Guava---文件操作Files

文章目录

guava复制文件

java NIO复制文件

移动文件

读取文件内容(一行一行读)

读取文件内容(按条件读取)

计算文件hashcode (可对比两个文件是否一样)

写文件

获取某路径目录

获取某路径目录(自定义过滤)

guava复制文件

private static String from = "D:\自定义代码\Guava\guava\src\1.txt";
private static String to = "D:\自定义代码\Guava\guava\src\2.txt";

Files.copy(new File(from),new File(to));

java NIO复制文件

java.nio.file.Files.copy(Paths.get(from),
                Paths.get(to), StandardCopyOption.REPLACE_EXISTING);

移动文件

//to若存在,将被删除,重新生成
Files.move(new File(from),new File(to));

读取文件内容(一行一行读)

List<String> strings = Files.readLines(new File(to), Charsets.UTF_8);

读取文件内容(按条件读取)

private static void guavaReadFilesProcess() throws IOException {
        LineProcessor<List<String>> lineProcessor = new LineProcessor<List<String>>() {
            List<String> list = new ArrayList<>();
            @Override
            public boolean processLine(String s) throws IOException {
                System.out.println("读到内容：" + s);
                list.add("前缀-" + s);
                return true;   //return false,不再读取下面内容
            }

            @Override
            public List<String> getResult() {
                System.out.println("返回结果： "+ list);
                return list;
            }
        };
        List<String> strings = Files.asCharSource(new File(to), Charsets.UTF_8).readLines(lineProcessor);
        System.out.println(strings);
    }
          /**
         *  读到内容：java
         *  读到内容：C++
         *  读到内容：PHP
         *  返回结果： [前缀-java, 前缀-C++, 前缀-PHP]
         *  [前缀-java, 前缀-C++, 前缀-PHP]
         */

计算文件hashcode (可对比两个文件是否一样)

//Hashing.md5();Hashing.sha256()
HashCode hash = Files.asByteSource(new File(to)).hash(Hashing.sha512());

写文件

         String path = "D:\自定义代码\Guava\guava\src\2.txt";
        File file = new File(path);
        Files.asCharSink(file, Charsets.UTF_8).write("hhhh");
        String read = Files.asCharSource(file, Charsets.UTF_8).read();
        System.out.println("读取: "+ read);

        //追加内容
        Files.asCharSink(file, Charsets.UTF_8, FileWriteMode.APPEND).write("
hhhh2");
        String read2 = Files.asCharSource(file, Charsets.UTF_8).read();
        System.out.println("读取: "+ read2);

获取某路径目录

public static void main(String[] args) {
        String path = "D:\自定义代码\Guava\guava\src\main";
        File file = new File(path);
        //获取path下子目录
        Iterable<File> childrens = Files.fileTreeTraverser().children(file);
        for (File children : childrens) {
            System.out.println("子目录: " + children);

        }
        //获取path下所有目录  preOrderTraversal postOrderTraversal顺序不一样
        FluentIterable<File> files = Files.fileTreeTraverser().preOrderTraversal(file);
        for (File file1 : files) {
            System.out.println("全目录: " + file1);
        }
        /**
         子目录: D:自定义代码Guavaguavasrcmainjava
        */

获取某路径目录(自定义过滤)

public static void main(String[] args) {
        String path = "D:\自定义代码\Guava\guava\src\main";
        File file = new File(path);                //preOrderTraversal postOrderTraversal顺序不一样
        FluentIterable<File> files = Files.fileTreeTraverser().preOrderTraversal(file).filter(new Predicate<File>() {
            @Override
            public boolean apply(@Nullable File input) {
                return input.isFile();  //只要文件
            }
        });
        for (File file1 : files) {
            System.out.println(file1);
        }
    }