如何将二进制流转换为文件？我的xml响应如下所示。
<env:Envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope/">
<env:Header/>
<env:Body>
<AttachmentRESP xmlns="http://xmlns.oracle.com/bpel/mobile/Leave">
<FileData xmlns="http://xmlns.oracle.com/bpel/mobile/Leave">iVBORw0KGgoAAAANSUhEUgAAAeAAAAMgCAIAAAB0wSZfAAAABGdBTUEAALGOfPtRkwAAACBjSFJN
AACHDwAAjA8AAP1SAACBQAAAfXkAAOmLAAA85QAAGcxzPIV3AAAKOWlDQ1BQaG90b3Nob3AgSUNDIHByb2ZpbGUAAEjHnZZ3VFTXFofPvXd6oc0wAlKG3rvAANJ7k15FYZgZYCgDDjM0sSGiAhFFRJoiSFDEgNFQJFZEsRAUVLAHJAgoMRhFVCxvRtaLrqy89/Ly++Osb+2z97n77L3PWhcAkqcvl5cGSwGQyhPwgzyc6RGRUXTsAIABHmCAKQBMVka6X7B7CBDJy82FniFyAl8EAfB6WLwCcNPQM4BOB/+fpFnp
fIHomAARm7M5GSwRF4g4JUuQLrbPipgalyxmGCVmvihBEcuJOWGRDT77LLKjmNmpPLaIxTmns1PZYu4V8bZMIUfEiK+ICzO5nCwR3xKxRoowlSviN+LYVA4zAwAUSWwXcFiJIjYRMYkfEuQi4uUA4EgJ
X3HcVyzgZAvEl3JJS8/hcxMSBXQdli7d1NqaQffkZKVwBALDACYrmcln013SUtOZvBwAFu/8WTLi2tJFRbY0tba0NDQzMv2qUP91829K3NtFehn4uWcQrf+L7a/80hoAYMyJarPziy2uCoDOLQDI3fti
0zgAgKSobx3Xv7oPTTwviQJBuo2xcVZWlhGXwzISF/QP/U+Hv6GvvmckPu6P8tBdOfFMYYqALq4bKy0lTcinZ6QzWRy64Z+H+B8H/nUeBkGceA6fwxNFhImmjMtLELWbx+YKuGk8Opf3n5r4D8P+pMW5
FonS+BFQY4yA1HUqQH7tBygKESDR+8Vd/6NvvvgwIH554SqTi3P/7zf9Z8Gl4iWDm/A5ziUohM4S8jMX98TPEqABAUgCKpAHykAd6ABDYAasgC1wBG7AG/iDEBAJVgMWSASpgA+yQB7YBApBMdgJ9oBq
UAcaQTNoBcdBJzgFzoNL4Bq4AW6D+2AUTIBnYBa8BgsQBGEhMkSB5CEVSBPSh8wgBmQPuUG+UBAUCcVCCRAPEkJ50GaoGCqDqqF6qBn6HjoJnYeuQIPQXWgMmoZ+h97BCEyCqbASrAUbwwzYCfaBQ+BV
cAK8Bs6FC+AdcCXcAB+FO+Dz8DX4NjwKP4PnEIAQERqiihgiDMQF8UeikHiEj6xHipAKpAFpRbqR</FileData>
</AttachmentRESP>
</env:Body>
</env:Envelope>
这是一个图像文件。我是以上述格式从服务器收到的。但是如何将这种格式转换为图像？