Question

jdbc连接数据库的问题

*以下是代码：
package com.jdbcTest.t09;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class MainTest {

public static void main(String[] args) {

try {
//1注册驱动
DriverManager.registerDriver(new com.mysql.jdbc.Driver());

//2.建立连接
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/student","root","123456");

//3.创建statement,跟数据库打交道一定需要这个对象
Statement st = conn.createStatement();

// 4.执行查询
String sql ="select * from t_stu";
ResultSet rs = st.executeQuery(sql);

//5遍历查询每一条记录
while(rs.next()){
int id = rs.getInt("id");
String name = rs.getString("name");
int age = rs.getInt("age");

System.out.println("id"+id+"---name="+name+"---age="+age);

rs.close();
st.close();
conn.close();

}

} catch (SQLException e) {

e.printStackTrace();
}
}

}

//以下是运行错误信息：
Tue Sep 04 18:02:18 CST 2018 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.
id1---name=zhangsan---age=18
java.sql.SQLException: Operation not allowed after ResultSet closed
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:965)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:898)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:887)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:861)
at com.mysql.jdbc.ResultSetImpl.checkClosed(ResultSetImpl.java:743)
at com.mysql.jdbc.ResultSetImpl.next(ResultSetImpl.java:6289)
at com.jdbcDemo.t09.MainTest.main(MainTest.java:32)

看得我眼花，求解

Answer 1

兄弟，你的这段
rs.close();
st.close();
conn.close();
关闭资源得放循环外面 嘛，不然都关闭连接了还怎么读取。