如何获取下面这个String 字符串中的 节点和值
String xml="
XML=<?xml version="1.0" encoding="UTF-8"?>
<tns:GetMeterReading xmlns:obj="http://iec.ch/TC57/2011/EndDeviceAssets" xmlns:tns="http://iec.ch/TC57/2011/EndDeviceAssetsMessage" xmlns:msg="http://iec.ch/TC57/2011/schema/message" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://iec.ch/TC57/2011/EndDeviceAssetsMessage MeterAssetConfig_Format.xsd">
<tns:Header>
<msg:Verb>report</msg:Verb>
<msg:Noun/>
<msg:Timestamp>
13698157289
0000000</msg:Timestamp>
<msg:MessageID/>
</tns:Header>
<tns:Reply>
<msg:Result>OK</msg:Result>
</tns:Reply>
<tns:Payload>
<tns:MeterReadings>
<obj:MeterReading>
<obj:MeterAsset>
<obj:mRID>10010002071000</obj:mRID>
<obj:LocalComPort>
<obj:mRID>20050000000001</obj:mRID>
</obj:LocalComPort>
</obj:MeterAsset>
<obj:IntervalBlocks>
<obj:IntervalReadings>
<obj:timeStamp>2016-03-17 18:45:00</obj:timeStamp>
<obj:value>4783.87</obj:value>
</obj:IntervalReadings>
<obj:ReadingType>
<obj:mRID>10040000000001</obj:mRID>
</obj:ReadingType>
</obj:IntervalBlocks>
<obj:IntervalBlocks>
<obj:IntervalReadings>
<obj:timeStamp>2016-03-17 18:45:00</obj:timeStamp>
<obj:value>338.333</obj:value>
</obj:IntervalReadings>
<obj:ReadingType>
<obj:mRID>10040000000031</obj:mRID>
</obj:ReadingType>
</obj:IntervalBlocks>
<obj:IntervalBlocks>
<obj:IntervalReadings>
<obj:timeStamp>2016-03-17 18:45:00</obj:timeStamp>
<obj:value>181.667</obj:value>
</obj:IntervalReadings>
<obj:ReadingType>
<obj:mRID>10040000000032</obj:mRID>
</obj:ReadingType>
</obj:IntervalBlocks>
<obj:IntervalBlocks>
<obj:IntervalReadings>
<obj:timeStamp>2016-03-17 18:45:00</obj:timeStamp>
<obj:value>0.0</obj:value>
</obj:IntervalReadings>
<obj:ReadingType>
<obj:mRID>10040000000033</obj:mRID>
</obj:ReadingType>
</obj:IntervalBlocks>
<obj:IntervalBlocks>
<obj:IntervalReadings>
<obj:timeStamp>2016-03-17 18:45:00</obj:timeStamp>
<obj:value>156.667</obj:value>
</obj:IntervalReadings>
<obj:ReadingType>
<obj:mRID>10040000000034</obj:mRID>
</obj:ReadingType>
</obj:IntervalBlocks>
<obj:IntervalBlocks>
<obj:IntervalReadings>
<obj:timeStamp>2016-03-17 18:45:00</obj:timeStamp>
<obj:value>55.0</obj:value>
</obj:IntervalReadings>
<obj:ReadingType>
<obj:mRID>10040000000035</obj:mRID>
</obj:ReadingType>
</obj:IntervalBlocks>
<obj:IntervalBlocks>
<obj:IntervalReadings>
<obj:timeStamp>2016-03-17 18:45:00</obj:timeStamp>
<obj:value>71.667</obj:value>
</obj:IntervalReadings>
<obj:ReadingType>
<obj:mRID>10040000000036</obj:mRID>
</obj:ReadingType>
</obj:IntervalBlocks>
<obj:IntervalBlocks>
<obj:IntervalReadings>
<obj:timeStamp>2016-03-17 18:45:00</obj:timeStamp>
<obj:value>0.0</obj:value>
</obj:IntervalReadings>
<obj:ReadingType>
<obj:mRID>10040000000037</obj:mRID>
</obj:ReadingType>
</obj:IntervalBlocks>
<obj:IntervalBlocks>
<obj:IntervalReadings>
<obj:timeStamp>2016-03-17 18:45:00</obj:timeStamp>
<obj:value>126.667</obj:value>
</obj:IntervalReadings>
<obj:ReadingType>
<obj:mRID>10040000000038</obj:mRID>
</obj:ReadingType>
</obj:IntervalBlocks>
<obj:IntervalBlocks>
<obj:IntervalReadings>
<obj:timeStamp>2016-03-17 18:45:00</obj:timeStamp>
<obj:value>99.0</obj:value>
</obj:IntervalReadings>
<obj:ReadingType>
<obj:mRID>10040000000039</obj:mRID>
</obj:ReadingType>
</obj:IntervalBlocks>
<obj:IntervalBlocks>
<obj:IntervalReadings>
<obj:timeStamp>2016-03-17 18:45:00</obj:timeStamp>
<obj:value>0.0</obj:value>
</obj:IntervalReadings>
<obj:ReadingType>
<obj:mRID>10040000000040</obj:mRID>
</obj:ReadingType>
</obj:IntervalBlocks>
<obj:IntervalBlocks>
<obj:IntervalReadings>
<obj:timeStamp>2016-03-17 18:45:00</obj:timeStamp>
<obj:value>101.4</obj:value>
</obj:IntervalReadings>
<obj:ReadingType>
<obj:mRID>10040000000041</obj:mRID>
</obj:ReadingType>
</obj:IntervalBlocks>
<obj:IntervalBlocks>
<obj:IntervalReadings>
<obj:timeStamp>2016-03-17 18:45:00</obj:timeStamp>
<obj:value>1.978</obj:value>
</obj:IntervalReadings>
<obj:ReadingType>
<obj:mRID>10040000000042</obj:mRID>
</obj:ReadingType>
</obj:IntervalBlocks>
<obj:IntervalBlocks>
<obj:IntervalReadings>
<obj:timeStamp>2016-03-17 18:45:00</obj:timeStamp>
<obj:value>1.987</obj:value>
</obj:IntervalReadings>
<obj:ReadingType>
<obj:mRID>10040000000043</obj:mRID>
</obj:ReadingType>
</obj:IntervalBlocks>
<obj:IntervalBlocks>
<obj:IntervalReadings>
<obj:timeStamp>2016-03-17 18:45:00</obj:timeStamp>
<obj:value>1.997</obj:value>
</obj:IntervalReadings>
<obj:ReadingType>
<obj:mRID>10040000000044</obj:mRID>
</obj:ReadingType>
</obj:IntervalBlocks>
<obj:IntervalBlocks>
<obj:IntervalReadings>
<obj:timeStamp>2016-03-17 18:45:00</obj:timeStamp>
<obj:value>0.99</obj:value>
</obj:IntervalReadings>
<obj:ReadingType>
<obj:mRID>10040000000049</obj:mRID>
</obj:ReadingType>
</obj:IntervalBlocks>
</obj:MeterReading>
</tns:MeterReadings>
</tns:Payload>
</tns:GetMeterReading>
"