如何在控制台实现一个进度条

一、前言

在今天使用Java代码做一个集合的任务的时候，没在for循环中手动打印日志信息，导致在任务执行后根本不知道执行到了哪一步。

这点让我挺困扰的，于是在github上寻找有没有什么进度条的显示方式，我还真找到了。

看了一下代码，挺简单的，就将思路直接copy过来，实现了一个自己的控制台进度条。

vdurmont/etaprinter: Java console progress bar (github.com)

二、代码

抽象类ProcessBarUtil.java，里面有着基本的信息

package com.banmoon.utils.processbar;

import java.util.Iterator;
import java.util.function.Consumer;

/**
 * @author banmoon
 * @date 2024/03/08 15:52:13
 */
public abstract class ProcessBarUtil<T> implements Iterable<T> {

    /**
     * 遍历的数据
     */
    private final Iterable<T> data;

    /**
     * 结束数量
     */
    private final Integer startNum;

    /**
     * 当前的进度
     */
    private Integer current;

    /**
     * 结束数量
     */
    private final Integer endNum;

    /**
     * 进度条当前位置
     */
    private Integer processCurrentNum = 0;

    /**
     * 进度条总数
     */
    private final Integer processTotalNum = 100;

    public ProcessBarUtil(Iterable<T> data, Integer startNum, Integer current, Integer endNum) {
        this.data = data;
        this.startNum = startNum;
        this.current = current;
        this.endNum = endNum;
    }

    /**
     * 添加进度
     *
     * @param num 本次进度数量
     */
    public void add(Integer num) {
        this.current += num;
        this.processCurrentNum = (int) (100.0 * current / endNum);
        updateProcessBar(processCurrentNum, processTotalNum);
    }

    /**
     * 更新进度条
     *
     * @param current 当前进度
     */
    public void update(Integer current) {
        this.current = current;
        this.processCurrentNum = (int) (100.0 * current / endNum);
        updateProcessBar(processCurrentNum, processTotalNum);
    }

    protected abstract void updateProcessBar(Integer processCurrentNum, Integer processTotalNum);

    @Override
    public Iterator<T> iterator() {
        return data.iterator();
    }

    @Override
    public void forEach(Consumer<? super T> action) {
        data.forEach(t -> {
            action.accept(t);
            add(1);
        });
    }
}

以及它的第一个实现类ConsoleProcessBarUtil.java，使用控制台输出进度条

package com.banmoon.utils.processbar;

import cn.hutool.core.collection.IterUtil;

import java.io.IOException;
import java.io.OutputStream;
import java.util.stream.IntStream;
import java.util.stream.Stream;

/**
 * 控制台打印输出进度条
 *
 * @author banmoon
 * @date 2024/03/08 16:05:26
 */
public class ConsoleProcessBarUtil<T> extends ProcessBarUtil<T> {

    private final OutputStream outputStream;

    /**
     * 未完成的
     */
    private static final char incomplete = '░';

    /**
     * 完成的
     */
    private static final char complete = '█';


    private ConsoleProcessBarUtil(Iterable<T> data, Integer startNum, Integer current, Integer endNum) {
        super(data, startNum, current, endNum);
        outputStream = System.out;
    }

    public static <T> ProcessBarUtil<T> init(Iterable<T> data) {
        return new ConsoleProcessBarUtil<>(data, 0, 0, IterUtil.size(data));
    }

    public static ProcessBarUtil<?> init(Integer startNum, Integer endNum) {
        return new ConsoleProcessBarUtil<>(null, startNum, startNum, endNum);
    }

    @Override
    protected void updateProcessBar(Integer processCurrentNum, Integer processTotalNum) {
        String processBar = generateProcessBar(processCurrentNum, processTotalNum);
        try {
            outputStream.write("\r".getBytes());
            outputStream.write(processBar.getBytes());
        } catch (IOException e) {
            throw new RuntimeException("an error occurred while printing the progress bar");
        }
    }

    private String generateProcessBar(Integer processCurrentNum, Integer processTotalNum) {
        StringBuilder sb = new StringBuilder("[");
        Stream.generate(() -> complete)
                .limit(processCurrentNum)
                .forEach(sb::append);
        IntStream.range(processCurrentNum, processTotalNum)
                .mapToObj(i -> incomplete)
                .forEach(sb::append);
        sb.append("] ");
        if (processCurrentNum >= processTotalNum) {
            sb.append("complete\n");
        } else {
            sb.append(processCurrentNum).append("%");
        }
        return sb.toString();
    }

}

三、测试效果

package com.banmoon.utils.stream;

import cn.hutool.core.util.RandomUtil;
import com.banmoon.utils.processbar.ConsoleProcessBarUtil;
import com.banmoon.utils.processbar.ProcessBarUtil;
import org.junit.Assert;
import org.junit.Test;

import java.util.List;
import java.util.concurrent.TimeUnit;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

public class ProcessBarUtilTest {

    @Test
    public void iterableTest() {
        List<Integer> list = IntStream.range(0, 100).boxed().collect(Collectors.toList());
        ConsoleProcessBarUtil
                .init(list)
                .forEach(str -> {
                    try {
                        // 模拟业务执行
                        TimeUnit.MILLISECONDS.sleep(RandomUtil.randomInt(50, 200));
                    } catch (InterruptedException e) {
                        throw new RuntimeException(e);
                    }
                });
        Assert.assertEquals(list.size(), 100);
    }

    @Test
    public void forTest() {
        int current = 50;
        int total = 200;
        ProcessBarUtil<?> processBarUtil = ConsoleProcessBarUtil.init(current, total);
        while (current < total) {
            try {
                // 模拟业务执行
                TimeUnit.MILLISECONDS.sleep(RandomUtil.randomInt(50, 200));
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
            current++;
            processBarUtil.update(current);
        }
        Assert.assertEquals(current, total);
    }


}