JNI操作二维数组

之前的文章讲解了有关JNI使用方法，这篇文章进阶一点，介绍下JNI操作二维数组的方法。有了之前文章的操作JNI的方法，这里直接上代码了。

Java代码部分

 package com.testjni;

 public class TestJNI
 {
     private static final int ONE_DIMENSION = 3;

     private static final int TWO_DIMENSION = 2;

     public native int test2DimensionArray(int[][] aHoleList);

     static
     {
         System.load("D:\\eclipseWebWorkSpace\\testest\\src\\com\\testjni\\libTestJNI_amd64.dll");
     }

     public static void main(String[] args)
     {
         TestJNI testJNI = new TestJNI();

         //测试二维数组
         int[][] test = new int[ONE_DIMENSION][TWO_DIMENSION];
         System.out.println("\njava before--->");
         for (int i = 0; i < ONE_DIMENSION; i++)
         {
             StringBuilder sb = new StringBuilder("test[");
             for (int j = 0; j < TWO_DIMENSION; j++)
             {
                 if (j == 0)
                 {
                     sb.append(i).append("] = ").append(test[i][j]).append(" ");
                 }
                 else
                 {
                     sb.append(test[i][j]).append(" ");
                 }
             }
             System.out.println(sb.toString());
         }
         int res = testJNI.test2DimensionArray(test);

         System.out.println("\njava after--->res=" + res);
         for (int i = 0; i < ONE_DIMENSION; i++)
         {
             StringBuilder sb = new StringBuilder("test[");
             for (int j = 0; j < TWO_DIMENSION; j++)
             {
                 if (j == 0)
                 {
                     sb.append(i).append("] = ").append(test[i][j]).append(" ");
                 }
                 else
                 {
                     sb.append(test[i][j]).append(" ");
                 }
             }
             System.out.println(sb.toString());
         }
     }
 }

C头文件

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

 #ifndef _Included_com_testjni_TestJNI
 #define _Included_com_testjni_TestJNI
 #ifdef __cplusplus
 extern "C" {
 #endif
 /*
  * Class:     com_testjni_TestJNI
  * Method:    nativeBsmGetHoleList
  * Signature: ([[I)I
  */
 JNIEXPORT jint JNICALL Java_com_testjni_TestJNI_test2DimensionArray
   (JNIEnv *, jobject, jobjectArray);

 #ifdef __cplusplus
 }
 #endif
 #endif

C源码文件

 #include <stdio.h>
 #include "com_testjni_TestJNI.h"

 #define ONE_DIMENSION 3
 #define TWO_DIMENSION 2
 JNIEXPORT jint JNICALL Java_com_testjni_TestJNI_test2DimensionArray(JNIEnv *env, jobject obj, jobjectArray test)
 {
     int jniTest[ONE_DIMENSION][TWO_DIMENSION];
     for (int i = ; i < ONE_DIMENSION; i++)
     {
         for (int j = ; j < TWO_DIMENSION; j++)
         {
             jniTest[i][j] =  * (i + )+ j;
         }
     }

     printf("\njni:\n");
     jintArray testArray;
     for (int i = ; i < ONE_DIMENSION; i ++)
     {
         //从输入参数二维数组aHoleList中取出某个一维数组
         testArray = (jintArray)env->GetObjectArrayElement(test, i);
         printf("testArray[%d]=%d, %d, %d, testArray[0] addr = %d; testArray[1] addr = %d, testArray[2] addr = %d; testArray addr=%d; sizeof(jintArray)=%d\n",
             i, testArray[], testArray[], testArray[], &testArray[], &testArray[], &testArray[], testArray, sizeof(jintArray));
         //获取一维数组的指针
         jint *testP = env->GetIntArrayElements(testArray, NULL);
         printf("C before, testP[%d]=%d, %d, testP addr=%d\n", i, testP[], testP[], testP);
         //改变数组的值
         for (int j = ; j < TWO_DIMENSION; j++)
         {
              *(testP + j) = jniTest[i][j];
         }
         printf("C after, testP[%d]=%d, %d, testP addr=%d\n", i, testP[], testP[], testP);
         env->ReleaseIntArrayElements(testArray, testP, );
         printf("\n");
     }
     return ;
 }

运行结果

java before--->
test[] =
test[] =
test[] =   

java after--->res=
test[] =
test[] =
test[] =   

jni:
testArray[]=, , , testArray[] addr = ; testArray[] addr = , testArray[] addr = ; testArray addr=; sizeof(jintArray)=
C before, testP[]=, , testP addr=
C after, testP[]=, , testP addr=

testArray[]=, , , testArray[] addr = ; testArray[] addr = , testArray[] addr = ; testArray addr=; sizeof(jintArray)=
C before, testP[]=, , testP addr=
C after, testP[]=, , testP addr=

testArray[]=, , , testArray[] addr = ; testArray[] addr = , testArray[] addr = ; testArray addr=; sizeof(jintArray)=
C before, testP[]=, , testP addr=
C after, testP[]=, , testP addr=

总结：掌握C语言的核心知识点指针，各种操作水到渠成。