用JNI实现调节win7系统音量

前言

这是我大三时写的,现在把它传到博客园给大家分享.

github地址:https://github.com/silicon621600/SiliconJNIProject/tree/master/JavaControlVolumeOfWin7

一编写包含native方法的Java类文件：

使用了异常处理机制

com.guwei,volume.VolumeControl.java文件

1. package com.guwei.volume;
2. /**
3. * 该类设计为单例模式
4. * 提供控制win7系统音量的方法
5. * @author guwei
6. *
7. */
8. public class VolumeControl {
9.      static
10.      {
11.          System.out.println(System.getProperty("java.library.path"));
12.      System.loadLibrary("VolumeControlDLL");
13.      }
14.         private static VolumeControl uniqueInstance = null;
15.  
16.         private VolumeControl() throws OperationFailedException
17.         {            
18.             init();
19.         }            
20.         /**
21.          * 单例模式
22.          * @return 唯一的VolumeControl 有可能为null
23.          */
24.         public static VolumeControl getInstance() {
25.             if (uniqueInstance == null) {
26.                 try {
27.                     uniqueInstance = new VolumeControl();
28.                 }catch (OperationFailedException e)
29.                 {
30.                     e.printStackTrace();
31.                     return null;
32.                 }
33.             }
34.             return uniqueInstance;
35.         }             
36.         /**
37.          * cpp本地一些初始化
38.          * @return
39.          */
40.         private native void init() throws OperationFailedException;
41.         /**
42.          * 设置音量大小0~100
43.          * @param num
44.          * @return 操作是否成功
45.          */
46.      public native void setMasterVolume(int num) throws OperationFailedException;
47.      /**
48.      *
49.      * @return 当前音量大小1-100
50.      */
51.         public native int getMasterVolume() throws OperationFailedException;
52.         /**
53.          * 设置是否静音 true-是 false-否
54.          * @param bMute
55.          * @return
56.          */
57.         public native void setMute(boolean bMute) throws OperationFailedException;
58.         /**
59.          * 得到当前静音状态 true-是 false-否
60.          * @return
61.          */
62.         public native boolean getMute() throws OperationFailedException;
63.         /**
64.          * cpp本地释放指针等操作
65.          * @return
66.          */
67.         private native void finished();        
68.         @Override
69.         public void finalize()
70.         {
71.             finished();
72.         }
73. }

com.guwei,volume.OperationFailedException.java文件

1. package com.guwei.volume;
2. public class OperationFailedException extends Exception
3. {
4.     public OperationFailedException()
5.     {}
6.     public OperationFailedException(String message)
7.     {
8.         super(message);
9.     }
10. }

一．编译，然后用javah命令生成相应cpp头文件

编译可用命令行javac或eclipse自动编译（javac 注意用-encoding utf8参数）

在完整.class文件位置（不是class文件的存放目录，考虑包名）使用javah命令

javah -jni com.guwei.volume.VolumeControl

也可以用-classpath指明类路径

注意要输入完整的类名，更多参数输入javah查看

命令运行完成后，会出现一个com_guwei_volume_VolumeControl.h文件

生成的头文件内容如下：

/* DO NOT EDIT THIS FILE - it is machine generated */

#include <jni.h>

/* Header for class com_guwei_volume_VolumeControl */

#ifndef _Included_com_guwei_volume_VolumeControl

#define _Included_com_guwei_volume_VolumeControl

#ifdef __cplusplus

extern "C" {

#endif

/*

* Class: com_guwei_volume_VolumeControl

* Method: init

* Signature: ()V

*/

JNIEXPORT void JNICALL Java_com_guwei_volume_VolumeControl_init

(JNIEnv *, jobject);

/*

* Class: com_guwei_volume_VolumeControl

* Method: setMasterVolume

* Signature: (I)V

*/

JNIEXPORT void JNICALL Java_com_guwei_volume_VolumeControl_setMasterVolume

(JNIEnv *, jobject, jint);

/*

* Class: com_guwei_volume_VolumeControl

* Method: getMasterVolume

* Signature: ()I

*/

JNIEXPORT jint JNICALL Java_com_guwei_volume_VolumeControl_getMasterVolume

(JNIEnv *, jobject);

/*

* Class: com_guwei_volume_VolumeControl

* Method: setMute

* Signature: (Z)V

*/

JNIEXPORT void JNICALL Java_com_guwei_volume_VolumeControl_setMute

(JNIEnv *, jobject, jboolean);

/*

* Class: com_guwei_volume_VolumeControl

* Method: getMute

* Signature: ()Z

*/

JNIEXPORT jboolean JNICALL Java_com_guwei_volume_VolumeControl_getMute

(JNIEnv *, jobject);

/*

* Class: com_guwei_volume_VolumeControl

* Method: finished

* Signature: ()V

*/

JNIEXPORT void JNICALL Java_com_guwei_volume_VolumeControl_finished

(JNIEnv *, jobject);

#ifdef __cplusplus

}

#endif

#endif

二．查询MSDN中调节wen7系统音量的方法

https://msdn.microsoft.com/zh-cn/library/windows/desktop/dd370839(v=vs.85).aspx

该网址提供一个样例VC++的win32工程显示调节系统音量,

将网页文档读懂即可编写自己的dll，其中用到了COM组件相关知识

该工程运行效果如下：

三．编写dll文件（用到了COM相关）

使用VS2010建立名为VolumeControlDLL的win32控制台工程

点下一步后 选择dll 和空项目

将jni.h和之前生成的com_guwei_volume_VolumeControl.h加入工程

jni.h在jdk目录的include目录下：

可以在VS的环境变量中加入该目录

此处我用的是直接把文件拷到当前工程，所以相应com_guwei_volume_VolumeControl.h文件中的 include <jni.h> 改为 include "jni.h"

注意头文件中的extern C 是必要的，否则会报找不到的错，这是因为CPP支持函数重载，会将函数名XX映射

另外，jdk1.7只需jni.h文件，jdk1.8还需要jni_md.h文件（include/win32目录下）根据编译信息来即可

Epvolume.cpp文件实现com_guwei_volume_VolumeControl.h的方法（根据MSDN工程中的改写）

// Epvolume.cpp -- WinMain and dialog box functions

#include
"Epvolume.h"

#include
"com_guwei_volume_VolumeControl.h"

GUID g_guidMyContext = GUID_NULL;

static
IAudioEndpointVolume *g_pEndptVol = NULL;

IMMDeviceEnumerator *pEnumerator = NULL;

IMMDevice *pDevice = NULL;

JNIEXPORT
void
JNICALL Java_com_guwei_volume_VolumeControl_init(JNIEnv *env,

jobject
obj)

{

jclass cls;

cls = env->FindClass("com/guwei/volume/OperationFailedException");

if (cls == NULL){

return;

}

HRESULT hr = S_OK;

//CAudioEndpointVolumeCallback EPVolEvents;

//得到g_guidMyContext hr只是结果

hr = CoCreateGuid(&g_guidMyContext);

if (FAILED(hr)) {

env->ThrowNew(cls, "CoCreateGuid error");

}

// Get enumerator for audio endpoint devices. pEnumerator中

hr = CoCreateInstance(__uuidof(MMDeviceEnumerator),

NULL, CLSCTX_INPROC_SERVER,

__uuidof(IMMDeviceEnumerator),

(void**)&pEnumerator);

if (FAILED(hr)) {

env->ThrowNew(cls, "CoCreateInstance error");

}

// Get default audio-rendering device. pDevice中

hr = pEnumerator->GetDefaultAudioEndpoint(eRender, eConsole, &pDevice);

if (FAILED(hr)) {

env->ThrowNew(cls, "pEnumerator->GetDefaultAudioEndpoint error");

}

hr = pDevice->Activate(__uuidof(IAudioEndpointVolume),

CLSCTX_ALL, NULL, (void**)&g_pEndptVol);

if (FAILED(hr)) {

env->ThrowNew(cls, "pDevice->Activate error");

}

}

JNIEXPORT
void
JNICALL Java_com_guwei_volume_VolumeControl_setMasterVolume(JNIEnv *env,

jobject
obj,

jint
nVolume)

{

jclass cls;

cls = env->FindClass("com/guwei/volume/OperationFailedException");

if (cls == NULL){

return;

}

float fVolume = (float)nVolume / MAX_VOL;//设置音量

HRESULT hr = g_pEndptVol->SetMasterVolumeLevelScalar(fVolume, &g_guidMyContext);

if (FAILED(hr)) {

env->ThrowNew(cls, "setMasterVolume error");

}

}

JNIEXPORT
jint
JNICALL Java_com_guwei_volume_VolumeControl_getMasterVolume(JNIEnv *env,

jobject
obj)

{

jclass cls;

cls = env->FindClass("com/guwei/volume/OperationFailedException");

if (cls == NULL){

return -1;

}

int ret;

float fVolume;

HRESULT hr = g_pEndptVol->GetMasterVolumeLevelScalar(&fVolume);//得到主音量的大小浮点数（0.0~1.0）

if (FAILED(hr)) {

env->ThrowNew(cls, "getMasterVolume error");

}

ret = (int)(MAX_VOL*fVolume + 0.5);//将音量转化为整数（0到100） MAX_VOL为100

return ret;

}

JNIEXPORT
void
JNICALL Java_com_guwei_volume_VolumeControl_setMute(JNIEnv *env,

jobject
obj,

jboolean
bMute)

{

jclass cls;

cls = env->FindClass("com/guwei/volume/OperationFailedException");

if (cls == NULL){

return;

}

HRESULT hr = g_pEndptVol->SetMute(bMute, &g_guidMyContext);//设置静音

if (FAILED(hr)) {

env->ThrowNew(cls, "setMute error");

}

}

JNIEXPORT
jboolean
JNICALL Java_com_guwei_volume_VolumeControl_getMute(JNIEnv *env,

jobject
obj)

{

jclass cls;

cls = env->FindClass("com/guwei/volume/OperationFailedException");

if (cls == NULL){

return
false;

}

BOOL bMute;//是否静音

HRESULT hr = g_pEndptVol->GetMute(&bMute);//得到静音状态

if (FAILED(hr)) {

env->ThrowNew(cls, "getMute error");

}

return bMute;

}

JNIEXPORT
void
JNICALL Java_com_guwei_volume_VolumeControl_finished(JNIEnv *env,

jobject
obj)

{

//释放指针

SAFE_RELEASE(pEnumerator)

SAFE_RELEASE(pDevice)

SAFE_RELEASE(g_pEndptVol)

}

1. 配置dll
   

   注意32位和64位系统问题，

   错误：Can‘t load IA 32-bit .dll on a AMD 64-bit platform

   由于VS生成32位的，但系统使用64位

   

   然后多了x64文件夹

   

   VC项目生成的dll在工程目录的debug(32位) 或 x64/debug(64位)目录里

   

   将该dll加入java工程的类路径（System.getProperty("java.library.path")；只要在这里面都行）即可(可以设定参数-Djava.library.path=)

   编写测试类Test.java

   import com.guwei.volume.*;

   import java.lang.Integer;

   public class Test{

   public static void main(String[] args)

   {

   VolumeControl vc = null;

   try{

   vc = VolumeControl.getInstance();

   int val = vc.getMasterVolume();

   boolean mute = vc.getMute();

   System.out.println("current volume is"+val+". Is Muted?:"+mute);

   }catch (OperationFailedException e)

   {

   System.out.println("can not read volume info: Exception:"+e);

   return ;

   }

   if (args.length>1)

   {

   String s1=args[0];

   String s2=args[1];

   if (s1.equals("setmute"))

   {

   if (s2.equals("on"))

   {

   try{

   vc.setMute(true);

   System.out.println("Operation succeed!!!");

   }catch (OperationFailedException e)

   {

   System.out.println("operation failed: Exception:"+e);

   return ;

   }

   }

   else if (s2.equals("off"))

   {

   try{

   vc.setMute(false);

   System.out.println("Operation succeed!!!");

   }catch (OperationFailedException e)

   {

   System.out.println("operation failed: Exception:"+e);

   return ;

   }

   }

   }else if (s1.equals("setvolume"))

   {

   int value = -1;

   try {

   value = Integer.parseInt(s2);

   }catch(NumberFormatException e)

   {

   System.out.println("operation failed: Exception:"+e);

   return ;

   }

   if (value>=0 && value<=100)

   {

   try{

   vc.setMasterVolume(value);

   System.out.println("Operation succeed!!!");

   }catch (OperationFailedException e)

   {

   System.out.println("operation failed: Exception:"+e);

   return ;

   }

   }

   }

   }

   }

   }