• libxml2库使用示例

    解析一个名位noname.xml的文件：

    1. "1.0" standalone="no" ?>
    2. <Attributes>
    3.         <Attribute name="AcquireTime" type="EPICS_PV" source="$(P)$(R)cam1:AcquireTime" dbrtype="DBR_NATIVE"  description="Camera acquire time"/>
    4.         <Attribute name="FilePath" type="EPICS_PV" source="$(P)$(R)$(T)FilePath"  dbrtype="DBR_STRING" description="File Save Path"/>
    5. Attributes>

     解析以上文件的源文件：

    1. #include 
    2. #include 
    3. #include 
    4. #include 
    5. #include 
    6. #include 
    7. #include 
    8. #include 
    9. #include 
    10. #include 
    11. #include "NDAttribute.h"
    12. #include "NDAttributeList.h"
    13. #include "PVAttribute.h"
    14. #include 
    15.  
    16.  
    17. int main()
    18. {
    19.         MAC_HANDLE * macHandle;
    20.         char ** macPairs;
    21.         int status = 0;
    22.         std::ostringstream buff;
    23.         std::string buffer;
    24.         std::ifstream infile;
    25.         std::string fileName;
    26.         std::string macrodefs;
    27.         int bufferSize;
    28.  
    29.         fileName = "noname.xml";
    30.  
    31.         infile.open(fileName.c_str());
    32.  
    33.         buff << infile.rdbuf();
    34.         buffer = buff.str();
    35.  
    36.         printf("The name of a xml file to parse:\n ");
    37.         printf("fileName: %s\n", fileName.c_str());
    38.         printf("The file's content:\n");
    39.         printf("%s\n", buffer.c_str());
    40.         printf("--------------------------------------------------------------\n");
    41.  
    42.         macCreateHandle(&macHandle, 0);
    43.  
    44.         macrodefs = "P=BS:,R=SIM1:,T=TIFF1:";
    45.         printf("The macro defination:  %s\n", macrodefs.c_str());
    46.  
    47.         status = macParseDefns(macHandle, macrodefs.c_str() ,&macPairs);
    48.  
    49.         if (status < 0){
    50.                 printf("macParseDefns call failed\n");
    51.                 return -1;
    52.         }
    53.  
    54.         status = macInstallMacros(macHandle, macPairs);
    55.         if (status < 0){
    56.                 printf("macInstallMacros call failed\n");
    57.                 return -1;
    58.         }
    59.  
    60.         bufferSize = (int)(buffer.length() * 10);
    61.         char * tmpBuffer = (char *)malloc(sizeof(char ) * bufferSize);
    62.  
    63.         status = macExpandString(macHandle, buffer.c_str(), tmpBuffer, bufferSize);
    64.  
    65.         if (status < 0){
    66.                 printf("macExpandString call failed\n");
    67.                 free(tmpBuffer);
    68.                 free(macPairs);
    69.                 return -1;
    70.         }
    71.  
    72.         macrodefs = tmpBuffer;
    73.         free(tmpBuffer);
    74.         macDeleteHandle(macHandle);
    75.  
    76.         printf("Orignal file content: \n");
    77.         printf("'%s'\n\n", buffer.c_str());
    78.         printf("The expended file contenent\n");
    79.         printf("'%s'\n\n", macrodefs.c_str());
    80.  
    81.         const char *pName, *pSource, *pAttrType, *pDescription, *pDBRType;
    82.         xmlDocPtr doc;
    83.         xmlNode *Attr, *Attrs;
    84.  
    85.         doc = xmlReadMemory(macrodefs.c_str(), (int)macrodefs.length(), NULL , NULL, 0);
    86.  
    87.         if (doc == NULL) {
    88.                 printf("xmlReadMemory call failed\n");
    89.                 return -1;
    90.         }
    91.         Attrs = xmlDocGetRootElement(doc);
    92.  
    93.         if ((!xmlStrEqual(Attrs->name, (const xmlChar *)"Attributes")))
    94.         {
    95.                 printf("Cannot find the root 'Attriubtes\n'");
    96.                 return -1;
    97.         }
    98.  
    99.         printf("-----------------------------------------------------------------------\n");
    100.         printf("Parse the xml file: %s\n", fileName.c_str());
    101.         PVAttribute * pAttribute;
    102.         NDAttributeList * list = new NDAttributeList();
    103.  
    104.         for (Attr = xmlFirstElementChild(Attrs); Attr; Attr = xmlNextElementSibling(Attr)){
    105.                 pName = (const char *)xmlGetProp(Attr, (const xmlChar *)"name");
    106.                 if (!pName){
    107.                         printf("xmlGetProp '%s' call failed\n", "name");
    108.                         return -1;
    109.                 }
    110.  
    111.                 pDescription = (const char *)xmlGetProp(Attr, (const xmlChar *)"description");
    112.                 if (!pDescription) pDescription ="";
    113.  
    114.                 pSource = (const char *)xmlGetProp(Attr, (const xmlChar *)"source");
    115.                 if (!pSource){
    116.                         printf("xmlGetProp '%s' call failed\n", "source");
    117.                         return -1;
    118.                 }
    119.  
    120.                 pAttrType = (const char *)xmlGetProp(Attr, (const xmlChar *)"type");
    121.                 if (!pAttrType){
    122.                         printf("xmlGetProp '%s' call failed\n", "type");
    123.                         return -1;
    124.                 }
    125.  
    126.                 pDBRType = (const char *)xmlGetProp(Attr, (const xmlChar *)"dbrtype");
    127.                 if (!pDBRType){
    128.                         printf("xmlGetProp '%s' call failed\n", "dbrtype");
    129.                         return -1;
    130.                 }
    131.  
    132.  
    133.                 int dbrType = DBR_NATIVE;
    134.                 if (pDBRType) {
    135.                         if      (!strcmp(pDBRType, "DBR_CHAR"))
    136.                                 dbrType = DBR_CHAR;
    137.                         else if (!strcmp(pDBRType, "DBR_SHORT"))
    138.                                 dbrType = DBR_SHORT;
    139.                         else if (!strcmp(pDBRType, "DBR_ENUM"))
    140.                                 dbrType = DBR_ENUM;
    141.                         else if (!strcmp(pDBRType, "DBR_INT"))
    142.                                 dbrType = DBR_INT;
    143.                         else if (!strcmp(pDBRType, "DBR_LONG"))
    144.                                 dbrType = DBR_LONG;
    145.                         else if (!strcmp(pDBRType, "DBR_FLOAT"))
    146.                                 dbrType = DBR_FLOAT;
    147.                         else if (!strcmp(pDBRType, "DBR_DOUBLE"))
    148.                                 dbrType = DBR_DOUBLE;
    149.                         else if (!strcmp(pDBRType, "DBR_STRING"))
    150.                                 dbrType = DBR_STRING;
    151.                         else
    152.                                  dbrType = DBR_NATIVE;
    153.                 }
    154.  
    155.                 printf("name: %s\tsource: %s\ttype: %s\tdbrtype: %s\tdescription: %s\n", pName, pSource, pAttrType, pDBRType, pDescription);
    156.  
    157.                 pAttribute = new PVAttribute(pName, pDescription, pSource, dbrType );
    158.                 list->add(pAttribute);
    159.  
    160.         }
    161.  
    162.         epicsThreadSleep(1.0);
    163.         printf("-----------------------------------------------------------------------\n");
    164.         list->updateValues();
    165.         epicsThreadSleep(1.0);
    166.         printf("NDAttributeList and NDAttriubte's information: \n");
    167.         list->report(stdout, 20);
    168.  
    169.         return 0;
    170. }

    先用通道访问测试以上此处用到的EPICS过程变量：

    1. orangepi@orangepi5:~/C_program/host_program/hostApp$ caget BS:SIM1:cam1:AcquireTime
    2. BS:SIM1:cam1:AcquireTime   5
    3. orangepi@orangepi5:~/C_program/host_program/hostApp$ caget -S BS:SIM1:TIFF1:FilePath
    4. BS:SIM1:TIFF1:FilePath /home/test_gap

    编译以上程序，执行结果如下：

    1. orangepi@orangepi5:~/C_program/host_program/hostApp$ O.linux-aarch64/testXml
    2. The name of a xml file to parse:
    3.  fileName: noname.xml
    4. The file's content:
    7.         
    8.         
    11. --------------------------------------------------------------
    12. The macro defination:  P=BS:,R=SIM1:,T=TIFF1:
    13. Orignal file content:
    14. '"1.0" standalone="no" ?>
    16.         "AcquireTime" type="EPICS_PV" source="$(P)$(R)cam1:AcquireTime" dbrtype="DBR_NATIVE"  description="Camera acquire time"/>
    17.         "FilePath" type="EPICS_PV" source="$(P)$(R)$(T)FilePath"  dbrtype="DBR_STRING" description="File Save Path"/>
    19. '
    21. The expended file contenent
    22. '"1.0" standalone="no" ?>
    24.         "AcquireTime" type="EPICS_PV" source="BS:SIM1:cam1:AcquireTime" dbrtype="DBR_NATIVE"  description="Camera acquire time"/>
    25.         "FilePath" type="EPICS_PV" source="BS:SIM1:TIFF1:FilePath"  dbrtype="DBR_STRING" description="File Save Path"/>
    27. '
    29. -----------------------------------------------------------------------
    30. Parse the xml file: noname.xml
    31. name: AcquireTime       source: BS:SIM1:cam1:AcquireTime    type: EPICS_PV  dbrtype: DBR_NATIVE     description: Camera acquire time
    32. name: FilePath  source: BS:SIM1:TIFF1:FilePath      type: EPICS_PV  dbrtype: DBR_STRING     description: File Save Path
    33. -----------------------------------------------------------------------
    34. NDAttributeList and NDAttriubte's information:
    35.  
    36. NDAttributeList: address=0x556d1b5970:
    37.   number of attributes=2
    38.  
    39. NDAttribute, address=0x556d1b7f90:
    40.   name=AcquireTime
    41.   description=Camera acquire time
    42.   source type=2
    43.   source type string=NDAttrSourceEPICSPV
    44.   source=BS:SIM1:cam1:AcquireTime
    45.   dataType=NDAttrFloat64
    46.   value=5.000000
    47.   PVAttribute
    48.     dbrType=DBR_invalid
    49.     chanId=0x556d1bf3c0
    50.     eventId=0x7f80000b70
    51.  
    52. NDAttribute, address=0x556d1dff40:
    53.   name=FilePath
    54.   description=File Save Path
    55.   source type=2
    56.   source type string=NDAttrSourceEPICSPV
    57.   source=BS:SIM1:TIFF1:FilePath
    58.   dataType=NDAttrString
    59.   value=/home/test_gap
    60.   PVAttribute
    61.     dbrType=DBR_STRING
    62.     chanId=0x556d1bf3f8
    63.     eventId=0x7f80000b98
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  • 原文地址：https://blog.csdn.net/yuyuyuliang00/article/details/133792369