Java Swing 多线程加载图片（保证顺序一致）

大二的时候做的课程设计，图片管理器，当时遇到图片很多的文件夹，加载顺序非常慢。虽然尝试用多个Thread加载图片，却无法保证图片按顺序加载。直到今天学会了使用Callable接口和Future接口，于是心血来潮实现了这个功能。

废话不多说，看代码。

多线程加载图片（核心）：

package com.lin.imagemgr;

import java.awt.Dimension;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FilenameFilter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.stream.Collectors;
import javax.swing.ImageIcon;
import javax.swing.JLabel;

import net.coobird.thumbnailator.Thumbnails;

public class ImageMgr {
private static ImageMgr instance = new ImageMgr();
private ImageMgr() {}
public static ImageMgr getInstance() {
 return instance;
}

//线程池
private ExecutorService executor = Executors.newFixedThreadPool(8);

public List<JLabel> loadImages(String path) {
 List<JLabel> images = new ArrayList<>();
 File file = new File(path);
 if (!file.isDirectory()) {
  throw new RuntimeException("need directory!");
 }
 File[] files = file.listFiles(new FilenameFilter() {

@Override
  public boolean accept(File dir, String name) {
   //thumbnail只支持jpg??
   if (name.endsWith(".jpg")) {
    return true;
   }
   return false;
  }
 });

//并发加载图片，并使用Future保存加载结果
 List<Future<MyLabel>> futures = new ArrayList<>();
 for (final File f : files) {
  Future<MyLabel> future = executor.submit(() -> {
   return new MyLabel(f.getName(), f.getAbsolutePath());
  });
  futures.add(future);
 }

//等待所有并发加载返回结果
 try {
  for (Future<MyLabel> future : futures) {
   MyLabel icon = future.get();
   images.add(icon);
  }
 } catch (InterruptedException e) {
  e.printStackTrace();
 } catch (ExecutionException e) {
  e.printStackTrace();
 }

//Java8使用stream API 进行排序
 List<JLabel> sortedList = images.stream().sorted().collect(Collectors.toList());

return sortedList;
}

//继承JLabel并实现Comparable接口，从而对JLabel进行排序
private static class MyLabel extends JLabel implements Comparable<MyLabel>{
 private static final long serialVersionUID = 1L;
 private String fileName;

public MyLabel(String fileName, String fullPath) {
  this.fileName = fileName;
  //使用thumbnailator生成缩略图
  try {
   BufferedImage bufferedImage = Thumbnails.of(fullPath)
   .size(100, 120)
   .asBufferedImage();
   setIcon(new ImageIcon(bufferedImage));
   setPreferredSize(new Dimension(100, 120));
  } catch (IOException e) {
   e.printStackTrace();
  }
 }

@Override
 public int compareTo(MyLabel o) {
  int result = this.fileName.compareTo(o.fileName);
  return result;
 }

}

}

Swing界面：

package com.lin.imagemgr;

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;

public class MainFrame extends JFrame{
private static final long serialVersionUID = 1L;
private JTextField pathField;
private JButton showBtn;
private JPanel contentPanel;

public void init() {
 JPanel topPanel = new JPanel(new FlowLayout(FlowLayout.LEFT, 5, 0));
 topPanel.setPreferredSize(new Dimension(800, 40));
 pathField = new JTextField(50);
 showBtn = new JButton("显示图片");
 topPanel.add(pathField);
 topPanel.add(showBtn);
 getContentPane().add(BorderLayout.NORTH, topPanel);
 contentPanel = new JPanel();
 contentPanel.setLayout(new FlowLayout(FlowLayout.LEFT, 5, 5));
 contentPanel.setPreferredSize(new Dimension(750, 1800));
 JScrollPane jsp = new JScrollPane(contentPanel);
 getContentPane().add(BorderLayout.CENTER, jsp);

showBtn.addActionListener((e) -> {
  try {
   loadImages();
  } catch (Exception ex) {
   ex.printStackTrace();
  }
 });

setSize(800, 650);
 setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 setLocationRelativeTo(null);
 setVisible(true);
}

public void loadImages() {
 contentPanel.removeAll();
 String path = pathField.getText();
 long start = System.currentTimeMillis();
 List<JLabel> images = ImageMgr.getInstance().loadImages(path);
 for (JLabel label :images) {
  contentPanel.add(label);
 }
 contentPanel.updateUI();
 long end = System.currentTimeMillis();
 System.out.println("加载需要" + (end - start) + "毫秒！");

}

public static void main(String[] args) {
 new MainFrame().init();
}

}

运行结果

在我的电脑上，加载92张图片并渲染到界面上，总共花了1568毫秒。大家可以找一个图片很多的文件夹，尝试加载大量图片的情况。

来源：http://blog.csdn.net/qq_21508059/article/details/78743696