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);
}
}