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我试图使用sql查询导出数据从数据库中的数据,但获取空指针异常。没有线索去除它。我在Bold字体的行中得到这个异常。获取空指针异常将数据从数据库导出到xml
try {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.newDocument();
Element results = doc.createElement("Results");
doc.appendChild(results);
Class.forName("oracle.jdbc.OracleDriver");
Connection con = DriverManager
.getConnection("jdbc:oracle:thin:@localhost:1521:XE", "hr", "hr");
ResultSet rs = con.createStatement().executeQuery("select * from departments");
ResultSetMetaData rsmd = rs.getMetaData();
int colCount = rsmd.getColumnCount();
while (rs.next()) {
Element row = doc.createElement("Row");
results.appendChild(row);
for (int i = 1; i <= colCount; i++) {
String columnName = rsmd.getColumnName(i);
Object value = rs.getObject(i);
Element node = doc.createElement(columnName);
row.appendChild(node);
**node.appendChild(doc.createTextNode(value.toString()));**
}
}
DOMSource domSource = new DOMSource(doc);
TransformerFactory tf = TransformerFactory.newInstance();
Transformer transformer = tf.newTransformer();
transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
transformer.setOutputProperty(OutputKeys.METHOD, "xml");
transformer.setOutputProperty(OutputKeys.ENCODING, "ISO-8859-1");
StringWriter sw = new StringWriter();
StreamResult sr = new StreamResult(sw);
transformer.transform(domSource, sr);
System.out.println(sw.toString());
con.close();
rs.close();
} catch (Exception e) {
e.printStackTrace();
}
堆栈跟踪:
java.lang.NullPointerException
at org.ProjectXML.ui.DataBaseToXML.main(DataBaseToXML.java:61)
任何想法?
你能提供的堆栈跟踪? – CodeChimp
你在哪一行得到错误? –
@CodeChimp这里是堆栈跟踪:显示java.lang.NullPointerException \t在org.ProjectXML.ui.DataBaseToXML.main(DataBaseToXML.java:60)在该行 – Ritesh