Java Swing 绝对布局管理方法，null布局

首先把相关容器的布局方式设为 setLayout(null);

然后调用组件的  setBounds() 方法

设置button的位置为(100,100) 长宽分别为 60，25

jButton.setBounds(new Rectangle(100, 100, 60, 25));

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);
    }
}