我正在尝试对数据库执行多次调用，第一次调用（select）工作正常..但是当进入第二次调用时我得到此错误
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after statement closed.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
at com.mysql.jdbc.Util.getInstance(Util.java:381)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:984)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:956)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:926)
at com.mysql.jdbc.StatementImpl.checkClosed(StatementImpl.java:380)
at com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1250)
at MysqlConnect.main(MysqlConnect.java:77)
at __SHELL13.run(__SHELL13.java:6)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at bluej.runtime.ExecServer$3.run(ExecServer.java:724)
这是我的代码（请原谅仍在学习）
import java.sql.*;
public class MysqlConnect{
public static void main(String[] args) {
Connection conn = null;
String url = "jdbc:mysql://localhost:3306/";
String dbName = "MyBussiness";
String driver = "com.mysql.jdbc.Driver";
String userName = "mambo";
String password = "jambo";
try {
Class.forName(driver).newInstance();
conn = DriverManager.getConnection(url+dbName,userName,password);
System.out.println("Connected to the database");
/*SELECTING DATA */
// Get a statement from the connection
Statement stmt = conn.createStatement() ;
System.out.println("--------------------------------------------.");
System.out.println("Retrieving items from the customers table (USING SELECT)...");
System.out.println("--------------------------------------------.");
Thread.sleep(2000);
// Execute the query
ResultSet rs = stmt.executeQuery( "SELECT * FROM customers" ) ;
// Loop through the result set
while( rs.next() )
{
System.out.print( rs.getInt(1) ) ;
System.out.print(", ");
System.out.print( rs.getString(2) );
System.out.print(", ");
System.out.print( rs.getString(3) );
System.out.print(", ");
System.out.print( rs.getString(4) );
System.out.print(", ");
System.out.print( rs.getString(5) );
System.out.print(", ");
System.out.print( rs.getString(6) );
System.out.print(", ");
System.out.print( rs.getString(7) );
System.out.print(", ");
System.out.print( rs.getString(8) );
System.out.print(", ");
System.out.print( rs.getString(9) );
System.out.print(", ");
System.out.println( rs.getString(10) );
}
// Close the result set, statement and the connection
rs.close() ;
stmt.close() ;
/*UPDATING DATA */
// Get a statement from the connection
conn = DriverManager.getConnection(url+dbName,userName,password);
Statement stmt2 = conn.createStatement() ;
System.out.println("---------------------------------------------------------------------------.");
System.out.println("Updating Customers Table for Customer ID 1 Federico Gutierrez Address1 Field (USING UPDATE)...");
System.out.println("---------------------------------------------------------------------------.");
Thread.sleep(2000);
// Execute the query
ResultSet rs2 = stmt.executeQuery("UPDATE Customers SET Address1='999 Mambo Avenue' WHERE CustomerID = 1");
// Loop through the result set
while( rs2.next() )
{
System.out.print( rs2.getInt(1) ) ;
System.out.print(", ");
System.out.print( rs2.getString(2) );
System.out.print(", ");
System.out.print( rs2.getString(3) );
System.out.print(", ");
System.out.print( rs2.getString(4) );
System.out.print(", ");
System.out.print( rs2.getString(5) );
System.out.print(", ");
System.out.print( rs2.getString(6) );
System.out.print(", ");
System.out.print( rs2.getString(7) );
System.out.print(", ");
System.out.print( rs2.getString(8) );
System.out.print(", ");
System.out.print( rs2.getString(9) );
System.out.print(", ");
System.out.println(rs2.getString(10) );
}
// Close the result set, statement and the connection
rs2.close() ;
stmt2.close() ;
/*INSERTING DATA */
// Get a statement from the connection
conn = DriverManager.getConnection(url+dbName,userName,password);
Statement stmt3 = conn.createStatement() ;
System.out.println("---------------------------------------------------------------------------.");
System.out.println("Inserting a new customer (Mario Villalobos) into the customers table ... (USING INSERT)");
System.out.println("---------------------------------------------------------------------------.");
Thread.sleep(2000);
// Execute the query
ResultSet rs3 = stmt.executeQuery("INSERT INTO Customers (SSN, FirstName, LastName, Address1, Address2, State, City, Zip, PhoneNumber)"+
" VALUES ('444559999','Mario','Villalobos','777 Boynton Beach','Apt 4R','FL','Boynton Beach','33436','(555)444-5555'");
// Loop through the result set
while( rs3.next() )
{
System.out.print( rs3.getInt(1) ) ;
System.out.print(", ");
System.out.print( rs3.getString(2) );
System.out.print(", ");
System.out.print( rs3.getString(3) );
System.out.print(", ");
System.out.print( rs3.getString(4) );
System.out.print(", ");
System.out.print( rs3.getString(5) );
System.out.print(", ");
System.out.print( rs3.getString(6) );
System.out.print(", ");
System.out.print( rs3.getString(7) );
System.out.print(", ");
System.out.print( rs3.getString(8) );
System.out.print(", ");
System.out.print( rs3.getString(9) );
System.out.print(", ");
System.out.println(rs3.getString(10) );
}
// Close the result set, statement and the connection
rs3.close() ;
stmt3.close() ;
/*DELETING DATA */
// Get a statement from the connection
conn = DriverManager.getConnection(url+dbName,userName,password);
Statement stmt4 = conn.createStatement() ;
System.out.println("---------------------------------------------------------------------------.");
System.out.println("Deleting customer where the name is George... (USING Delete)");
System.out.println("---------------------------------------------------------------------------.");
Thread.sleep(2000);
// Execute the query
ResultSet rs4 = stmt.executeQuery("DELETE FROM Customers WHERE FirstName Like '%George%'");
// Loop through the result set
while( rs4.next() )
{
System.out.print( rs4.getInt(1) ) ;
System.out.print(", ");
System.out.print( rs4.getString(2) );
System.out.print(", ");
System.out.print( rs4.getString(3) );
System.out.print(", ");
System.out.print( rs4.getString(4) );
System.out.print(", ");
System.out.print( rs4.getString(5) );
System.out.print(", ");
System.out.print( rs4.getString(6) );
System.out.print(", ");
System.out.print( rs4.getString(7) );
System.out.print(", ");
System.out.print( rs4.getString(8) );
System.out.print(", ");
System.out.print( rs4.getString(9) );
System.out.print(", ");
System.out.println(rs4.getString(10) );
}
// Close the result set, statement and the connection
rs4.close() ;
stmt4.close() ;
//Reseting data
conn = DriverManager.getConnection(url+dbName,userName,password);
Statement stmt5 = conn.createStatement() ;
ResultSet rs5 = stmt.executeQuery("UPDATE Customers SET Address1='555 YY Ave' WHERE CustomerID = 1");
rs5.close() ;
stmt5.close() ;
conn = DriverManager.getConnection(url+dbName,userName,password);
Statement stmt6 = conn.createStatement() ;
ResultSet rs6 = stmt.executeQuery("DELETE FROM Customers WHERE FirstName Like '%Mario%'");
rs6.close() ;
stmt6.close() ;
conn = DriverManager.getConnection(url+dbName,userName,password);
Statement stmt7 = conn.createStatement() ;
ResultSet rs7 = stmt.executeQuery("INSERT INTO Customers (SSN, FirstName, LastName, Address1, Address2, State, City, Zip, PhoneNumber)"+
" VALUES ('923431432','George','Scott','2325 S Babcock St',' ','FL','Melbourne','32901','(321)984-4910'");
rs7.close() ;
stmt7.close() ;
conn.close() ;
System.out.println("Disconnected from database");
} catch (Exception e) {
e.printStackTrace();
}
}
}
非常感谢任何帮助。
注意：它告诉我第一次通过后连接已关闭，但我没有conn.Close（）;直到最后，你可以看到。
答案 0 :(得分：3)
ResultSet rs2 = stmt.executeQuery(...)
// ^^^^
你的意思是stmt2。请重新检查所有代码，以确保不会重复使用语句。
答案 1 :(得分：1)
如果您现在还没有发现它，您将重新使用已关闭的相同SQlStatement。这一行：
ResultSet rs2 = stmt.executeQuery("UPDATE Customers SET Address1='999 Mambo Avenue' WHERE CustomerID = 1");
应该是：
ResultSet rs2 = stmt2.executeQuery("UPDATE Customers SET Address1='999 Mambo Avenue' WHERE CustomerID = 1");
答案 2 :(得分：0)
进行了一些更正，但代码仍然不太好。应该管用。
import java.sql.*;
public class MysqlConnect{
public static void main(String[] args) {
Connection conn = null;
String url = "jdbc:mysql://localhost:3306/";
String dbName = "MyBussiness";
String driver = "com.mysql.jdbc.Driver";
String userName = "mambo";
String password = "jambo";
try {
Class.forName(driver).newInstance();
conn = DriverManager.getConnection(url+dbName,userName,password);
System.out.println("Connected to the database");
/*SELECTING DATA */
// Get a statement from the connection
Statement stmt = conn.createStatement() ;
System.out.println("--------------------------------------------.");
System.out.println("Retrieving items from the customers table (USING SELECT)...");
System.out.println("--------------------------------------------.");
Thread.sleep(2000);
// Execute the query
ResultSet rs = stmt.executeQuery( "SELECT * FROM customers" ) ;
// Loop through the result set
while( rs.next() )
{
System.out.print( rs.getInt(1) ) ;
System.out.print(", ");
System.out.print( rs.getString(2) );
System.out.print(", ");
System.out.print( rs.getString(3) );
System.out.print(", ");
System.out.print( rs.getString(4) );
System.out.print(", ");
System.out.print( rs.getString(5) );
System.out.print(", ");
System.out.print( rs.getString(6) );
System.out.print(", ");
System.out.print( rs.getString(7) );
System.out.print(", ");
System.out.print( rs.getString(8) );
System.out.print(", ");
System.out.print( rs.getString(9) );
System.out.print(", ");
System.out.println( rs.getString(10) );
}
// DO NOT Close the result set, statement and the connection
/*UPDATING DATA */
// Get a statement from the connection
System.out.println("---------------------------------------------------------------------------.");
System.out.println("Updating Customers Table for Customer ID 1 Federico Gutierrez Address1 Field (USING UPDATE)...");
System.out.println("---------------------------------------------------------------------------.");
Thread.sleep(2000);
// Execute the UPDATE
stmt.executeUpdate("UPDATE Customers SET Address1='999 Mambo Avenue' WHERE CustomerID = 1");
// Loop through the result set
//NO ResultSet for UPDATE
// DON'T Close the result set, statement and the connection
/*INSERTING DATA */
// Get a statement from the connection
System.out.println("---------------------------------------------------------------------------.");
System.out.println("Inserting a new customer (Mario Villalobos) into the customers table ... (USING INSERT)");
System.out.println("---------------------------------------------------------------------------.");
Thread.sleep(2000);
// Execute the UPDATE
stmt.executeUpdate("INSERT INTO Customers (SSN, FirstName, LastName, Address1, Address2, State, City, Zip, PhoneNumber)"+
" VALUES ('444559999','Mario','Villalobos','777 Boynton Beach','Apt 4R','FL','Boynton Beach','33436','(555)444-5555'");
// Loop through the result set INSERT HAS NO RESULTSET
// Close the result set, statement and the connection
/*DELETING DATA */
// Get a statement from the connection
System.out.println("---------------------------------------------------------------------------.");
System.out.println("Deleting customer where the name is George... (USING Delete)");
System.out.println("---------------------------------------------------------------------------.");
Thread.sleep(2000);
// Execute the query, NO UPDATE
stmt.executeUpdate("DELETE FROM Customers WHERE FirstName Like '%George%'");
// Loop through the result set
// Close the result set, statement and the connection
//Reseting data
stmt.executeUpdate("UPDATE Customers SET Address1='555 YY Ave' WHERE CustomerID = 1");
stmt.executeUpdate("DELETE FROM Customers WHERE FirstName Like '%Mario%'");
stmt.executeUpdate("INSERT INTO Customers (SSN, FirstName, LastName, Address1, Address2, State, City, Zip, PhoneNumber)"+
" VALUES ('923431432','George','Scott','2325 S Babcock St',' ','FL','Melbourne','32901','(321)984-4910'");
// NOW CLOSE DB RS, STATEMENT, CONN
rs.close() ;
stmt.close() ;
conn.close() ;
System.out.println("Disconnected from database");
} catch (Exception e) {
e.printStackTrace();
}
}
}