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//很多时候，为了避免多次访问/查询数据库重的数据或者便于察看，将需要的数据一次取出并写入xml文件
//通过查询条件m_condition 按照xmlmappath的模式/模板 将从库中的数据写到resultxml
//并返回记录条数
public int writexml(string m_condtion,string xmlmappath,string resultxml){
int recordnum=0;
string tablename = "table";
string tablecol = "*";
string sql = "select " + tablecol + " from " + tablename + " where " + m_condtion;
document mapdoc = null;
document datadoc = null;
document newdoc = null;
//开始准备工作
try {
documentbuilderfactory dbfactory = documentbuilderfactory.newinstance();
//create the documentbuilder
documentbuilder docbuilder = dbfactory.newdocumentbuilder();
//parse the file to create the document
mapdoc = docbuilder.parse(xmlmappath);
datadoc = docbuilder.newdocument();
//instantiate the new document
newdoc = docbuilder.newdocument();
} catch (exception e) {
system.out.println(e.getmassege());
}
//开始读取映射作用的template文件
element maproot = mapdoc.getdocumentelement();
node datanode = maproot.getelementsbytagname("data").item(0);
element dataelement = (element)datanode;
//create a new element called "data"
element dataroot = datadoc.createelement("data");
try {
/******** 这里创建一个连接conn,并创建statement
根据不同的数据源创建
********************************/
resultset resultset = stmt.query(sql);
//get the resultset information
resultsetmetadata resultmetadata = resultset.getmetadata();
int numcols = resultmetadata.getcolumncount();
log.write("db_to_xml:numcols:" + numcols);
while (resultset.next()) {
//create a new element called "row"
element rowel = datadoc.createelement("row");
//为了便于浏览和读，创建列数,以id为标记
string colname = "id";
string colval =integer.tostring(++recordnum);
element datael = datadoc.createelement(colname);
datael.appendchild(datadoc.createtextnode(colval));
rowel.appendchild(datael);
for (int i=1; i <= numcols; i++) {
colname = resultmetadata.getcolumnname(i);
//get the column value
colval = resultset.getstring(i);
//determine if the last column accessed was null
if (resultset.wasnull()) {
colval = "";
}
datael = datadoc.createelement(colname);
datael.appendchild(datadoc.createtextnode(colval));
rowel.appendchild(datael);
}
//add the row to the root element
dataroot.appendchild(rowel);
}
} catch (exception e) {
log.write(e.getmessage());
} finally {
log.write(" db_to_xml: closing connections...");
}
//add the root element to the document
datadoc.appendchild(dataroot);
node node1= maproot.getelementsbytagname("root").item(0);
element newrootinfo =(element)node1;
log.write("after got newrootinfo ...");
//retrieve the root and row information
string newrootname = newrootinfo.getattribute("name");
string newrowname= newrootinfo.getattribute("rowname");
nodelist newnodesmap = maproot.getelementsbytagname("element");
//create the final root element with the name from the mapping file
element newrootelement=null;
newrootelement = newdoc.createelement(newrootname);
nodelist oldrows = dataroot.getelementsbytagname("row");
for (int i=0; i < oldrows.getlength(); i++){
//retrieve each row in turn
element thisrow = (element)oldrows.item(i);
//create the new row
element newrow = newdoc.createelement(newrowname);
for (int j=0; j < newnodesmap.getlength(); j++) {
//for each node in the new mapping, retrieve the information
//first the new information...
element thiselement = (element)newnodesmap.item(j);
string newelementname = thiselement.getattribute("name");
//then the old information
element oldelement = (element)thiselement.getelementsbytagname("content").item(0);
string oldfield = oldelement.getfirstchild().getnodevalue();
//get the original values based on the mapping information
element oldvalueelement = (element)thisrow.getelementsbytagname(oldfield).item(0);
string oldvalue = oldvalueelement.getfirstchild().getnodevalue();
element newelement = newdoc.createelement(newelementname);
newelement.appendchild(newdoc.createtextnode(oldvalue));
nodelist newattributes = thiselement.getelementsbytagname("attribute");
for (int k=0; k < newattributes.getlength(); k++) {
//get the mapping information
element thisattribute = (element)newattributes.item(k);
string oldattributefield = thisattribute.getfirstchild().getnodevalue();
string newattributename = thisattribute.getattribute("name");
oldvalueelement = (element)thisrow.getelementsbytagname(oldattributefield).item(0);
string oldattributevalue = oldvalueelement.getfirstchild().getnodevalue();
newelement.setattribute(newattributename, oldattributevalue);
}
//add the new element to the new row
newrow.appendchild(newelement);
}
//add the new row to the root
newrootelement.appendchild(newrow);
}
//add the new root to the document
newdoc.appendchild(newrootelement);
//把生成的xml文档（newdoc）写到文件中(路径名为resultxml)
try{
transformerfactory tfactory = transformerfactory.newinstance();
transformer transformer = tfactory.newtransformer();
properties properties = transformer.getoutputproperties();
properties.setproperty(outputkeys.encoding, "gb2312");//iso8859_1，gb2312,utf-8
properties.setproperty(outputkeys.method, "xml");
properties.setproperty(outputkeys.version, "1.0");
properties.setproperty(outputkeys.indent, "yes");
transformer.setoutputproperties(properties);
domsource source = new domsource(newdoc);
streamresult result = new streamresult(new java.io.file(resultxml));
transformer.transform(source, result);
//生成xml文件 完成
} catch (exception e) {
system.out.println("xml file write:"+e.getmessage());
}
return recordnum;
}
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