java程序报了几个错，大伙来看看

下面是我写的一段程序，打算用java连接openoffice来将word文档改换成pdf格式，不知道怎么解决这些错
java.net.ConnectException: connection failed: socket,host=localhost,port=8100,tcpNoDelay=1: java.net.ConnectException: Connection refused: connect
at com.artofsolving.jodconverter.openoffice.connection.AbstractOpenOfficeConnection.connect(AbstractOpenOfficeConnection.java:79)
at com.chinacreator.test.JOD4DocToPDF.docToPdf(JOD4DocToPDF.java:21)
at com.chinacreator.test.JOD4DocToPDF$TestThread.run(JOD4DocToPDF.java:49)
java.net.ConnectException: connection failed: socket,host=localhost,port=8100,tcpNoDelay=1: java.net.ConnectException: Connection refused: connect
at com.artofsolving.jodconverter.openoffice.connection.AbstractOpenOfficeConnection.connect(AbstractOpenOfficeConnection.java:79)
at com.chinacreator.test.JOD4DocToPDF.docToPdf(JOD4DocToPDF.java:21)
at com.chinacreator.test.JOD4DocToPDF$TestThread.run(JOD4DocToPDF.java:49)
java.net.ConnectException: connection failed: socket,host=localhost,port=8100,tcpNoDelay=1: java.net.ConnectException: Connection refused: connect
at com.artofsolving.jodconverter.openoffice.connection.AbstractOpenOfficeConnection.connect(AbstractOpenOfficeConnection.java:79)
at com.chinacreator.test.JOD4DocToPDF.docToPdf(JOD4DocToPDF.java:21)
at com.chinacreator.test.JOD4DocToPDF$TestThread.run(JOD4DocToPDF.java:49)
Exception in thread "Thread-1" java.lang.NullPointerException
at com.artofsolving.jodconverter.openoffice.connection.AbstractOpenOfficeConnection.disconnect(AbstractOpenOfficeConnection.java:88)
at com.chinacreator.test.JOD4DocToPDF.docToPdf(JOD4DocToPDF.java:31)
at com.chinacreator.test.JOD4DocToPDF$TestThread.run(JOD4DocToPDF.java:49)
Exception in thread "Thread-0" java.lang.NullPointerException
at com.artofsolving.jodconverter.openoffice.connection.AbstractOpenOfficeConnection.disconnect(AbstractOpenOfficeConnection.java:88)
at com.chinacreator.test.JOD4DocToPDF.docToPdf(JOD4DocToPDF.java:31)
at com.chinacreator.test.JOD4DocToPDF$TestThread.run(JOD4DocToPDF.java:49)
Exception in thread "Thread-2" java.lang.NullPointerException
at com.artofsolving.jodconverter.openoffice.connection.AbstractOpenOfficeConnection.disconnect(AbstractOpenOfficeConnection.java:88)
at com.chinacreator.test.JOD4DocToPDF.docToPdf(JOD4DocToPDF.java:31)
at com.chinacreator.test.JOD4DocToPDF$TestThread.run(JOD4DocToPDF.java:49)