我有一个XML 文件，想把其标签取出来，拼成字符串。下面是test.xml文件和代码
<Document xmlns="urn:iso:std:iso:20022:tech:xsd:pacs.008.001.02">
<FIToFICstmrCdtTrf>
<GrpHdr>
<MsgId>0000000000000000000000000001</MsgId>
<CreDtTm>2001-12-17T09:30:47</CreDtTm>
<BtchBookg>true</BtchBookg>
<NbOfTxs>10</NbOfTxs>
<CtrlSum>30</CtrlSum>
<IntrBkSttlmDt>1967-08-13</IntrBkSttlmDt>
<SttlmInf>
<SttlmMtd>INDA</SttlmMtd>
</SttlmInf>
</GrpHdr>
<CdtTrfTxInf>
<PmtId>
<EndToEndId>111111111111111111111</EndToEndId>
<TxId>1021000133452010020200000001</TxId>
</PmtId>
<PmtTpInf>
<InstrPrty>HIGH</InstrPrty>
<CtgyPurp>
<Prtry>0010</Prtry>
</CtgyPurp>
</PmtTpInf>
<IntrBkSttlmAmt Ccy="CNY">11111111.1</IntrBkSttlmAmt>
<AccptncDtTm>2001-12-17T09:30:47</AccptncDtTm>
<ChrgBr>CRED</ChrgBr>
<Dbtr>
<Nm>test</Nm>
<CtctDtls>
<EmailAdr>test</EmailAdr>
</CtctDtls>
</Dbtr>
<DbtrAcct>
<Id>
<Othr>
