import javax.swing.*;
import java.awt.*;
public class GridBagLayoutDemo extends JFrame {
  private GridBagLayout gbLayout = new GridBagLayout();
  private  GridBagConstraints constraints=new GridBagConstraints( );
  private JLabel lbUser,lbPassword;
  private JTextField  tfUser,tfPassword;
  private JButton btnLog;
  private Container container;
  public GridBagLayoutDemo()  {
    super("網格包布局");
    this.setSize(300,200);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE );
  }
  private void setConstraints(GridBagConstraints gbc,int row,int column,
                       int numRows,int numColumns,int Weightx,int Weighty){
    gbc.gridx=row;
    gbc.gridy=column;
    gbc.gridwidth=numRows;
    gbc.gridheight=numColumns;
    gbc.weightx=Weightx;
    gbc.weighty=Weighty;
  }
  public void setLayout(){
   container=this.getContentPane();
   container.setLayout(gbLayout);
   //添加用戶名標簽
   constraints.fill=GridBagConstraints.NONE;
   constraints.anchor=GridBagConstraints.CENTER;
   setConstraints(constraints,0,0,1,1,0,0);
   lbUser=new JLabel("用戶名");
   gbLayout.setConstraints(lbUser,constraints);
   container.add(lbUser);
   //添加用戶名文本框
   constraints.fill=GridBagConstraints.HORIZONTAL;
   setConstraints(constraints,1,0,1,1,100,100);
   tfUser=new JTextField();
   gbLayout.setConstraints(tfUser,constraints);
   container.add(tfUser);
   //添加密碼標簽
   constraints.fill=GridBagConstraints.NONE;
   setConstraints(constraints,0,1,1,1,0,0);
   lbPassword=new JLabel("密碼");
   gbLayout.setConstraints(lbPassword,constraints);
   container.add(lbPassword);
   //添加密文本框
   constraints.fill=GridBagConstraints.HORIZONTAL;
   setConstraints(constraints,1,1,1,1,100,100);
   tfPassword=new JTextField();
   gbLayout.setConstraints(tfPassword,constraints);
   container.add(tfPassword);
   //添加登錄按鈕
   constraints.fill=GridBagConstraints.CENTER;
   setConstraints(constraints,0,2,2,1,0,0);
   btnLog=new JButton("登錄");
   gbLayout.setConstraints(btnLog,constraints);
   container.add(btnLog);
  }
  public static void main(String[] args) {
    GridBagLayoutDemo frame = new GridBagLayoutDemo();
    frame.setLayout();
    frame.show();
  }
}