当我在表中插入值时使用DataSource类型连接时，我似乎并没有让PreparedStatement工作。 我尝试了类型转换：
PreparedStatement preparedStatement = (PreparedStatement) conn.prepareStatement("Some query");
但这似乎也不起作用并抛出空指针异常！
（P.S：我知道我可以达到同样的目标
Statement stmt = conn.createStatement（）; String sql =“INSERT INTO ... VALUES （.....）“; stmt.executeUpdate（sql）;
但我不想这样做！）
这是我的代码。 （所有.jar都已到位且引用的表和列名称有效且存在）：
import java.sql.*;
import javax.sql.DataSource;
import com.mysql.jdbc.PreparedStatement;
//...and all other necessary imports
public class CreateUserAccountDaoImpl implements CreateUserAccountDaoInterface {
@Override
public boolean validate(CreateUserAccountBean cuab) {
int resstat=0;
java.io.PrintWriter out = null;
Connection conn=null;
//CallableStatement cStmt=null;
try {
/* get the DataSource from using the JNDI name */
Class.forName("com.mysql.jdbc.Driver");
InitialContext ctx = new InitialContext();
DataSource ds = (DataSource)ctx.lookup("java:comp/env/jdbc/Test");
//username, pass,name, id,dob ,skillset, exp,designation ,email
//Create connection and then continue as usual other JDBC calls
conn=ds.getConnection();
//System.out.println("\nConnection Successful in " +lb.getBeanclassname()+ " !");
String sql = "INSERT INTO tbluser (username,pass,category,dname,id,dob,skillset,exp,designation,email)"
+ " VALUES (?, ?, ? ,?, ?, ? , ?, ?, ?, ?)";
//Create a PreparedStatment with that sql and insert the values with index:
/*1-username 2-pass 3-category 4-dname
5-id 6-dob 7-skillset 8-exp 9-designation 14-email*/
PreparedStatement preparedStatement = (PreparedStatement) conn.prepareStatement(sql);
preparedStatement.setString(1,cuab.getBeannuusrname());
preparedStatement.setString(2,cuab.getBeannupass());
preparedStatement.setString(3,cuab.getBeanusertype());
preparedStatement.setString(4,cuab.getBeannuname());
preparedStatement.setString(5,cuab.getBeannuempid());
preparedStatement.setString(6,cuab.getBeannudob());
preparedStatement.setString(7,cuab.getBeannuskill());
preparedStatement.setString(8,cuab.getBeannuexp());
preparedStatement.setString(9,cuab.getBeannudesg());
preparedStatement.setString(10,cuab.getBeannuemail());
preparedStatement.executeUpdate();
preparedStatement.clearParameters();
resstat=1;
System.out.println("Data inserted successfully!");
} catch (Exception e){
out.println("Failed!"+ e);
resstat=0;
}
if(resstat==1)
return true;
else
return false;
}
}