Glassfish 从数据库中读取表
我在Java代码下运行时遇到了一个问题。我找不到Glassfish 从数据库中读取表,glassfish,java-ee-7,Glassfish,Java Ee 7,我在Java代码下运行时遇到了一个问题。我找不到DB.java类 ResultSet rs=DB.getConnection().createStatement().executeQuery(“从产品中选择*); while(rs.next()){ 系统输出打印(rs.getString(“pid”); System.out.print(rs.getString(“name”); 系统输出打印(rs.getString(“价格”)); 系统输出打印(rs.getString(“ava_数量”);
DB.java
类
ResultSet rs=DB.getConnection().createStatement().executeQuery(“从产品中选择*);
while(rs.next()){
系统输出打印(rs.getString(“pid”);
System.out.print(rs.getString(“name”);
系统输出打印(rs.getString(“价格”));
系统输出打印(rs.getString(“ava_数量”);
}
我正在使用Glassfish服务器。有人能帮我编写DB.java
类吗?getConnection()方法是类的一部分。正确初始化drivermanager,如本文所述:
供将来参考的示例代码:
import java.sql.*;
public class jdbcConn {
public static void main(String[] args) {
try {
Class.forName("org.apache.derby.jdbc.ClientDriver");
} catch(ClassNotFoundException e) {
System.out.println("Class not found "+ e);
}
System.out.println("JDBC Class found");
int no_of_rows = 0;
try {
Connection con = DriverManager.getConnection (
"jdbc:derby://localhost:1527/testDb","username", "password");
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery ("SELECT * FROM employee");
while (rs.next()) {
no_of_rows++;
}
System.out.println("There are "+ no_of_rows + " record in the table");
} catch(SQLException e){
System.out.println("SQL exception occured" + e);
}
}
}
您最好发布一条错误消息。请添加DB.java文件的用途。您想实现连接池吗?或者只是创建并返回新连接?发布答案取决于您的期望。