JNI findClass的返回NULL

我得到的C++結構在頭文件，JNI findClass的返回NULL

struct StatusLine 
{ 
    static jclass Class; // Lorg/apache/http/StatusLine; 
    static jmethodID GetStatusCode; //()I 
}; 

struct ByteArrayOutputStream 
{ 
    static jclass Class; // Ljava/io/ByteArrayOutputStream; 
    static jmethodID Constructor; //()V 
    static jmethodID Close; //()V 
    static jmethodID ToByteArray; //()[B 
}; 

struct HttpEntity 
{ 
    static jclass Class; // Lorg/apache/http/HttpEntity; 
    static jmethodID WriteTo; // (Ljava/io/OutputStream;)V 
    static jmethodID GetContent; //()Ljava/io/InputStream; 
};

和CPP文件是

#define JAVA_STATUS_LINE_CLASS    "org/apache/http/StatusLine" 
#define JAVA_HTTP_ENTITY_CLASS    "org/apache/http/HttpEntity" 
#define JAVA_BYTE_ARRAY_OUTPUT_STREAM_CLASS "java/io/ByteArrayOutputStream" 

jclass StatusLine::Class = 0; 
jmethodID StatusLine::GetStatusCode = 0; 

jclass ByteArrayOutputStream::Class = 0; 
jmethodID ByteArrayOutputStream::Constructor = 0; 
jmethodID ByteArrayOutputStream::Close = 0; 
jmethodID ByteArrayOutputStream::ToByteArray = 0; 

jclass HttpEntity::Class = 0; 
jmethodID HttpEntity::WriteTo = 0; 
jmethodID HttpEntity::GetContent = 0; 

void initializeJniPointers() 
{ 
     StatusLine::Class = GetJniEnv()->FindClass(JAVA_STATUS_LINE_CLASS); 
     StatusLine::GetStatusCode = GetJniEnv()->GetMethodID(StatusLine::Class, "getStatusCode", "()I"); 


     ByteArrayOutputStream::Class = GetJniEnv()->FindClass(JAVA_BYTE_ARRAY_OUTPUT_STREAM_CLASS); 
     ByteArrayOutputStream::Constructor = GetJniEnv()->GetMethodID(ByteArrayOutputStream::Class, "<init>", "()V"); 
     ByteArrayOutputStream::Close = GetJniEnv()->GetMethodID(ByteArrayOutputStream::Class, "close", "()V"); 
     ByteArrayOutputStream::ToByteArray = GetJniEnv()->GetMethodID(ByteArrayOutputStream::Class, "toByteArray", "()[B"); 

     HttpEntity::Class = GetJniEnv()->FindClass(JAVA_HTTP_ENTITY_CLASS); 
     HttpEntity::WriteTo = GetJniEnv()->GetMethodID(HttpEntity::Class, "writeTo", "(Ljava/io/OutputStream;)V"); 
     HttpEntity::GetContent = GetJniEnv()->GetMethodID(HttpEntity::Class, "getContent", "()Ljava/io/InputStream;"); 
}

功能initializeJniPointers（）壓碎上線狀態行:: GetStatusCode = GetJniEnv（） - >的GetMethodID（）;因爲StatusLine :: Class是NULL。但是！我注意到：如果我寫這個項目狀態行升一些Java文件=新StatuLine（）{ ... }

功能上ByteArrayOutputStream擊碎::構造，因爲ByteArrayOutputStream ::類爲null ，如果我在java中創建一個ByteArrayOutputStream對象，函數將進一步到下一個對象，等等......我注意到：如果我只聲明ByteArrayOutputStream的變量，findClass將返回NULL。

有人能解釋我該怎麼做嗎？順便說一下，我使用Android 2.3.5設備三星GT-S5363，我嘗試了其他android（老人）和設備的頂點，它工作正常。

來源

2014-09-29 theroom101