Java常用工具类2 - 崔笑颜的博客

/**
 * List去重
 */
private List<String> removeDuplicate(List<String> list) {
    LinkedHashSet<String> set = new LinkedHashSet<String>(list.size());
    set.addAll(list);
    list.clear();
    list.addAll(set);
    return list;
}

List<String> list= list.stream().distinct().collect(Collectors.toList());

// 注意Comparator.comparing要根据参数的类型进行选择
private List<GroupVO> removeDuplicateGroupVO(List<GroupVO> groupVOS){
    return groupVOS.stream().collect(
            Collectors.collectingAndThen(
                    Collectors.toCollection(
                            () -> new TreeSet<>(Comparator.comparing(GroupVO::getId))
                    ), ArrayList::new
            )
    );
}

// 注意Comparator.comparing要根据参数的类型进行选择
private List<GroupVO> removeDuplicateGroupVO(List<GroupVO> groupVOS){
    return groupVOS.stream().collect(
            Collectors.collectingAndThen(
                    Collectors.toCollection(
                            () -> new TreeSet<>(Comparator.comparing(GroupVO::getId))
                    ), ArrayList::new
            )
    );
}

public static <T> Predicate<T> distinctByKey(Function<? super T, Object> keyExtractor) {
      Map<Object, Boolean> map = new ConcurrentHashMap<>();
      return t -> map.putIfAbsent(keyExtractor.apply(t), Boolean.TRUE) == null;
  }
 
// remove duplicate
persons.stream().filter(distinctByKey(p -> p.getId())).forEach(p -> System.out.println(p));

package eg2;
 
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.util.Scanner;
 
/******************
 * 文件的复制
 *******************/
 
public class Test2_3 {
 
    public static void main(String[] args) throws IOException {
        // TODO Auto-generated method stub
        @SuppressWarnings("resource")
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入指定文件夹路径：");
        String oldpath = sc.next();
        System.out.println("请输入目标文件夹路径：");
        String newpath = sc.next();
        System.out.println("请输入要复制的文件名：");
        String filename = sc.next();
        copy(filename, oldpath, newpath);
        System.out.println("复制完成！");
    }
 
    private static void copy(String filename, String oldpath, String newpath) throws IOException {
        // TODO Auto-generated method stub
        File oldpaths = new File(oldpath + "/" + filename);
        File newpaths = new File(newpath + "/" + filename);
        if (!newpaths.exists()) {
            Files.copy(oldpaths.toPath(), newpaths.toPath());
        } else {
            newpaths.delete();
            Files.copy(oldpaths.toPath(), newpaths.toPath());
        }
 
        // String newfile = "";
        // newfile += newpaths;
        // FileInputStream in = new FileInputStream(oldpaths);
        // File file = new File(newfile);
        // if (!file.exists()) {
        // file.createNewFile();
        // }
        // FileOutputStream out = new FileOutputStream(newpaths);
        // byte[] buffer = new byte[1024];
        // int c;
        // while ((c = in.read(buffer)) != -1) {
        // for (int i = 0; i < c; i++) {
        // out.write(buffer[i]);
        // }
        // }
        // in.close();
        // out.close();
    }
 
}

package util;
 
/**
 * @program: transformation
 * @description:
 * @author: cuixy
 * @create: 2019-07-26 14:30
 **/
 
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;
 
/**
 * 压缩算法类
 * 实现文件压缩，文件夹压缩，以及文件和文件夹的混合压缩
 * @author ljheee
 *
 */
public class CompactAlgorithm {
 
    /**
     * 完成的结果文件--输出的压缩文件
     */
    File targetFile;
 
    public CompactAlgorithm() {}
 
    public CompactAlgorithm(File target) {
        targetFile = target;
        if (targetFile.exists())
            targetFile.delete();
    }
 
    /**
     * 压缩文件
     *
     * @param srcfile
     */
    public void zipFiles(File srcfile) {
 
        ZipOutputStream out = null;
        try {
            out = new ZipOutputStream(new FileOutputStream(targetFile));
 
            if(srcfile.isFile()){
                zipFile(srcfile, out, "");
            } else{
                File[] list = srcfile.listFiles();
                for (int i = 0; i < list.length; i++) {
                    compress(list[i], out, "");
                }
            }
 
            System.out.println("压缩完毕");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (out != null)
                    out.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
 
    /**
     * 压缩文件夹里的文件
     * 起初不知道是文件还是文件夹--- 统一调用该方法
     * @param file
     * @param out
     * @param basedir
     */
    private void compress(File file, ZipOutputStream out, String basedir) {
        /* 判断是目录还是文件 */
        if (file.isDirectory()) {
            this.zipDirectory(file, out, basedir);
        } else {
            this.zipFile(file, out, basedir);
        }
    }
 
    /**
     * 压缩单个文件
     *
     * @param srcfile
     */
    public void zipFile(File srcfile, ZipOutputStream out, String basedir) {
        if (!srcfile.exists())
            return;
 
        byte[] buf = new byte[1024];
        FileInputStream in = null;
 
        try {
            int len;
            in = new FileInputStream(srcfile);
            out.putNextEntry(new ZipEntry(basedir + srcfile.getName()));
 
            while ((len = in.read(buf)) > 0) {
                out.write(buf, 0, len);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (out != null)
                    out.closeEntry();
                if (in != null)
                    in.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
 
    /**
     * 压缩文件夹
     * @param dir
     * @param out
     * @param basedir
     */
    public void zipDirectory(File dir, ZipOutputStream out, String basedir) {
        if (!dir.exists())
            return;
 
        File[] files = dir.listFiles();
        for (int i = 0; i < files.length; i++) {
            /* 递归 */
            compress(files[i], out, basedir + dir.getName() + "/");
        }
    }
 
 
 
}
 

//压缩测试
File f = new File("/Users/cuixiaoyan/Downloads/浏览器下载");
new CompactAlgorithm(new File( "/Users/cuixiaoyan/Downloads/",f.getName()+".zip")).zipFiles(f);