该模式下， CMake 会搜索 <lowercasePackageName>-config.cmake 文件或 <PackageName>Config.cmake 文件。如果 find_package 命令中指定了具体的版本，也会搜索 <lowercasePackageName>-config-version.cmake 或 <PackageName>ConfigVersion.cmake 文件，因此配置模式下通常会提供配置文件和版本文件（注意形式上要保持一致），并且作为包的一部分一起提供给使用者。
缺丛 同样的，当 find_package 调用返回时，一系列跟包相关的变量也会提供给调用者。例如 <PackageName>_FOUND 标识包是否找到、 <PackageName>_DIR 变量用于指示包配置文件所在的位置。实际上，返回的变量并没有特别的限制，但是还是建议遵循 模块模式 的标准变量名称的命名规则。
一个配置文件方式提供的包由 包配置文件 （必须包含，名为 <lowercasePackageName>-config.cmake 文件或 <PackageName>Config.cmake ）和 包版本文件 （可选，名为 <lowercasePackageName>-config-version.cmake 或 <PackageName>ConfigVersion.cmake ）组成。配置文件和版本文件的命名要配对出现，也就是：
或者是：
仍然是以我们自己编写的 mymath 库为例，假设 mymath 库提供了如下的文件：
mymathConfig.cmake 文件有两种方式可以生成：
可以参考 Cmake命令之find_package介绍 的伏早樱 4.1 章节查看 .cmake 文件的搜索路径，我们的例子将在 find_package 中通过 PATHS 来指定。
find_package 找到一个配置文件后，会尝试去查找版本文件。版本文件的主要作用是用来验证包的版本是否与 find_package 命令中指定的版本信息匹配。如果匹配的话，就会使用配置文件中的内容，否则会忽略配置文件中的内容。
和配置文件一样，版本文件也有两种方式生成：
当 find_package 命令在加载版本文件时，首先会通过从 find_package 中得到的版本信息设置睁毁如下变量，用于版本文件中版本对比：
在版本文件中可以使用上述变量来检查版本的兼容性、版本是否匹配，并设置如下变量作为返回结果：
find_package 会检查上述变量，如果版本匹配成功，那么 find_package 会返回如下变量给调用者：
mymath 库的 CMakeLists.txt 内容如下：
在命令行中执行 cmake . 和 make 生成 libmymath.a 库。
mymath 库及其提供的 .cmake 配置文件见本文的第二章节。下面来编写测试文件：
在命令行中执行 cmake . 和 make 生成 test 可执行文件并执行 ./test ，对应的输出结果如下（摘取重要部分呈现）：
在go语言中使用viper之类的库很方便的处理yaml配置文件，但是在c语言中就比较麻烦，经过一番思索和借助强大的github,发现了一个libyaml c库，但是网上的例子都比较麻烦，而且比较繁琐，就想法作了一个相对比较容易配置的解析应用，可以简单地类似viper 的模式进行配置实现不同的配置文件读取。如你的配置文件很复杂请按格式修改KeyValue 全山裤局变量，欢迎大家一起完善
库请自行下扒世载 GitHub - yaml/libyaml: Canonical source repository for LibYAML
直接上代码
yaml示例文件
%YAML 1.1
---
mqtt:
subtopic: "Control/#"
pubtopic: "bbt"
qos: 1
serveraddress: "tcp://192.168.0.25:1883"
clientid: "kvm_test"
writelog: false
writetodisk: false
outputfile: "./receivedMessages.txt"
hearttime: 30
#ifndef __CONFIG_H__
#define __CONFIG_H__
#ifdef __cplusplus
extern "C" {
#endif
/************************/
/* Minimum YAML version */
/************************/
#define YAML_VERSION_MAJOR 1
#define YAML_VERSION_MINOR 1
#define STRUCT_TYPE_NAME 100
#define INT_TYPE_NAME 101
#define STRING_TYPE_NAME 102
#define BOOL_TYPE_NAME 103
#define FLOAT_TYPE_NAME 104
#define MAP_TYPE_NAME 105
#define LIST_TYPE_NAME 106
typedef struct{
char *key
void *value
int valuetype
char *parent
}KeyValue,*pKeyValue
#ifdef __cplusplus
}
#endif
#endif
#include
#include
#include
#include
#include
#include
#include
#include "config.h"
typedef struct {
char *SUBTOPIC//string `yaml:"subtopic" mapstructure:"subtopic"` //"topic1"
char *PUBTOPIC//string `yaml:"pubtopic" mapstructure:"pubtopic"`
int QOS//byte `yaml:"qos" mapstructure:"qos"` //1
char *SERVERADDRESS//string `yaml:"serveraddress" mapstructure:"serveraddress"` //= "tcp://mosquitto:1883"
char *CLIENTID//string `yaml:"clientid" mapstructure:"clientid"` //= "mqtt_subscriber"
int HEARTTIME//int `yaml:"hearttime" mapstructure:"hearttime"春唯肢`
// CommandLocalPath string `yam:"commanlocalpath"`
}mqttSection,*pmqttSection
typedef struct {
mqttSection Mqtt// `yaml:"mqtt" mapstructure:"mqtt"`
// KVM kvmSection `yaml:"kvm" mapstructure:"kvm"`
}ConfigT
ConfigT config
static KeyValue webrtcconfig[]={
{"mqtt",&config,STRUCT_TYPE_NAME,NULL},
{"subtopic",&(config.Mqtt.SUBTOPIC),STRING_TYPE_NAME,"mqtt"},
{"pubtopic",&(config.Mqtt.PUBTOPIC),STRING_TYPE_NAME,"mqtt"},
{"qos",&(config.Mqtt.QOS),INT_TYPE_NAME,"mqtt"},
{"serveraddress",&(config.Mqtt.SERVERADDRESS),STRING_TYPE_NAME,"mqtt"},
{"clientid",&(config.Mqtt.CLIENTID),STRING_TYPE_NAME,"mqtt"},
{"hearttime",&(config.Mqtt.HEARTTIME),INT_TYPE_NAME,"mqtt"},
{NULL,NULL,0,NULL},
}
int printConfig(ConfigT * pconfig){
if(pconfig==NULL) return -1
printf("mqtt:r ")
if(pconfig->Mqtt.SUBTOPIC!=NULL) {printf("subtopic: %sr ",pconfig->Mqtt.SUBTOPIC)}
if(pconfig->Mqtt.SUBTOPIC!=NULL) {printf("pubtopic: %sr ",pconfig->Mqtt.PUBTOPIC)}
printf("qos: %dr ",config.Mqtt.QOS)
if(pconfig->Mqtt.SERVERADDRESS!=NULL) {printf("serveraddress: %sr ",pconfig->Mqtt.SERVERADDRESS)}
if(pconfig->Mqtt.CLIENTID!=NULL) {printf("clientid: %sr ",pconfig->Mqtt.CLIENTID)}
printf("hearttime: %dr ",config.Mqtt.HEARTTIME)
}
int freeConfig(ConfigT * pconfig){
if(pconfig==NULL) return -1
if(pconfig->Mqtt.SERVERADDRESS!=NULL) {free(pconfig->Mqtt.SERVERADDRESS)}
if(pconfig->Mqtt.CLIENTID!=NULL) {free(pconfig->Mqtt.CLIENTID)}
if(pconfig->Mqtt.SUBTOPIC!=NULL) {free(pconfig->Mqtt.SUBTOPIC)}
}
char currentkey[100]
void getvalue(yaml_event_t event,pKeyValue *ppconfigs){
char *value = (char *)event.data.scalar.value
pKeyValue pconfig=*ppconfigs
char *pstringname
while(pconfig->key!=NULL){
if(currentkey[0]!=0){
if(!strcmp(currentkey,pconfig->key))
{
switch(pconfig->valuetype){
case STRING_TYPE_NAME:
pstringname=strdup(value)
printf("get string value %sr ",pstringname)
*((char**)pconfig->value)=pstringname
memset(currentkey, 0, sizeof(currentkey))
break
case INT_TYPE_NAME:
*((int*)(pconfig->value))=atoi(value)
memset(currentkey, 0, sizeof(currentkey))
break
case BOOL_TYPE_NAME:
if(!strcmp(value,"true")) *((bool*)(pconfig->value))=true
else *((bool*)(pconfig->value))=false
memset(currentkey, 0, sizeof(currentkey))
break
case FLOAT_TYPE_NAME:
*((float*)(pconfig->value))=atof(value)
memset(currentkey, 0, sizeof(currentkey))
break
case STRUCT_TYPE_NAME:
case MAP_TYPE_NAME:
case LIST_TYPE_NAME:
memset(currentkey, 0, sizeof(currentkey))
strncpy(currentkey,value,strlen(value))
break
default:
break
}
break
}
//continue
}else{
if(!strcmp(value,pconfig->key)){
strncpy(currentkey,pconfig->key,strlen(pconfig->key))
break
}
}
pconfig++
}
}
int Load_YAML_Config( char *yaml_file, KeyValue *(configs[]) )
{
struct stat filecheck
yaml_parser_t parser
yaml_event_t event
bool done = 0
unsigned char type = 0
unsigned char sub_type = 0
if (stat(yaml_file, &filecheck) != false )
{
printf("[%s, line %d] Cannot open configuration file '%s'! %s", __FILE__, __LINE__, yaml_file, strerror(errno) )
return -1
}
FILE *fh = fopen(yaml_file, "r")
if (!yaml_parser_initialize(&parser))
{
printf("[%s, line %d] Failed to initialize the libyaml parser. Abort!", __FILE__, __LINE__)
return -1
}
if (fh == NULL)
{
printf("[%s, line %d] Failed to open the configuration file '%s' Abort!", __FILE__, __LINE__, yaml_file)
return -1
}
memset(currentkey, 0, sizeof(currentkey))
/* Set input file */
yaml_parser_set_input_file(&parser, fh)
while(!done)
{
if (!yaml_parser_parse(&parser, &event))
{
/* Useful YAML vars: parser.context_mark.line+1, parser.context_mark.column+1, parser.problem, parser.problem_mark.line+1, parser.problem_mark.column+1 */
printf( "[%s, line %d] libyam parse error at line %ld in '%s'", __FILE__, __LINE__, parser.problem_mark.line+1, yaml_file)
}
if ( event.type == YAML_DOCUMENT_START_EVENT )
{
//yaml file first line is version
//%YAML 1.1
//---
yaml_version_directive_t *ver = event.data.document_start.version_directive
if ( ver == NULL )
{
printf( "[%s, line %d] Invalid configuration file. Configuration must start with "%%YAML 1.1"", __FILE__, __LINE__)
}
int major = ver->major
int minor = ver->minor
if (! (major == YAML_VERSION_MAJOR &&minor == YAML_VERSION_MINOR) )
{
printf( "[%s, line %d] Configuration has a invalid YAML version. Must be 1.1 or above", __FILE__, __LINE__)
return -1
}
}
else if ( event.type == YAML_STREAM_END_EVENT )
{
done = true
}
else if ( event.type == YAML_MAPPING_END_EVENT )
{
sub_type = 0
}
else if ( event.type == YAML_SCALAR_EVENT )
{
getvalue(event,configs)
}
}
return 0
}
int main(int argc, char *argv[]){
pKeyValue pconfig=&webrtcconfig[0]
Load_YAML_Config("../../etc/kvmagent.yml",&pconfig)
printConfig(&config)
freeConfig(&config)
}
应用程序配置文件（App.config）是标准的 XML 文件，XML 标记和属性是区分大小写的。它是可以按需要更改的，厅粗开发人员可以扮让镇使用配置文件来更改设置，而不必重编译应用程序。对于一个config文件：
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<appSettings>
<add key="ServerIP" value="127.0.0.1"></add>
<add key="DataBase" value="WarehouseDB"></add>
<add key="user" value="sa"></add>
<add key="password" value="sa"></add>
</appSettings>
</configuration>
对config配置文件的读写类：
using System
using System.Collections.Generic
using System.Linq
using System.Text
using System.Text.RegularExpressions
using System.Configuration
using System.ServiceModel
using System.ServiceModel.Configuration
namespace NetUtilityLib
{
public static class ConfigHelper
{
//依据连接串名字connectionName返回数据连接字符串
public static string GetConnectionStringsConfig(string connectionName)
{
//指定config文件读取
string file = System.Windows.Forms.Application.ExecutablePath
System.Configuration.Configuration config = ConfigurationManager.OpenExeConfiguration(file)
string connectionString =
config.ConnectionStrings.ConnectionStrings[connectionName].ConnectionString.ToString()
return connectionString
}
///<summary>
///更新连接字符串
///滑漏</summary>
///<param name="newName">连接字符串名称</param>
///<param name="newConString">连接字符串内容</param>
///<param name="newProviderName">数据提供程序名称</param>
public static void UpdateConnectionStringsConfig(string newName, string newConString, string newProviderName)
{
//指定config文件读取
string file = System.Windows.Forms.Application.ExecutablePath
Configuration config = ConfigurationManager.OpenExeConfiguration(file)
bool exist = false//记录该连接串是否已经存在
//如果要更改的连接串已经存在
if (config.ConnectionStrings.ConnectionStrings[newName] != null)
{
exist = true
}
// 如果连接串已存在，首先删除它
if (exist)
{
config.ConnectionStrings.ConnectionStrings.Remove(newName)
}
//新建一个连接字符串实例
ConnectionStringSettings mySettings =
new ConnectionStringSettings(newName, newConString, newProviderName)
// 将新的连接串添加到配置文件中.
config.ConnectionStrings.ConnectionStrings.Add(mySettings)
// 保存对配置文件所作的更改
config.Save(ConfigurationSaveMode.Modified)
// 强制重新载入配置文件的ConnectionStrings配置节
ConfigurationManager.RefreshSection("ConnectionStrings")
}
///<summary>
///返回*.exe.config文件中appSettings配置节的value项
///</summary>
///<param name="strKey"></param>
///<returns></returns>
public static string GetAppConfig(string strKey)
{
string file = System.Windows.Forms.Application.ExecutablePath
Configuration config = ConfigurationManager.OpenExeConfiguration(file)
foreach (string key in config.AppSettings.Settings.AllKeys)
{
if (key == strKey)
{
return config.AppSettings.Settings[strKey].Value.ToString()
}
}
return null
}
///<summary>
///在*.exe.config文件中appSettings配置节增加一对键值对
///</summary>
///<param name="newKey"></param>
///<param name="newValue"></param>
public static void UpdateAppConfig(string newKey, string newValue)
{
string file = System.Windows.Forms.Application.ExecutablePath
Configuration config = ConfigurationManager.OpenExeConfiguration(file)
bool exist = false
foreach (string key in config.AppSettings.Settings.AllKeys)
{
if (key == newKey)
{
exist = true
}
}
if (exist)
{
config.AppSettings.Settings.Remove(newKey)
}
config.AppSettings.Settings.Add(newKey, newValue)
config.Save(ConfigurationSaveMode.Modified)
ConfigurationManager.RefreshSection("appSettings")
}
// 修改system.serviceModel下所有服务终结点的IP地址
public static void UpdateServiceModelConfig(string configPath, string serverIP)
{
Configuration config = ConfigurationManager.OpenExeConfiguration(configPath)
ConfigurationSectionGroup sec = config.SectionGroups["system.serviceModel"]
ServiceModelSectionGroup serviceModelSectionGroup = sec as ServiceModelSectionGroup
ClientSection clientSection = serviceModelSectionGroup.Client
foreach (ChannelEndpointElement item in clientSection.Endpoints)
{
string pattern = @"\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b"
string address = item.Address.ToString()
string replacement = string.Format("{0}", serverIP)
address = Regex.Replace(address, pattern, replacement)
item.Address = new Uri(address)
}
config.Save(ConfigurationSaveMode.Modified)
ConfigurationManager.RefreshSection("system.serviceModel")
}
// 修改applicationSettings中App.Properties.Settings中服务的IP地址
public static void UpdateConfig(string configPath, string serverIP)
{
Configuration config = ConfigurationManager.OpenExeConfiguration(configPath)
ConfigurationSectionGroup sec = config.SectionGroups["applicationSettings"]
ConfigurationSection configSection = sec.Sections["DataService.Properties.Settings"]
ClientSettingsSection clientSettingsSection = configSection as ClientSettingsSection
if (clientSettingsSection != null)
{
SettingElement element1 = clientSettingsSection.Settings.Get("DataService_SystemManagerWS_SystemManagerWS")
if (element1 != null)
{
clientSettingsSection.Settings.Remove(element1)
string oldValue = element1.Value.ValueXml.InnerXml
element1.Value.ValueXml.InnerXml = GetNewIP(oldValue, serverIP)
clientSettingsSection.Settings.Add(element1)
}
SettingElement element2 = clientSettingsSection.Settings.Get("DataService_EquipManagerWS_EquipManagerWS")
if (element2 != null)
{
clientSettingsSection.Settings.Remove(element2)
string oldValue = element2.Value.ValueXml.InnerXml
element2.Value.ValueXml.InnerXml = GetNewIP(oldValue, serverIP)
clientSettingsSection.Settings.Add(element2)
}
}
config.Save(ConfigurationSaveMode.Modified)
ConfigurationManager.RefreshSection("applicationSettings")
}
private static string GetNewIP(string oldValue, string serverIP)
{
string pattern = @"\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b"
string replacement = string.Format("{0}", serverIP)
string newvalue = Regex.Replace(oldValue, pattern, replacement)
return newvalue
}
}
}
测试代码如下：
class Program
{
static void Main(string[] args)
{
try
{
//string file = System.Windows.Forms.Application.ExecutablePath + ".config"
//string file1 = AppDomain.CurrentDomain.SetupInformation.ConfigurationFile
string serverIP = ConfigHelper.GetAppConfig("ServerIP")
string db = ConfigHelper.GetAppConfig("DataBase")
string user = ConfigHelper.GetAppConfig("user")
string password = ConfigHelper.GetAppConfig("password")
Console.WriteLine(serverIP)
Console.WriteLine(db)
Console.WriteLine(user)
Console.WriteLine(password)
ConfigHelper.UpdateAppConfig("ServerIP", "192.168.1.11")
string newIP = ConfigHelper.GetAppConfig("ServerIP")
Console.WriteLine(newIP)
Console.ReadKey()
}
catch (Exception ex)
{
Console.WriteLine(ex.Message)
}
}
}
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