用Bean访问数据库时出错
public boolean executeUpdate(String yourId,String bookId){
boolean update = false;
int rowCount1 = 0;
int rowCount2 = 0;
int rowCount3 = 0;
String sql1 = "UPDATE book_info SET is_lend='n' WHERE book_number=" +
bookId;
System.out.println(sql1);
String sql2 = "UPDATE readerinfo SET presentbook+=1 WHERE card_id=" +
yourId;
System.out.println(sql2);
String sql3 =
"INSERT INTO book_lend_info (card_id,book_number,lend_time) values (" +
yourId + "," + bookId + "," + "GETDATE())";
System.out.println(sql3);
try {
if (conn == null)
//如果没连接,先连接数据库
getJDBCConnection();
System.out.println("start1");
if (conn != null) { //有连接,则执行sql更新语句
stmt = conn.createStatement();
System.out.println("start2");
rowCount1 = stmt.executeUpdate(sql1);
rowCount2 = stmt.executeUpdate(sql2);
rowCount3 = stmt.executeUpdate(sql3);
System.out.println("start3");
if ( (rowCount1 != 0) && (rowCount2 != 0) && (rowCount3 != 0))
update = true;
}
控制台显示如下:
UPDATE book_info SET is_lend='n' WHERE book_number=0000000002
UPDATE readerinfo SET presentbook+=1 WHERE card_id=0000000001
INSERT INTO book_lend_info (card_id,book_number,lend_time) values (0000000001,00
00000002,GETDATE())
start1
start2
<2004-4-5 下午09时45分19秒> <Error> <HTTP> <101017> <[ServletContext(id=2766683,
name=DefaultWebApp,context-path=)] Root cause of ServletException
java.lang.NullPointerException
at Library.JDBCBean.executeUpdate(JDBCBean.java:250)
at jsp_servlet.__add._jspService(__add.java:158)
at weblogic.servlet.jsp.JspBase.service(JspBase.java:27)
at weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run
(ServletStubImpl.java:1058)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubIm
pl.java:401)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubIm
pl.java:445)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubIm
pl.java:306)
at weblogic.servlet.internal.WebAppServletContext$ServletInvocationActio
n.run(WebAppServletContext.java:5445)
at weblogic.security.service.SecurityServiceManager.runAs(SecurityServic
eManager.java:780)
at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppSe
rvletContext.java:3105)
at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestIm
pl.java:2588)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:213)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:189)
>
网页显示如下:
Error 500--Internal Server Error
From RFC 2068 Hypertext Transfer Protocol -- HTTP/1.1:
10.5.1 500 Internal Server Error
The server encountered an unexpected condition which prevented it from fulfilling the request.
请指教