h - 1;
int wh = w * h;
int div = radius + radius + 1;
short *r = (short *) malloc(wh * sizeof(short));
short *g = (short *) malloc(wh * sizeof(short));
short *b = (short *) malloc(wh * sizeof(short));
int rsum, gsum, bsum, x, y, i, p, yp, yi, yw;
int *vmin = (int *) malloc(MAX(w, h) * sizeof(int));
int divsum = (div + 1) >> 1;
divsum *= divsum;
short *dv = (short *) malloc(256 * divsum * sizeof(short));
for (i = 0; i < 256 * divsum; i++) {
dv[i] = (short) (i / divsum);
}
yw = yi = 0;
int(*stack)[3] = (int (*)[3]) malloc(div * 3 * sizeof(int));
int stackpointer;
int stackstart;
int *sir;
int rbs;
int r1 = radius + 1;
int routsum, goutsum, boutsum;
int rinsum, ginsum, binsum;
for (y = 0; y < h; y++) {
rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
for (i = -radius; i <= radius; i++) {
p = pix[yi + (MIN(wm, MAX(i, 0)))];
sir = stack[i + radius];
sir[0] = (p & 0xff0000) >> 16;
sir[1] = (p & 0x00ff00) >> 8;
sir[2] = (p & 0x0000ff);
rbs = r1 - ABS(i);
rsum += sir[0] * rbs;
gsum += sir[1] * rbs;
bsum += sir[2] * rbs;
if (i > 0) {
rinsum += sir[0];
ginsum += sir[1];
binsum += sir[2];
}
else {
routsum += sir[0];
goutsum += sir[1];
boutsum += sir[2];
}
}
stackpointer = radius;
for (x = 0; x < w; x++) {
r[yi] = dv[rsum];
g[yi] = dv[gsum];
b[yi] = dv[bsum];
rsum -= routsum;
gsum -= goutsum;
bsum -= boutsum;
stackstart = stackpointer - radius + div;
sir = stack[stackstart % div];
routsum -= sir[0];
goutsum -= sir[1];
boutsum -= sir[2];
if (y == 0) {
vmin[x] = MIN(x + radius + 1, wm);
}
p = pix[yw + vmin[x]];
sir[0] = (p & 0xff0000) >> 16;
sir[1] = (p & 0x00ff00) >> 8;
sir[2] = (p & 0x0000ff);
rinsum += sir[0];
ginsum += sir[1];
binsum += sir[2];
rsum += rinsum;
gsum += ginsum;
bsum += binsum;
stackpointer = (stackpointer + 1) % div;
sir = stack[(stackpointer) % div];
routsum += sir[0];
goutsum += sir[1];
boutsum += sir[2];
rinsum -= sir[0];
ginsum -= sir[1];
binsum -= sir[2];
yi++;
}
yw += w;
}
for (x = 0; x < w; x++) {
rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
yp = -radius * w;
for (i = -radius; i <= radius; i++) {
yi = MAX(0, yp) + x;
sir = stack[i + radius];
sir[0] = r[yi];
sir[1] = g[yi];
sir[2] = b[yi];
rbs = r1 - ABS(i);
rsum += r[yi] * rbs;
gsum += g[yi] * rbs;
bsum += b[yi] * rbs;
if (i > 0) {
rinsum += sir[0];
ginsum += sir[1];
binsum += sir[2];
}
else {
routsum += sir[0];
goutsum += sir[1];
boutsum += sir[2];
}
if (i < hm) {
yp += w;
}
}
yi = x;
stackpointer = radius;
for (y = 0; y < h; y++) {
// Preserve alpha channel: ( 0xff000000 & pix[yi] )
pix[yi] = (0xff000000 & pix[yi]) | (dv[rsum] << 16) | (dv[gsum] << 8) | dv[bsum];
rsum -= routsum;
gsum -= goutsum;
bsum -= boutsum;
stackstart = stackpointer - radius + div;
sir = stack[stackstart % div];
routsum -= sir[0];
goutsum -= sir[1];
boutsum -= sir[2];
if (x == 0) {
vmin[y] = MIN(y + r1, hm) * w;
}
p = x + vmin[y];
sir[0] = r[p];
sir[1] = g[p];
sir[2] = b[p];
rinsum += sir[0];
ginsum += sir[1];
binsum += sir[2];
rsum += rinsum;
gsum += ginsum;
bsum += binsum;
stackpointer = (stackpointer + 1) % div;
sir = stack[stackpointer];
routsum += sir[0];
goutsum += sir[1];
boutsum += sir[2];
rinsum -= sir[0];
ginsum -= sir[1];
binsum -= sir[2];
yi += w;
}
}
free(r);
free(g);
free(b);
free(vmin);
free(dv);
free(stack);
return (pix);
}
short *blur_RGB_565(short *pix, int w, int h, int radius) {
int wm = w - 1;
int hm = h - 1;
int wh = w * h;
int div = radius + radius + 1;
short *r = (short *) malloc(wh * sizeof(short));
short *g = (short *) malloc(wh * sizeof(short));
short *b = (short *) malloc(wh * sizeof(short));
int rsum, gsum, bsum, x, y, p, i, yp, yi, yw;
int *vmin = (int *) malloc(MAX(w, h) * sizeof(int));
int divsum = (div + 1) >> 1;
divsum *= divsum;
short *dv = (short *) malloc(256 * divsum * sizeof(short));
for (i = 0; i < 256 * divsum; i++) {
dv[i] = (short) (i / divsum);
}
yw = yi = 0;
int(*stack)[3] = (int (*)[3]) malloc(div * 3 * sizeof(int));
int stackpointer;
int stackstart;
int *sir;
int rbs;
int r1 = radius + 1;
int routsum, goutsum, boutsum;
int rinsum, ginsum, binsum;
for (y = 0; y < h; y++) {
rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
for (i = -radius; i <= radius; i++) {
p = pix[yi + (MIN(wm, MAX(i, 0)))];
sir = stack[i + radius];
sir[0] = (((p) & 0xF800) >> 11) << 3;
sir[1] = (((p) & 0x7E0) >> 5) << 2;
sir[2] = ((p) & 0x1F) << 3;
rbs = r1 - ABS(i);
rsum += sir[0] * rbs;
gsum += sir[1] * rbs;
bsum += sir[2] * rbs;
if (i > 0) {
rinsum += sir[0];
ginsum += sir[1];
binsum += sir[2];
}
else {
routsum += sir[0];
goutsum += sir[1];
boutsum += sir[2];
}
}
stackpointer = radius;
for (x = 0; x < w; x++) {
r[yi] = dv[rsum];
g[yi] = dv[gsum];
b[yi] = dv[bsum];
rsum -= routsum;
gsum -= goutsum;
bsum -= boutsum;
stackstart = stackpointer - radius + div;
sir = stack[stackstart % div];
routsum -= sir[0];
goutsum -= sir[1];
boutsum -= sir[2];
if (y == 0) {
vmin[x] = MIN(x + radius + 1, wm);
}
p = pix[yw + vmin[x]];
sir[0] = (((p) & 0xF800) >> 11) << 3;
sir[1] = (((p) & 0x7E0) >> 5) << 2;
sir[2] = ((p) & 0x1F) << 3;
rinsum += sir[0];
ginsum += sir[1];
binsum += sir[2];
rsum += rinsum;
gsum += ginsum;
bsum += binsum;
stackpointer = (stackpointer + 1) % div;
sir = stack[(stackpointer) % div];
routsum += sir[0];
goutsum += sir[1];
boutsum += sir[2];
rinsum -= sir[0];
ginsum -= sir[1];
binsum -= sir[2];
yi++;
}
yw += w;
}
for (x = 0; x < w; x++) {
rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
yp = -radius * w;
for (i = -radius; i <= radius; i++) {
yi = MAX(0, yp) + x;
sir = stack[i + radius];
sir[0] = r[yi];
sir[1] = g[yi];
sir[2] = b[yi];
rbs = r1 - ABS(i);
rsum += r[yi] * rbs;
gsum += g[yi] * rbs;
bsum += b[yi] * rbs;
if (i > 0) {
rinsum += sir[0];
ginsum += sir[1];
binsum += sir[2];
}
else {
routsum += sir[0];
goutsum += sir[1];
boutsum += sir[2];
}
if (i < hm) {
yp += w;
}
}
yi = x;
stackpointer = radius;
for (y = 0; y < h; y++) {
// Not have alpha channel
pix[yi] = ((((dv[rsum]) >> 3) << 11) | (((dv[gsum]) >> 2) << 5) | ((dv[bsum]) >> 3));
rsum -= routsum;
gsum -= goutsum;
bsum -= boutsum;
stackstart = stackpointer - radius + div;
sir = stack[stackstart % div];
routsum -= sir[0];
goutsum -= sir[1];
boutsum -= sir[2];
if (x == 0) {
vmin[y] = MIN(y + r1, hm) * w;
}
p = x + vmin[y];
sir[0] = r[p];
sir[1] = g[p];
sir[2] = b[p];
rinsum += sir[0];
ginsum += sir[1];
binsum += sir[2];
rsum += rinsum;
gsum += ginsum;
bsum += binsum;
stackpointer = (stackpointer + 1) % div;
sir = stack[stackpointer];
routsum += sir[0];
goutsum += sir[1];
boutsum += sir[2];
rinsum -= sir[0];
ginsum -= sir[1];
binsum -= sir[2];
yi += w;
}
}
free(r);
free(g);
free(b);
free(vmin);
free(dv);
free(stack);
return (pix);
}