Java调用 hadoop client 创建文件报错

Question

org.apache.hadoop.ipc.RemoteException(java.io.IOException): 

File /hdfsapi/test/c.txt could only be replicated to 0 nodes instead of minReplication (=1).  

There are 1 datanode(s) running and 1 node(s) are excluded in this operation.  at 

org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.chooseTarget4NewBlock(BlockManager.java:1595)

at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:3287)

at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.addBlock(NameNodeRpcServer.java:677)

...

datanode 正常启动  防火墙关闭了  调用创建文件夹的API是成功的

在命令行使用hadoop fs  所有操作也正常

在浏览器看到文件大小为0  求解释？？？