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如何读取注册表键值

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如何读取注册表键值

发表于：2007-09-02 09:20:24 楼主

dim name as string, ret as long, hkey as long
ret = regopenkey（hkey_current_user, "software\microsoft\multimedia\sound mapper ", hkey)
if ret = 0 then
ret = regqueryvalueex（hkey, "playback ", 0, reg_sz, byval name, 255)
msgbox name
end if

请问以上代码有错吗?怎么读出来是空值?

发表于：2007-09-02 09:44:131楼得分:0

' 这个模块用于读和写注册表关键字。
' 不同于vb 的内部注册表访问方法，它可以
' 通过字符串的值来读和写任何注册表关键字。

'---------------------------------------------------------------
'-注册表 api 声明...
'---------------------------------------------------------------
private declare function regclosekey lib "advapi32 " （byval hkey as long) as long
private declare function regcreatekeyex lib "advapi32 " alias "regcreatekeyexa " （byval hkey as long, byval lpsubkey as string, byval reserved as long, byval lpclass as string, byval dwoptions as long, byval samdesired as long, byref lpsecurityattributes as security_attributes, byref phkresult as long, byref lpdwdisposition as long) as long
private declare function regopenkeyex lib "advapi32 " alias "regopenkeyexa " （byval hkey as long, byval lpsubkey as string, byval uloptions as long, byval samdesired as long, byref phkresult as long) as long
private declare function regqueryvalueex lib "advapi32 " alias "regqueryvalueexa " （byval hkey as long, byval lpvaluename as string, byval lpreserved as long, byref lptype as long, byval lpdata as string, byref lpcbdata as long) as long
private declare function regsetvalueex lib "advapi32 " alias "regsetvalueexa " （byval hkey as long, byval lpvaluename as string, byval reserved as long, byval dwtype as long, byval lpdata as string, byval cbdata as long) as long

'---------------------------------------------------------------
'- 注册表 api 常数...
'---------------------------------------------------------------
' reg data types...
const reg_sz = 1 ' unicode空终结字符串
const reg_expand_sz = 2 ' unicode空终结字符串
const reg_dword = 4 ' 32-bit 数字

' 注册表创建类型值...
const reg_option_non_volatile = 0 ' 当系统重新启动时，关键字被保留

' 注册表关键字安全选项...
const read_control = &h20000
const key_query_value = &h1
const key_set_value = &h2
const key_create_sub_key = &h4
const key_enumerate_sub_keys = &h8
const key_notify = &h10
const key_create_link = &h20
const key_read = key_query_value + key_enumerate_sub_keys + key_notify + read_control
const key_write = key_set_value + key_create_sub_key + read_control
const key_ＥＸＥＣute = key_read
const key_all_access = key_query_value + key_set_value + _
key_create_sub_key + key_enumerate_sub_keys + _
key_notify + key_create_link + read_control

' 注册表关键字根类型...
const hkey_classes_root = &h80000000
const hkey_current_user = &h80000001
const hkey_local_machine = &h80000002
const hkey_users = &h80000003
const hkey_performance_data = &h80000004

' 返回值...
const error_none = 0
const error_badkey = 2
const error_access_denied = 8
const error_success = 0

'---------------------------------------------------------------
'- 注册表安全属性类型...
'---------------------------------------------------------------
private type security_attributes
nlength as long
lpsecuritydescriptor as long
binherithandle as boolean
end type

发表于：2007-09-02 09:44:172楼得分:0

'-------------------------------------------------------------------------------------------------
'sample usage - debug.print upodatekey（hkey_classes_root, "keyname ", "newvalue ")
'-------------------------------------------------------------------------------------------------
public function updatekey（keyroot as long, keyname as string, subkeyname as string, subkeyvalue as string) as boolean
dim rc as long ' 返回代码
dim hkey as long ' 处理一个注册表关键字
dim hdepth as long '
dim lpattr as security_attributes ' 注册表安全类型

lpattr.nlength = 50 ' 设置安全属性为缺省值...
lpattr.lpsecuritydescriptor = 0 ' ...
lpattr.binherithandle = true ' ...

'------------------------------------------------------------
'- 创建/打开注册表关键字...
'------------------------------------------------------------
rc = regcreatekeyex（keyroot, keyname, _
0, reg_sz, _
reg_option_non_volatile, key_all_access, lpattr, _
hkey, hdepth) ' 创建/打开//keyroot//keyname

if （rc <> error_success) then goto createkeyerror ' 错误处理...

'------------------------------------------------------------
'- 创建/修改关键字值...
'------------------------------------------------------------
if （subkeyvalue = " ") then subkeyvalue = " " ' 要让regsetvalueex（) 工作需要输入一个空格...

' 创建/修改关键字值
rc = regsetvalueex（hkey, subkeyname, _
0, reg_sz, _
subkeyvalue, lenb（strconv（subkeyvalue, vbfromunicode)))

if （rc <> error_success) then goto createkeyerror ' 错误处理
'------------------------------------------------------------
'- 关闭注册表关键字...
'------------------------------------------------------------
rc = regclosekey（hkey) ' 关闭关键字

updatekey = true ' 返回成功
exit function ' 退出
createkeyerror:
updatekey = false ' 设置错误返回代码
rc = regclosekey（hkey) ' 试图关闭关键字
end function

'-------------------------------------------------------------------------------------------------
'sample usage - debug.print getkeyvalue（hkey_classes_root, "comctl.listviewctrl.1\clsid ", " ")
'-------------------------------------------------------------------------------------------------
public function getkeyvalue（keyroot as long, keyname as string, subkeyref as string) as string
dim i as long ' 循环计数器
dim rc as long ' 返回代码
dim hkey as long ' 处理打开的注册表关键字
dim hdepth as long '
dim skeyval as string
dim lkeyvaltype as long ' 注册表关键字数据类型
dim tmpval as string ' 注册表关键字的临时存储器
dim keyvalsize as long ' 注册表关键字变量尺寸

' 在 keyroot {hkey_local_machine...} 下打开注册表关键字
'------------------------------------------------------------
rc = regopenkeyex（keyroot, keyname, 0, key_all_access, hkey) ' 打开注册表关键字

if （rc <> error_success) then goto getkeyerror ' 处理错误...

tmpval = string$（1024, 0) ' 分配变量空间
keyvalsize = 1024 ' 标记变量尺寸

'------------------------------------------------------------
' 检索注册表关键字的值...
'------------------------------------------------------------
rc = regqueryvalueex（hkey, subkeyref, 0, _
lkeyvaltype, tmpval, keyvalsize) ' 获得/创建关键字的值

if （rc <> error_success) then goto getkeyerror ' 错误处理

tmpval = left$（tmpval, instr（tmpval, chr（0)) - 1)

'------------------------------------------------------------
' 决定关键字值的转换类型...
'------------------------------------------------------------
select case lkeyvaltype ' 搜索数据类型...
case reg_sz, reg_expand_sz ' 字符串注册表关键字数据类型
skeyval = tmpval ' 复制字符串的值
case reg_dword ' 四字节注册表关键字数据类型
for i = len（tmpval) to 1 step -1 ' 转换每一位
skeyval = skeyval + hex（asc（mid（tmpval, i, 1))) ' 一个字符一个字符地生成值。
next
skeyval = format$（ "&h " + skeyval) ' 转换四字节为字符串
end select

getkeyvalue = skeyval ' 返回值
rc = regclosekey（hkey) ' 关闭注册表关键字
exit function ' 退出

getkeyerror: ' 错误发生过后进行清除...
getkeyvalue = vbnullstring ' 设置返回值为空字符串
rc = regclosekey（hkey) ' 关闭注册表关键字
end function

发表于：2007-09-02 11:09:063楼得分:0

晕...发一堆这东西给我干嘛....问题我不知道哪里错了....- -

发表于：2007-09-03 13:32:124楼得分:0

你的错误:

请来一个工程师,却不给别人住的地方:)

ret = regqueryvalueex（hkey, "playback ", 0, reg_sz, byval name, 255)

这一句之前,再加一句:

name = space（255)

至于hotus发的代码,那可是好东西呀,你怎么一点都不领情:)

发表于：2007-09-04 08:39:475楼得分:0

调用 api，一定要给字符串分配内存。你这里出空值还是好的，有些情况下会程序崩溃。

方法有二：
1
dim name as string * 255
dim ret as long, hkey as long
ret = regopenkey（hkey_current_user, "software\microsoft\multimedia\sound mapper ", hkey)

2
dim name as string, ret as long, hkey as long
name = string（255, chr（0)) '或
'name = space（255)
ret = regopenkey（hkey_current_user, "software\microsoft\multimedia\sound mapper ", hkey)

发表于：2007-09-04 10:21:526楼得分:0

mark

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