Java Swing 绝对布局管理方法，null布局（转）

import java.awt.Container;

import java.awt.Dimension;

import java.awt.Rectangle;

import java.awt.Toolkit;

import javax.swing.JButton;

import javax.swing.JCheckBox;

import javax.swing.JComboBox;

import javax.swing.JFrame;

import javax.swing.JPasswordField;

import javax.swing.JTextField;

public class Log extends JFrame {

    public static void main(String[] args) {

        Log log = new Log();

    }

    private JButton btLog;

    private JTextField tfUser;

    private JPasswordField tfPwd;

    private JCheckBox pwdKeep;

    private JComboBox adminType;

    public Log() {

        super("固定资产管理系统");

        super.setSize(380, 292);

        super.setVisible(true);

        super.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        centered(this);

        btLog = new JButton("登     录");

        btLog.setBounds(new Rectangle(93, 220, 180, 30));//参数分别是坐标x，y，宽，高

        this.setLayout(null);//设置布局管理器为空

        this.add(btLog);

        tfUser = new JTextField();

        tfUser.setBounds(new Rectangle(73, 115, 220, 25));

        this.add(tfUser);

        tfPwd = new JPasswordField();

        tfPwd.setBounds(new Rectangle(73, 150, 220, 25));

        this.add(tfPwd);

        pwdKeep = new JCheckBox("记住密码");

        pwdKeep.setBounds(new Rectangle(68, 185, 110, 25));

        this.add(pwdKeep);

        adminType = new JComboBox(new String[] { "普通职员", "管理员", "高级管理员" });

        adminType.setBounds(new Rectangle(183, 185, 100, 25));

        this.add(adminType);

    }

//布局居中方法

    public void centered(Container container) {

        Toolkit toolkit = Toolkit.getDefaultToolkit();

        Dimension screenSize = toolkit.getScreenSize();

        int w = container.getWidth();

        int h = container.getHeight();

        container.setBounds((screenSize.width - w) / 2,

                (screenSize.height - h) / 2, w, h);

    }

}