Jni使用过程中出现 error: request for member 'FindClass' in something not a structure or union，解决办法

谁借莪１个温暖的怀抱￠ 2022-06-18 05:55 384阅读 0赞

原文： [http://topic.csdn.net/u/20110120/10/ef601a64-27fa-4a80-96be-39dbcb644cbc.html][http_topic.csdn.net_u_20110120_10_ef601a64-27fa-4a80-96be-39dbcb644cbc.html]

## 问题： ##

在android 里使用JNI，总是报错  
packages/apps/SystemMointor/jni/proc\_reader.c:78: error: request for member 'GetStringUTFChars' in something not a structure or union  
packages/apps/SystemMointor/jni/proc\_reader.c:92: error: request for member 'FindClass' in something not a structure or union  
packages/apps/SystemMointor/jni/proc\_reader.c:94: error: request for member 'NewObjectArray' in something not a structure or union  
packages/apps/SystemMointor/jni/proc\_reader.c:96: error: request for member 'FindClass' in something not a structure or union  
packages/apps/SystemMointor/jni/proc\_reader.c:98: error: request for member 'GetFieldID' in something not a structure or union  
packages/apps/SystemMointor/jni/proc\_reader.c:99: error: request for member 'GetFieldID' in something not a structure or union  
packages/apps/SystemMointor/jni/proc\_reader.c:108: error: request for member 'SetObjectField' in something not a structure or union  
packages/apps/SystemMointor/jni/proc\_reader.c:108: error: request for member 'NewStringUTF' in something not a structure or union  
packages/apps/SystemMointor/jni/proc\_reader.c:116: error: request for member 'SetObjectField' in something not a structure or union  
packages/apps/SystemMointor/jni/proc\_reader.c:118: error: request for member 'SetObjectArray' in something not a structure or union

## 解决办法： ##

问题解决了，原来是这样的：  
如果是c程序，要用 (\*env)->  
如果是C++要用 env->  
  
ps:在linux下如果.c文件中用 “env->” 编译会找不到此结构，必须用“(\*env)->”，或者改成.cpp文件，以 c++的方式来编译。  
  
以下是两者的区别：  
  
jni.h中  
  
struct JNINativeInterface\_;  
  
struct JNIEnv\_;  
  
\#ifdef \_\_cplusplus  
typedef JNIEnv\_ JNIEnv;  
\#else  
typedef const struct JNINativeInterface\_ \*JNIEnv;  
\#endif  
  
/\*  
\* We use inlined functions for C++ so that programmers can write:  
\*  
\* env->FindClass("java/lang/String")  
\*  
\* in C++ rather than:  
\*  
\* (\*env)->FindClass(env, "java/lang/String")  
\*  
\* in C.  
\*/  
  
即C++中使用  
env->FindClass("java/lang/String")  
  
  
C中使用  
  
(\*env)->FindClass(env, "java/lang/String")

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