写在前面，不想看分析的直接看结果：总结来说就是你使用了Decimal128的Bson类型，但是你的mongodb版本低于3.4版本，不支持这个类型。
在执行插入语句的时候，报错，如下：
2018-07-04 18:14:23.660 ERROR com.mongodb.MongoSocketReadException: Prematurely reached end of stream
com.mongodb.MongoSocketReadException: Prematurely reached end of stream
at com.mongodb.connection.SocketStream.read(SocketStream.java:88)
at com.mongodb.connection.InternalStreamConnection.receiveResponseBuffers(InternalStreamConnection.java:494)
at com.mongodb.connection.InternalStreamConnection.receiveMessage(InternalStreamConnection.java:224)
at com.mongodb.connection.UsageTrackingInternalConnection.receiveMessage(UsageTrackingInternalConnection.java:96)
at com.mongodb.connection.DefaultConnectionPool$PooledConnection.receiveMessage(DefaultConnectionPool.java:440)
at com.mongodb.connection.WriteCommandProtocol.receiveMessage(WriteCommandProtocol.java:262)
at com.mongodb.connection.WriteCommandProtocol.execute(WriteCommandProtocol.java:104)
at com.mongodb.connection.InsertCommandProtocol.execute(InsertCommandProtocol.java:67)
at com.mongodb.connection.InsertCommandProtocol.execute(InsertCommandProtocol.java:37)
at com.mongodb.connection.DefaultServer$DefaultServerProtocolExecutor.execute(DefaultServer.java:168)
at com.mongodb.connection.DefaultServerConnection.executeProtocol(DefaultServerConnection.java:289)
at com.mongodb.connection.DefaultServerConnection.insertCommand(DefaultServerConnection.java:118)
at com.mongodb.operation.MixedBulkWriteOperation$Run$2.executeWriteCommandProtocol(MixedBulkWriteOperation.java:465)
at com.mongodb.operation.MixedBulkWriteOperation$Run$RunExecutor.execute(MixedBulkWriteOperation.java:656)
at com.mongodb.operation.MixedBulkWriteOperation$Run.execute(MixedBulkWriteOperation.java:411)
at com.mongodb.operation.MixedBulkWriteOperation$1.call(MixedBulkWriteOperation.java:177)
at com.mongodb.operation.MixedBulkWriteOperation$1.call(MixedBulkWriteOperation.java:168)
at com.mongodb.operation.OperationHelper.withConnectionSource(OperationHelper.java:426)
at com.mongodb.operation.OperationHelper.withConnection(OperationHelper.java:417)
at com.mongodb.operation.MixedBulkWriteOperation.execute(MixedBulkWriteOperation.java:168)
at com.mongodb.operation.MixedBulkWriteOperation.execute(MixedBulkWriteOperation.java:74)
at com.mongodb.Mongo.execute(Mongo.java:845)
at com.mongodb.Mongo$2.execute(Mongo.java:828)
at com.mongodb.MongoCollectionImpl.executeSingleWriteRequest(MongoCollectionImpl.java:550)
at com.mongodb.MongoCollectionImpl.insertOne(MongoCollectionImpl.java:317)
at com.mongodb.MongoCollectionImpl.insertOne(MongoCollectionImpl.java:307)
at cn.xlink.cecep.server.mongo.MongoService.insertIngore(MongoService.java:49)
at cn.xlink.cecep.server.mongo.impl.ContrlCabinetServiceImpl.insert(ContrlCabinetServiceImpl.java:78)
at com.alibaba.dubbo.common.bytecode.Wrapper17.invokeMethod(Wrapper17.java)
at com.alibaba.dubbo.rpc.proxy.javassist.JavassistProxyFactory$1.doInvoke(JavassistProxyFactory.java:46)
at com.alibaba.dubbo.rpc.proxy.AbstractProxyInvoker.invoke(AbstractProxyInvoker.java:72)
at com.alibaba.dubbo.rpc.protocol.InvokerWrapper.invoke(InvokerWrapper.java:53)
at com.alibaba.dubbo.rpc.filter.ExceptionFilter.invoke(ExceptionFilter.java:64)
at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
at com.alibaba.dubbo.monitor.support.MonitorFilter.invoke(MonitorFilter.java:75)
at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
at com.alibaba.dubbo.rpc.filter.TimeoutFilter.invoke(TimeoutFilter.java:42)
at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
at com.alibaba.dubbo.rpc.protocol.dubbo.filter.TraceFilter.invoke(TraceFilter.java:78)
at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
at com.alibaba.dubbo.rpc.filter.ContextFilter.invoke(ContextFilter.java:60)
at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
at com.alibaba.dubbo.rpc.filter.GenericFilter.invoke(GenericFilter.java:112)
at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
at com.alibaba.dubbo.rpc.filter.ClassLoaderFilter.invoke(ClassLoaderFilter.java:38)
at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
at com.alibaba.dubbo.rpc.filter.EchoFilter.invoke(EchoFilter.java:38)
at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
at com.alibaba.dubbo.rpc.protocol.dubbo.DubboProtocol$1.reply(DubboProtocol.java:108)
at com.alibaba.dubbo.remoting.exchange.support.header.HeaderExchangeHandler.handleRequest(HeaderExchangeHandler.java:84)
at com.alibaba.dubbo.remoting.exchange.support.header.HeaderExchangeHandler.received(HeaderExchangeHandler.java:170)
at com.alibaba.dubbo.remoting.transport.DecodeHandler.received(DecodeHandler.java:52)
at com.alibaba.dubbo.remoting.transport.dispatcher.ChannelEventRunnable.run(ChannelEventRunnable.java:82)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)经过我的百度，以及查资料发现并不能解决我的问题，大部分说的是连接池满了什么的，重启或者修改配置之类的，但是我其他的查询，插入都是正常，只要执行这个接口，这个插入方法就报错，然后我就分析了代码，发现下面的可疑信息：
Decimal128 decimal128 = new Decimal128(new BigDecimal(data.getString("testNum")));
item_doc.put("testNum", decimal128);我这里用到了mongodb的新的类型Decimal128，是在3.4及以后的版本的新特性，实在3.4及以后的版本的新特性，官网地址：https://docs.mongodb.com/manual/reference/bson-types/
但是我自身的mongodb数据库版本是3.2.7，不支持这个新类型，导致错误。
总结来说就是你使用了Decimal128的Bson类型，但是你的mongodb版本低于3.4版本，不支持这个类型。
仅作参考，如果错漏欢迎留言指正。