mysql> show variables like 'character%'; 
+--------------------------+--------------------------+ 
| Variable_name      | Value          | 
+--------------------------+--------------------------+ 
| character_set_client   | latin1          | 
| character_set_connection | latin1          | 
| character_set_database  | latin1          | 
| character_set_filesystem | binary          | 
| character_set_results  | latin1          | 
| character_set_server   | latin1          | 
| character_set_system   | utf8           | 
| character_sets_dir    | D:\MySQL\share\charsets\ | 
+--------------------------+--------------------------+ 

mysql> use test; 
mysql> create table messages ( 
  -> id int(4) unsigned auto_increment primary key, 
  -> message varchar(50) not null
  -> ) engine=myisam default charset=utf8; 
mysql> insert into messages (message) values ("测试MySQL中文显示"); 
mysql> select * from messages; 
+----+-------------------+ 
| id | message      | 
+----+-------------------+ 
| 1 | 测试MySQL中文显示 | 
+----+-------------------+

import java.sql.Connection; 
import java.sql.DriverManager; 
import java.sql.ResultSet; 
import java.sql.Statement; 
 
public class JDBCTest { 
  public static void main(String[] args) { 
    String driver = "com.mysql.jdbc.Driver"; 
    String url = "jdbc:mysql://localhost:3306/test"; 
    String user = "root"; 
    String password = "root"; 
 
    try { 
      Class.forName(driver); 
      Connection conn = DriverManager.getConnection(url, user, password); 
      Statement stmt = conn.createStatement(); 
      stmt.executeUpdate("insert into messages (message) values ('测试MySQL编码')"); 
      ResultSet rs = stmt.executeQuery("select * from messages"); 
      while (rs.next()) { 
        int id = rs.getInt("id"); 
        String message = rs.getString("message"); 
        System.out.println(id + " " + message); 
      } 
 
      rs.close(); 
      stmt.close(); 
      conn.close(); 
    } catch (Exception e) { 
      e.printStackTrace(); 
    } 
  } 
} 

mysql> show variables like 'character%'; 
+--------------------------+--------------------------+ 
| Variable_name      | Value          | 
+--------------------------+--------------------------+ 
| character_set_client   | utf8           | 
| character_set_connection | utf8           | 
| character_set_database  | utf8           | 
| character_set_filesystem | binary          | 
| character_set_results  | utf8           | 
| character_set_server   | utf8           | 
| character_set_system   | utf8           | 
| character_sets_dir    | D:\MySQL\share\charsets\ | 
+--------------------------+--------------------------+ 
mysql> use test; 
mysql> select * from messages; 
+----+-------------------------------+ 
| id | message            | 
+----+-------------------------------+ 
| 1 | 虏芒脢脭MySQL脰脨脦脛脧脭脢戮       | 
| 2 | ??MySQL??           | 
+----+-------------------------------+ 

mysql> select * from messages; 
+----+-------------------------------+ 
| id | message            | 
+----+-------------------------------+ 
| 1 | 虏芒脢脭MySQL脰脨脦脛脧脭脢戮       | 
| 2 | ??MySQL??           | 
| 3 | 娴嬭瘯MySQL缂栫爜         | 
+----+-------------------------------+ 

mysql> show variables like 'character%'; 
+--------------------------+--------------------------+ 
| Variable_name      | Value          | 
+--------------------------+--------------------------+ 
| character_set_client   | gb2312          | 
| character_set_connection | gb2312          | 
| character_set_database  | utf8           | 
| character_set_filesystem | binary          | 
| character_set_results  | gb2312          | 
| character_set_server   | utf8           | 
| character_set_system   | utf8           | 
| character_sets_dir    | D:\MySQL\share\charsets\ | 
+--------------------------+--------------------------+ 
mysql> use test; 
mysql> select * from messages; 
+----+-------------------+ 
| id | message      | 
+----+-------------------+ 
| 1 | ????MySQL???????? | 
| 2 | ??MySQL??     | 
| 3 | 测试MySQL编码   | 
+----+-------------------+