Java各种文件的读写和文件夹遍历方法

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.util.HashMap;

public class TxtFileRead {
	public static void main(String[] args) {
		readFile1();
		System.out.println("===================");
		//readFile2(); //JDK 7及以上才可以使用
	}

	public static void readFile1() {
		FileInputStream fis = null;
		InputStreamReader isr = null;
		BufferedReader br = null;
		try {
			fis = new FileInputStream("c:/temp/abc.txt"); // 节点类
			isr = new InputStreamReader(fis, "UTF-8"); // 转化类
			//isr = new InputStreamReader(fis);
			br = new BufferedReader(isr); // 装饰类
			// br = new BufferedReader(new InputStreamReader(new
			// FileInputStream("c:/temp/abc.txt")))
			String line;
			while ((line = br.readLine()) != null) // 每次读取一行
			{
				System.out.println(line);
			}
		} catch (Exception ex) {
			ex.printStackTrace();
		} finally {
			try {
				br.close(); // 关闭最后一个类，会将所有的底层流都关闭
			} catch (Exception ex) {
				ex.printStackTrace();
			}
		}
	}

	public static void readFile2() {
		String line;
		//try-resource 语句，自动关闭资源
		try (BufferedReader in = new BufferedReader(new InputStreamReader(new FileInputStream("c:/temp/abc.txt")))) {
			while ((line = in.readLine()) != null) {
				System.out.println(line);
			}
		}
		catch(Exception ex)
		{
			ex.printStackTrace();
		}
	}
}

import java.io.*;

public class TxtFileWrite {
	public static void main(String[] args) {
		writeFile1();
		System.out.println("===================");
		//writeFile2(); // JDK 7及以上才可以使用
	}

	public static void writeFile1() {
		FileOutputStream fos = null;
		OutputStreamWriter osw = null;
		BufferedWriter bw = null;
		try {
			fos = new FileOutputStream("c:/temp/abc.txt"); // 节点类
			osw = new OutputStreamWriter(fos, "UTF-8"); // 转化类
			//osw = new OutputStreamWriter(fos); // 转化类
			bw = new BufferedWriter(osw); // 装饰类
			// br = new BufferedWriter(new OutputStreamWriter(new
			// FileOutputStream("c:/temp/abc.txt")))
			bw.write("我们是");
			bw.newLine();
			bw.write("Ecnuers.^^");
			bw.newLine();
		} catch (Exception ex) {
			ex.printStackTrace();
		} finally {
			try {
				bw.close(); // 关闭最后一个类，会将所有的底层流都关闭
			} catch (Exception ex) {
				ex.printStackTrace();
			}
		}
	}

	public static void writeFile2() {
		//try-resource 语句，自动关闭资源
		try (BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("c:/temp/abc.txt")))) {
			bw.write("我们是");
			bw.newLine();
			bw.write("Ecnuers.^^");
			bw.newLine();
		} catch (Exception ex) {
			ex.printStackTrace();
		}
	}
}

import java.io.*;
public class BinFileRead{
  public static void main(String[] args) throws Exception{
	  readFile();
  }
  public static void readFile() {
		//try-resource 语句，自动关闭资源
		try (DataInputStream dis = new DataInputStream(new BufferedInputStream(new FileInputStream("c:/temp/def.dat")))) {
			String a, b;
		    int c, d;
		    a=dis.readUTF();
		    c=dis.readInt();
		    d=dis.readInt();
		    b=dis.readUTF();
		    System.out.println("a: "+a);
		    System.out.println("c: "+c);
		    System.out.println("d: "+d);
		    System.out.println("b: "+b);
		}
		catch(Exception ex)
		{
			ex.printStackTrace();
		}
	}
}

import java.io.*;
public class BinFileWrite{
  public static void main(String[] args) throws Exception{
	writeFile();
    System.out.println("done.");
  }
  
  public static void writeFile() {
	  FileOutputStream fos = null;
	  DataOutputStream dos = null;
	  BufferedOutputStream bos = null;
		try {
			fos = new FileOutputStream("c:/temp/def.dat"); // 节点类
			bos = new BufferedOutputStream(fos); // 装饰类
			dos = new DataOutputStream(bos); // 装饰类		
			
			dos.writeUTF("a");
			dos.writeInt(20);
			dos.writeInt(180);
			dos.writeUTF("b");
		} catch (Exception ex) {
			ex.printStackTrace();
		} finally {
			try {
				dos.close(); // 关闭最后一个类，会将所有的底层流都关闭
			} catch (Exception ex) {
				ex.printStackTrace();
			}
		}
	}
}

import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.FileVisitOption;
import java.nio.file.FileVisitResult;
import java.nio.file.FileVisitor;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.PathMatcher;
import java.nio.file.Paths;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.EnumSet;

class Search implements FileVisitor {

	private final PathMatcher matcher;

	public Search(String ext) {
		matcher = FileSystems.getDefault().getPathMatcher("glob:" + ext);
	}

	public void judgeFile(Path file) throws IOException {
		Path name = file.getFileName();
		if (name != null && matcher.matches(name)) {
			//文件名字已经匹配
			System.out.println("Searched file was found: " + name + " in " + file.toRealPath().toString());
		}
	}

	@Override
	public FileVisitResult postVisitDirectory(Object dir, IOException exc) throws IOException {
		System.out.println("Visited: " + (Path) dir);
		return FileVisitResult.CONTINUE;
	}

	@Override
	public FileVisitResult preVisitDirectory(Object dir, BasicFileAttributes attrs) throws IOException {
		return FileVisitResult.CONTINUE;
	}

	@Override
	public FileVisitResult visitFile(Object file, BasicFileAttributes attrs) throws IOException {
		judgeFile((Path) file);
		return FileVisitResult.CONTINUE;
	}

	@Override
	public FileVisitResult visitFileFailed(Object file, IOException exc) throws IOException {
		// report an error if necessary
		return FileVisitResult.CONTINUE;
	}
}
//查找某一个目录下所有的jpg文件，包括子文件夹
public class SearchJPGFiles {

	public static void main(String[] args) throws IOException {
		//定义扩展名，和待查找目录
		String ext = "*.jpg";
		Path fileTree = Paths.get("C:/temp/");
		Search walk = new Search(ext);
		EnumSet<FileVisitOption> opts = EnumSet.of(FileVisitOption.FOLLOW_LINKS);

		Files.walkFileTree(fileTree, opts, Integer.MAX_VALUE, walk);

	}
}

## 文件属性遍历文件夹

import java.io.*;
public class FileAttributeTest{
  public static void main(String[] args){
	//创建目录
	File d=new File("c:/temp");
	if(!d.exists())
	{
		d.mkdirs();  //mkdir 创建单级目录  mkdirs 连续创建多级目录
	}
	System.out.println("Is d directory? " + d.isDirectory());
	
	//创建文件  
    File f=new File("C:/temp/abc.txt");    
    if(!f.exists())
    {    	
      try
      {
        f.createNewFile(); //创建abc.txt
      }
      catch(IOException e){ //可能会因为权限不足或磁盘已满报错
    	  e.printStackTrace();
      }
    }  
    
    //输出文件相关属性
    System.out.println("Is f file? " + f.isFile());
    System.out.println("Name: "+f.getName());
    System.out.println("Parent: "+f.getParent());
    System.out.println("Path: "+f.getPath());
    System.out.println("Size: "+f.length()+" bytes");
    System.out.println("Last modified time: "+f.lastModified()+"ms");
    
    //遍历d目录下所有的文件信息
    System.out.println("list files in d directory");
    File[] fs = d.listFiles();  //列出d目录下所有的子文件，不包括子目录下的文件
    for(File f1:fs)
    {
    	System.out.println(f1.getPath());
    }
    
    //f.delete(); //删除此文件
    //d.delete(); //删除目录
  }
}

import java.io.File;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

public class PathTest {
	public static void main(String[] args) {
		// Path 和 java.io.File 基本类似
		// 获得path方法一,c:/temp/abc.txt
		Path path = FileSystems.getDefault().getPath("c:/temp", "abc.txt");
		System.out.println(path.getNameCount());

		// 获得path方法二，用File的toPath()方法获得Path对象
		File file = new File("c:/temp/abc.txt");
		Path pathOther = file.toPath();
		// 0,说明这两个path是相等的
		System.out.println(path.compareTo(pathOther));

		// 获得path方法三
		Path path3 = Paths.get("c:/temp", "abc.txt");
		System.out.println(path3.toString());

		// 合并两个path
		Path path4 = Paths.get("c:/temp");
		System.out.println("path4: " + path4.resolve("abc.txt"));

		if (Files.isReadable(path)) {
			System.out.println("it is readable");
		} else {
			System.out.println("it is not readable");
		}
	}
}

import java.io.IOException;
import java.nio.file.DirectoryStream; // nio是jdk7中扩充的io类
import java.nio.file.Files;
import java.nio.file.LinkOption;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.Date;

public class FilesTest {
	
	public static void main(String[] a)
	{
		moveFile();
		fileAttributes();
		createDirectory();
	}

	public static void moveFile() {
		Path from = Paths.get("c:/temp", "abc.txt");
		//移动c:/temp/abc.txt到c:/temp/test/def.txt，如目标文件已存在，就替换
		Path to = from.getParent().resolve("test/def.txt");
		try {
			//文件的大小bytes
			System.out.println(Files.size(from));
			//调用文件移动方法  如果目标文件已经存在，就替换
			Files.move(from, to, StandardCopyOption.REPLACE_EXISTING);
		} catch (IOException e) {
			System.err.println("移动文件错误" + e.getMessage());
		}
	}
	
	
	public static void fileAttributes(){
		Path path = Paths.get("c:/temp");
		//1
		System.out.println(Files.isDirectory(path, LinkOption.NOFOLLOW_LINKS));
		//2
		try {
			//获得文件的基础属性
			BasicFileAttributes attributes = Files.readAttributes(path, BasicFileAttributes.class);
			System.out.println(attributes.isDirectory());
			System.out.println(new Date(attributes.lastModifiedTime().toMillis()).toLocaleString());
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	
	public static void createDirectory(){
		Path path = Paths.get("c:/temp/test");
		try {
			//创建文件夹
			if(Files.notExists(path)){
				Files.createDirectories(path);
				System.out.println("create dir");
			}else{
				System.out.println("dir exists");
			}
			Path path2 = path.resolve("A.java"); 
			Path path3 = path.resolve("B.java");
			Path path4 = path.resolve("C.txt");
			Path path5 = path.resolve("D.jpg");
			Files.createFile(path2);
			Files.createFile(path3);
			Files.createFile(path4);
			Files.createFile(path5);
			
			//不加条件遍历
			DirectoryStream<Path> paths = Files.newDirectoryStream(path);
			for(Path p : paths){
				System.out.println(p.getFileName());
			}
			System.out.println();
			
			//创建一个带有过滤器,过滤文件名以java txt结尾的文件
			DirectoryStream<Path> pathsFilter = Files.newDirectoryStream(path, "*.{java,txt}");
			for(Path p : pathsFilter){
				System.out.println(p.getFileName());
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}