如何导入.dll文件到Android的Java项目（使用Eclipse工作）文件、项目、工作、dll

2023-09-05 04:13:21 作者：丿噉檤灬丿夨呿灬

Java本地接口（JNI）

Java Native Interface (JNI)

Java本地接口（JNI）是一个该野趣接口在Java通过使用Java Native Interface（JNI）你可以与其他应用程序操作和库

Java Native Interface (JNI) is one of the intersting interface by java By using Java Native Interface (JNI) you can operate with other applications and libraries.

JNI是JDK的一部分的本地编程接口的Java。使用JNI，你可以与其他应用程序，并用其他语言如C，C ++库操作。但是，当我应该使用JNI的基本问题是？

JNI is the native programming interface for java that is part of JDK. Using JNI you can operate with other applications and libraries written in other language such as C,C++. But the basic question arises when should I use the JNI ?

您需要一些平台的信息和标准的Java类库可能不支持应用程序所需的平台相关的功能。您有一些库应用程序用其它语言，你想用它在你的Java应用程序。您希望Java应该有一些低层次的编程语言交互。 You want some platform specific information and the standard Java class library may not support the platform-dependent features needed by your application. You have some library application written in other language and you want to use it in your java application. You want Java should interact with some low level programming language.

下面给出简单的例子;请参阅方法有'本土'关键字：

Below is given Simple Example; See that methods have 'native' KeyWord:

public native void displayHelloWorld();
public native void displayOther();
private native String getLine(String prompt);

我们将使用的DLL是firstJNI.DLL这个DLL可以通过VC ++或Borland的产生。我们将在后面讨论。

The DLL we are going to use is firstJNI.DLL This DLL can be generated by VC++ or borland. Which we will discuss later.

//firstJNI.java

class firstJNI
{
    public native void displayHelloWorld();
    public native void displayOther();
    private native String getLine(String prompt);

    static {
     System.loadLibrary("firstJNI");//This is firstJNI.DLL
     /*if generated by borland
     System.loadLibrary("firstjni");//This is firstjni.dll
     */
    }

     public static void main(String[] args) 
     {
        firstJNI JN=new firstJNI();
        JN.displayHelloWorld();
        JN.displayOther();
        
        String input = JN.getLine("Enter Some Thing "); 
        System.out.println("You Entered " + input); 
     }
}

使用编译上面的code （这是什么意思？）

prompt>javac firstJNI.java

然后使用创建的头文件（这是什么意思？）

prompt>javah javah -jni HelloWorld

这将创建firstJNI.h文件。在头文件，你会看到

This will create firstJNI.h file. In the header File you will see

-------------------------------------
JNIEXPORT void JNICALL Java_firstJNI_displayHelloWorld
(JNIEnv *, jobject);

/*
 * Class:     firstJNI
 * Method:    displayOther
 * Signature: ()V
 */
JNIEXPORT void JNICALL Java_firstJNI_displayOther
  (JNIEnv *, jobject);

/*
 * Class:     firstJNI
 * Method:    getLine
 * Signature: (Ljava/lang/String;)Ljava/lang/String;
 */
JNIEXPORT jstring JNICALL Java_firstJNI_getLine
  (JNIEnv *, jobject, jstring);
----------------------------------------------

不要编辑头文件

Don't edit header File

现在让我们看看如何使用VC ++生成的DLL，请点击：文件 - >新建 - > Win32Dynamic链接库给出名称和选择一个简单的DLL项目你将会拥有 firstJNI.CPP文件下面给出的firstJNI.cpp文件

Now let see how to generate DLL using VC++, Click: File->New->Win32Dynamic-Link Library Give name and Select A simple DLL project You will have firstJNI.CPP file Below is given the firstJNI.cpp file

// MYVCDLL.cpp : Defines the entry point for the DLL application.
//

#include "stdafx.h"
#include "D:\Kanad\Study\codeToad Articles\firstJNI.h"
#include "jni.h" //can copy or give full path
#include <math.h>

BOOL APIENTRY DllMain( HANDLE hModule, 
                       DWORD  ul_reason_for_call, 
                       LPVOID lpReserved
                     )
{
    return TRUE;
}

extern "C" __declspec(dllexport) int getMemorySize();
//And your function definition should look like this: 
extern "C" __declspec(dllexport) int getMemorySize()
{     //do something 

MEMORYSTATUS memoryStatus;  
int MB=1024*1024 ;
double memSize;  
memoryStatus.dwLength=sizeof(MEMORYSTATUS);  

GlobalMemoryStatus(&memoryStatus);  

__int64 size= memoryStatus.dwTotalPhys;  

memSize=(double)size/MB;  

printf("\nTotal Memory %.0lf MB",ceil(memSize));

 return 0;
}

JNIEXPORT void JNICALL 
Java_firstJNI_displayHelloWorld(JNIEnv *env, jobject obj) 
{
    printf("Hello world! This is using VC++ DLL\n");

}

JNIEXPORT void JNICALL 
Java_firstJNI_displayOther(JNIEnv *env, jobject obj) 
{
    
    printf("Hello world! This is using VC++ DLL Other Function \n");
    getMemorySize();
    
}

JNIEXPORT jstring JNICALL
Java_firstJNI_getLine(JNIEnv *env, jobject obj, jstring enter)
{

    char buf[128];
    const char *str = env->GetStringUTFChars(enter, 0);
    printf("\n%s", str);
    env->ReleaseStringUTFChars(enter, str);
    scanf("%s", buf);
    return env->NewStringUTF(buf);

}

现在我对我怎么可以用写在C ++ / C .dll文件在我的Java应用程序的问题。我开发的应用程序使用Eclipse Android和我有一些dll文件，我还没有自己的源代码...我如何使用他们在我的项目???

如何导入.dll文件到Android的Java项目（使用Eclipse工作）文件、项目、工作、dll

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