import  javax.swing.*; 
import  java.awt.*; 
import  java.awt.event.*; 
import  java.awt.event.ActionEvent; 

/**
 * Java中弹出对话框中的字体设置问题
 * @author 五斗米 <如转载请保留作者和出处>
 * @blog <a href="http://blog.csdn.net/mq612">http://blog.csdn.net/mq612
 */

public  class  Test  { 
   JFrame  frame; 
   JButton  button; 
   Font  font; 

   public  Test(){ 
       font  =  new  Font("宋体",0,12); 
       UIManager.put("Button.font",font); 
       UIManager.put("Label.font",font); 
       frame  =  new  JFrame("Test"); 
       button  =  new  JButton("弹出"); 
       button.addActionListener(new  ActionListener()  { 
           public  void  actionPerformed(ActionEvent  actionEvent)  { 
               JLabel  l  =  new  JLabel("用户名或密码错误\\n请重新输入"); 
               JOptionPane.showMessageDialog(frame,l,"错误",JOptionPane.ERROR_MESSAGE); 
           } 
       }); 
       frame.getContentPane().add(button); 
       frame.setSize(300,  200); 
       frame.setVisible(true); 
   } 
   public  static  void  main(String[]  args)  { 
       new  Test(); 
   } 
}

//源代码片段来自云代码http://yuncode.net