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1£©Êý¾Ý¿â²Ù×÷Àà,×ö¼òµ¥·â×° DB.java
package Test;
import java.sql.*;
public class DB {
 
 // ¼ÓÔØÇý¶¯
    static {
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            System.out.println("Çý¶¯¼ÓÔØ³ö´í");
        }
    }
 // »ñÈ¡Êý¾Ý¿âÁ¬½Ó
 public static Connection getConn() {
  Connection conn = null;
  try {
   conn = DriverManager.getConnection("jdbc:mysql://localhost/userinfo?user=root&password=abcd");
  } catch (SQLException e) {
   e.printStackTrace();
  }
  return conn;
 }
 // ¹Ø±ÕÊý¾Ý¿âÁ¬½Ó
 public static void closeConn(Connection conn) {
  try {
   if(conn != null) {
    conn.close();
    conn = null;
   }
  } catch (SQLException e) {
   e.printStackTrace();
  }
 }
 // ¹Ø±ÕStatement
 public static void closeStmt(Statement stmt) {
  try {
   if(stmt != null) {
    stmt.close();
    stmt = null;
   }
  } catch (SQLException e) {
   e.printStackTrace();
  }
 }
 // ¹Ø±ÕResultSet 
 public static void closeRs(ResultSet rs) {
  try {
   if(rs != null) {
    rs.close();
    rs = null;
   }
  } catch (SQLException e) {
   e.printStackTrace();
  }
 }
}
****************************


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   private int x,y;
   public test(int x,int y) {
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