我用servlet验证用户登陆...............................
String connuser = "root";
String connpassword = "password";
String driver = "com.mysql.jdbc.Driver";
String url = "mysql:jdbc://localhost:3306/admin";
Connection conn = null;
String sql = "select * from login where adminname=?,adminpassword=?";
String username = request.getParameter("username");
String password = request.getParameter("password");
try {
Class.forName(driver);
conn = DriverManager.getConnection(url, connuser, connpassword);
PreparedStatement ps = conn.prepareStatement(sql);
ps.setString(1, username);
ps.setString(2, password);
ResultSet rs = ps.executeQuery(sql);
if(rs==null||rs.next()==null){ //The operator == is undefined for the
return; // argument type(s) boolean null
} //这应该没有问题吧,返回都是boolean......
//不知道为什么呀??
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}......................................
String connuser = "root";
String connpassword = "password";
String driver = "com.mysql.jdbc.Driver";
String url = "mysql:jdbc://localhost:3306/admin";
Connection conn = null;
String sql = "select * from login where adminname=?,adminpassword=?";
String username = request.getParameter("username");
String password = request.getParameter("password");
try {
Class.forName(driver);
conn = DriverManager.getConnection(url, connuser, connpassword);
PreparedStatement ps = conn.prepareStatement(sql);
ps.setString(1, username);
ps.setString(2, password);
ResultSet rs = ps.executeQuery(sql);
if(rs==null||rs.next()==null){ //The operator == is undefined for the
return; // argument type(s) boolean null
} //这应该没有问题吧,返回都是boolean......
//不知道为什么呀??
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}......................................
解决方案 »
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if(rs==null||rs.next()==null){ //The operator == is undefined for the
return; // argument type(s) boolean null
} //改成这样
if(rs.next()){
return true;
}else{
return false;
}
//或者这样
if (rs != null && rs.next()) {
return true;
}else{
return false;
}