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

 1 package com.testjni;
 2 
 3 public class TestJNI
 4 {
 5     private static final int ONE_DIMENSION = 3;
 6 
 7     private static final int TWO_DIMENSION = 2;
 8 
 9     public native int test2DimensionArray(int[][] aHoleList);
10 
11     static
12     {
13         System.load("D:\\eclipseWebWorkSpace\\testest\\src\\com\\testjni\\libTestJNI_amd64.dll");
14     }
15 
16     public static void main(String[] args)
17     {
18         TestJNI testJNI = new TestJNI();
19 
20         //测试二维数组
21         int[][] test = new int[ONE_DIMENSION][TWO_DIMENSION];
22         System.out.println("\njava before--->");
23         for (int i = 0; i < ONE_DIMENSION; i++)
24         {
25             StringBuilder sb = new StringBuilder("test[");
26             for (int j = 0; j < TWO_DIMENSION; j++)
27             {
28                 if (j == 0)
29                 {
30                     sb.append(i).append("] = ").append(test[i][j]).append(" ");
31                 }
32                 else
33                 {
34                     sb.append(test[i][j]).append(" ");
35                 }
36             }
37             System.out.println(sb.toString());
38         }
39         int res = testJNI.test2DimensionArray(test);
40 
41         System.out.println("\njava after--->res=" + res);
42         for (int i = 0; i < ONE_DIMENSION; i++)
43         {
44             StringBuilder sb = new StringBuilder("test[");
45             for (int j = 0; j < TWO_DIMENSION; j++)
46             {
47                 if (j == 0)
48                 {
49                     sb.append(i).append("] = ").append(test[i][j]).append(" ");
50                 }
51                 else
52                 {
53                     sb.append(test[i][j]).append(" ");
54                 }
55             }
56             System.out.println(sb.toString());
57         }
58     }
59 }

 


C头文件
 1 /* DO NOT EDIT THIS FILE - it is machine generated */
 2 #include "jni.h"
 3 /* Header for class com_testjni_TestJNI */
 4 
 5 #ifndef _Included_com_testjni_TestJNI
 6 #define _Included_com_testjni_TestJNI
 7 #ifdef __cplusplus
 8 extern "C" {
 9 #endif
10 /*
11  * Class:     com_testjni_TestJNI
12  * Method:    nativeBsmGetHoleList
13  * Signature: ([[I)I
14  */
15 JNIEXPORT jint JNICALL Java_com_testjni_TestJNI_test2DimensionArray
16   (JNIEnv *, jobject, jobjectArray);
17 
18 #ifdef __cplusplus
19 }
20 #endif
21 #endif

C源码文件
 1 #include <stdio.h>
 2 #include "com_testjni_TestJNI.h"
 3 
 4 #define ONE_DIMENSION 3
 5 #define TWO_DIMENSION 2
 6 JNIEXPORT jint JNICALL Java_com_testjni_TestJNI_test2DimensionArray(JNIEnv *env, jobject obj, jobjectArray test)
 7 {
 8     int jniTest[ONE_DIMENSION][TWO_DIMENSION];
 9     for (int i = 0; i < ONE_DIMENSION; i++)
10     {
11         for (int j = 0; j < TWO_DIMENSION; j++)
12         {
13             jniTest[i][j] = 10 * (i + 1)+ j;
14         }
15     }
16 
17     printf("\njni:\n");
18     jintArray testArray;
19     for (int i = 0; i < ONE_DIMENSION; i ++)
20     {
21         //从输入参数二维数组aHoleList中取出某个一维数组
22         testArray = (jintArray)env->GetObjectArrayElement(test, i);
23         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", 
24             i, testArray[0], testArray[1], testArray[2], &testArray[0], &testArray[1], &testArray[2], testArray, sizeof(jintArray));
25         //获取一维数组的指针
26         jint *testP = env->GetIntArrayElements(testArray, NULL);
27         printf("C before, testP[%d]=%d, %d, testP addr=%d\n", i, testP[0], testP[1], testP);
28         //改变数组的值
29         for (int j = 0; j < TWO_DIMENSION; j++)
30         {
31              *(testP + j) = jniTest[i][j];
32         }
33         printf("C after, testP[%d]=%d, %d, testP addr=%d\n", i, testP[0], testP[1], testP);
34         env->ReleaseIntArrayElements(testArray, testP, 0);
35         printf("\n");
36     }
37     return 666;
38 }

运行结果
java before--->
test[0] = 0 0 
test[1] = 0 0 
test[2] = 0 0 

java after--->res=666
test[0] = 10 11 
test[1] = 20 21 
test[2] = 30 31 

jni:
testArray[0]=200, 149, 5485270, testArray[0] addr = 475516656; testArray[1] addr = 475516657, testArray[2] addr = 475516658; testArray addr=475516656; sizeof(jintArray)=8
C before, testP[0]=0, 0, testP addr=38368912
C after, testP[0]=10, 11, testP addr=38368912

testArray[1]=224, 149, 38368982, testArray[0] addr = 475516664; testArray[1] addr = 475516665, testArray[2] addr = 475516666; testArray addr=475516664; sizeof(jintArray)=8
C before, testP[1]=0, 0, testP addr=38368912
C after, testP[1]=20, 21, testP addr=38368912

testArray[2]=248, 149, 38368982, testArray[0] addr = 475516672; testArray[1] addr = 475516673, testArray[2] addr = 475516674; testArray addr=475516672; sizeof(jintArray)=8
C before, testP[2]=0, 0, testP addr=38368912
C after, testP[2]=30, 31, testP addr=38368912

 

总结：掌握C语言的核心知识点指针，各种操作水到渠成。