我建议您让您的jpanel面板使用gridlayout，而不是null布局，并且不要设置imageview大小，而是确保类具有 getPreferredSize() 方法重写，返回适当大小的维度。如果你打电话来 pack() 在jframe上添加组件之后，布局管理器将为您调整大小。

考虑一下这个计划：

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.awt.*;
import java.awt.event.*;
import javax.imageio.ImageIO;
import javax.swing.*;

public class Init extends JFrame{
    JPanel view = new JPanel();
    JMenuBar mBar = new JMenuBar();
    JMenu menu = new JMenu("File");
    JMenuItem mItemOpen = new JMenuItem("Open");
    JMenuItem mItemExit = new JMenuItem("Exit");
    JFileChooser fc = new JFileChooser();
    JTextField txtPath = new JTextField();

    BufferedImage myPicture;
    File filePath;
    String path;

    public Init(){
        mBar.add(menu);
        menu.add(mItemOpen);
        menu.addSeparator();
        menu.add(mItemExit);
        setJMenuBar(mBar);
        txtPath.setEditable(false);
        mItemOpen.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){
                fc.showOpenDialog(null);
                filePath = fc.getSelectedFile();
                path = filePath.getPath();
                txtPath.setText(path);
                try {
                    //view.removeAll();
                    myPicture = ImageIO.read(new File(path));
                    JLabel picLabel = new JLabel(new ImageIcon(myPicture));
                    view.add(picLabel);
                    revalidate();

                } catch (IOException ex) {
                    ex.printStackTrace();
                }
            }
        });
        setLayout(new BorderLayout());
        getContentPane().add(new JScrollPane(view),BorderLayout.CENTER);
        getContentPane().add(txtPath,BorderLayout.SOUTH);
        setTitle(".:My Picture Viewer:.");
        setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        //pack();
        setSize(1024,768);
        setVisible(true);
    }

    public static void main(String [] args){
        SwingUtilities.invokeLater(new Runnable(){
            public void run(){
                new Init();
            }
        });         
    }
}