public String User;
Model.JDBC j=new JDBC();
/**
* Creates new form Home_Page
*/
public Home_Page(String eid)
{
initComponents();
User=eid;
Toolkit t = Toolkit.getDefaultToolkit();
Dimension d = t.getScreenSize();
int w = (int) d.getWidth();
int h = (int) d.getHeight()-40;
setBounds(0, 0, w, h);
jLabel2.setText(new Controler.getDate().date());
time();
jLabel3.setText(eid);
ResultSet rs;
try
{
rs = j.getData("select eid from user where eid='"+eid+"'");
System.out.println(rs.next()+ " rs.next");
if(rs.next() != true)
{
System.out.println("rs.next");
//until this point it works but gives an exception
if(rs.getString(3).equals("Admin"))
{
System.out.println("if admin");
home.setEnabled(true);
job.setEnabled(true);
employee.setEnabled(true);
user.setEnabled(true);
machine.setEnabled(true);
branch.setEnabled(true);
}
else if(rs.getString(3).equals("user"))
{
System.out.println("else if");
home.setEnabled(true);
job.setEnabled(false);
employee.setEnabled(false);
user.setEnabled(false);
machine.setEnabled(true);
branch.setEnabled(false);
System.out.println("user can't see");
}
else
{
System.out.println("else");
}
}
else
{
System.out.println("outer else executed");
}
}
catch (Exception ex)
{
Logger.getLogger(Home_Page.class.getName()).log(Level.SEVERE, null, ex);
}
}
通过这个我试图过滤能够为普通用户点击我的Home_Page中出现的jbuttons，同时允许管理员查看并点击它们。 但是在第一次之后如果它不能正常工作。
异常这样说..
true rs.next
rs.next
Model.JDBC@15bc725
working
Mar 15, 2017 3:20:39 PM Viewer.Home_Page <init>
SEVERE: null
java.sql.SQLException: After end of result set
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1074)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:988)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:974)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:919)
at com.mysql.jdbc.ResultSetImpl.checkRowPos(ResultSetImpl.java:855)
at com.mysql.jdbc.ResultSetImpl.getStringInternal(ResultSetImpl.java:5773)
at com.mysql.jdbc.ResultSetImpl.getString(ResultSetImpl.java:5693)
at Viewer.Home_Page.<init>(Home_Page.java:65)
at Viewer.login.loginActionPerformed(login.java:119)
at Viewer.login.access$000(login.java:18)
at Viewer.login$1.actionPerformed(login.java:70)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6533)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6298)
at java.awt.Container.processEvent(Container.java:2236)
at java.awt.Component.dispatchEventImpl(Component.java:4889)
at java.awt.Container.dispatchEventImpl(Container.java:2294)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
at java.awt.Container.dispatchEventImpl(Container.java:2280)
at java.awt.Window.dispatchEventImpl(Window.java:2746)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:90)
at java.awt.EventQueue$4.run(EventQueue.java:731)
at java.awt.EventQueue$4.run(EventQueue.java:729)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
MySQL表名是user，第三列的列名是ulevel，到目前为止在varchar类型下输入的两个值是“user”和“Admin”。能不能请你帮我解决这个问题，让ifs工作，让那些jbuttons无法点击。
答案 0 :(得分：2)
你打两次rs.next()。
如果您在结果集中只有一条记录，则会导致错误。第二个问题是您访问第三列rs.getString(3)而您只选择一条。
答案 1 :(得分：2)
您的查询返回eid所以只返回一个值，但是rs.getString（3）：
rs = j.getData("select eid from user where eid='"+eid+"'");
//----------------------^^---------------------------------
if(rs.getString(3).equals("Admin"))
//--------------^-----------------
相反，你必须使用：
if(rs.getString(1).equals("Admin"))
//--------------^-----------------
Isuggest使用PreparedStatement而不是这会导致语法错误或SQL Injection
而不是：
rs = j.getData("select eid from user where eid='"+eid+"'");
你必须使用
rs = j.executeQuery("select eid from user where eid = ?");
rs.setString(1, eid);
注意
就像@Jens在他的回答中所说的那样，如果你使用两个rs.next()但是不能避免hasnext这会在ResultSet中不存在，你将会收到错误，所以为了避免这种情况，你必须重新 - 检查后执行result，如下所示：
System.out.println("----------->" + (result.next()));
result = preparedStatement.executeQuery();
答案 2 :(得分：1)
您只需通过rs.next（）方法迭代ResultSet，然后通过任何ResultSet getter获取列值。 例如，
Statement s = conn.createStatement ();
s.executeQuery ("SELECT id, name FROM user");
ResultSet rs = s.getResultSet();
rs = statement.executeQuery();
while (rs.next()) {
int id = resultSet.getInt("id");
int name = resultSet.getInt("name");
// ...
}