对XML和YAML文件实现I/O操作

发布时间：2020-12-15 22:57:41 所属栏目：百科来源：网络整理

导读：CPOY FROM：http://blog.csdn.net/yang_xian521/article/details/6897684?reload 1. XML、YAML文件的打开和关闭 XMLYAML文件在OpenCV中的数据结构为FileStorage，打开操作例如： [cpp] view plain copy stringfilename= "I.xml" ; FileStoragefs(filename,F

CPOY FROM：http://blog.csdn.net/yang_xian521/article/details/6897684?reload

1. XML、YAML文件的打开和关闭

XMLYAML文件在OpenCV中的数据结构为FileStorage，打开操作例如：

[cpp] 
   view plain 
   copy 
    
   
 stringfilename="I.xml";
 FileStoragefs(filename,FileStorage::WRITE);
 ...
 fs.open(filename,FileStorage::READ);

文件关闭操作会在FileStorage结构销毁时自动进行，但也可调用如下函数实现

copy

fs.release();

2.文本和数字的输入和输出

写入文件使用 << 运算符，例如：

copy

fs<<"iterationNr"<<100;

读取文件，使用 >> 运算符，例如 copy

intitNr;

fs["iterationNr"]>>itNr;
itNr=(int)fs["iterationNr"];

3. OpenCV数据结构的输入和输出，和基本的C++形式相同

copy 
    
   

MatR=Mat_<uchar>::eye(3,3),

T=Mat_<double>::zeros(3,1);
fs<<"R"<<R;//Writecv::Mat
fs<<"T"<<T;
fs["R"]>>R;//Readcv::Mat
fs["T"]>>T;

4. vector（arrays）和 maps的输入和输出 vector要注意在第一个元素前加上“[”，在最后一个元素前加上"]"。例如：

copy

fs<<"strings"<<"[";//text-stringsequence

fs<<"image1.jpg"<<"Awesomeness"<<"baboon.jpg";
fs<<"]";//closesequence

对于map结构的操作使用的符号是"{"和"}"，例如： copy

fs<<"Mapping";//text-mapping

fs<<"{"<<"One"<<1;
fs<<"Two"<<2<<"}";

读取这些结构的时候，会用到FileNode和FileNodeIterator数据结构。对FileStorage类的[]操作符会返回FileNode数据类型，对于一连串的node，可以使用FileNodeIterator结构，例如： copy

FileNoden=fs["strings"];//Readstringsequence-Getnode

if(n.type()!=FileNode::SEQ)
{
cerr<<"stringsisnotasequence!FAIL"<<endl;
return1;
}
FileNodeIteratorit=n.begin(),it_end=n.end();//Gothroughthenode
for(;it!=it_end;++it)
cout<<(string)*it<<endl;

5. 读写自己的数据结构这部分比较复杂，参考最后的实例中的MyData结构自己领悟吧

最后，我这里上一个实例，供大家参考。

源文件里填入如下代码：

copy

#include<opencv2/core/core.hpp>

#include<iostream>
#include<string>
usingnamespacecv;
namespacestd;
voidhelp(char**av)
cout<<endl
<<av[0]<<"showstheusageoftheOpenCVserializationfunctionality."<<endl
<<"usage:"<<endl
<<av[0]<<"outputfile.yml.gz"<<endl
<<"TheoutputfilemaybeeitherXML(xml)orYAML(yml/yaml).Youcanevencompressitby"
<<"specifyingthisinitsextensionlikexml.gzyaml.gzetc..."<<endl
<<"WithFileStorageyoucanserializeobjectsinOpenCVbyusingthe<<and>>operators"<<endl
<<"Forexample:-createaclassandhaveitserialized"<<endl
<<"-useittoreadandwritematrices."<<endl;
}
classMyData
{
public:
MyData():A(0),X(0),id()
{}
explicitMyData(int):A(97),X(CV_PI),id("mydata1234")//explicittoavoidimplicitconversion
voidwrite(FileStorage&fs)const//Writeserializationforthisclass
fs<<"{"<<"A"<<A<<"X"<<X<<"id"<<id<<"}";
voidread(constFileNode&node)//Readserializationforthisclass
A=(int)node["A"];
X=(double)node["X"];
id=(string)node["id"];
public://DataMembers
intA;
doubleX;
stringid;
};
//ThesewriteandreadfunctionsmustbedefinedfortheserializationinFileStoragetowork
voidwrite(FileStorage&fs,conststd::string&,153); background-color:inherit; font-weight:bold">constMyData&x)
x.write(fs);
constFileNode&node,MyData&x,153); background-color:inherit; font-weight:bold">constMyData&default_value=MyData()){
if(node.empty())
x=default_value;
else
x.read(node);
//Thisfunctionwillprintourcustomclasstotheconsole
ostream&operator<<(ostream&out,constMyData&m)
out<<"{id="<<m.id<<",";
out<<"X="<<m.X<<",";
out<<"A="<<m.A<<"}";
returnout;
intmain(intac,char**av)
if(ac!=2)
help(av);
return1;
stringfilename=av[1];
{//write
MatR=Mat_<uchar>::eye(3,
MyDatam(1);
FileStoragefs(filename,FileStorage::WRITE);
fs<<"iterationNr"<<100;
fs<<"strings"<<"[";//text-stringsequence
fs<<"image1.jpg"<<"Awesomeness"<<"baboon.jpg";
fs<<"]";//closesequence
fs<<"Mapping";//text-mapping
fs<<"{"<<"One"<<1;
fs<<"Two"<<2<<"}";
fs<<"R"<<R;//cv::Mat
fs<<"T"<<T;
fs<<"MyData"<<m;//yourowndatastructures
fs.release();//explicitclose
cout<<"WriteDone."<<endl;
{//read
cout<<endl<<"Reading:"<<endl;
FileStoragefs;
intitNr;
//fs["iterationNr"]>>itNr;
itNr=(int)fs["iterationNr"];
cout<<itNr;
if(!fs.isOpened())
cerr<<"Failedtoopen"<<filename<<endl;
FileNoden=fs["strings"]; FileNodeIteratorit=n.begin(),0); background-color:inherit">//Gothroughthenode
for(;it!=it_end;++it)
cout<<(string)*it<<endl;
n=fs["Mapping"];//Readmappingsfromasequence
cout<<"Two"<<(int)(n["Two"])<<";";
cout<<"One"<<(int)(n["One"])<<endl<<endl;
MyDatam;
MatR,T;
fs["T"]>>T;
fs["MyData"]>>m;//Readyourownstructure_
cout<<endl
<<"R="<<R<<endl;
cout<<"T="<<T<<endl<<endl;
cout<<"MyData="<<endl<<m<<endl<<endl;
//Showdefaultbehaviorfornonexistingnodes
cout<<"AttempttoreadNonExisting(shouldinitializethedatastructurewithitsdefault).";
fs["NonExisting"]>>m;
cout<<endl<<"NonExisting="<<endl<<m<<endl;
<<"Tip:Openup"<<filename<<"withatexteditortoseetheserializeddata."<<endl;
return0;
}

编译后，在命令行进入到文件目录，执行test test.xml，运行结果如下，生成一个test . xml文件，内容如下：

[html] 
   copy

<?xmlversion="1.0"?>

-<opencv_storage>
iterationNr>100</>
strings>image1.jpgAwesomenessbaboon.jpg -MappingOne>1Two>2Rtype_id="opencv-matrix"rows>3colsdt>udata>100010001RTtype_id="opencv-matrix">d>0.0.0.TMyDataA>97X>3.1415926535897931e+000id>mydata1234>

（编辑：李大同）

【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!