java 对文件的操作

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java 遍历文件夹文件：

package com.mixian.file;

import java.io.File;

public class getAllname {

	public static void main(String[] args) {
		File fileDir  = new File("c:/");
			File[] files = fileDir.listFiles();
			for(int i = 0; i 
 
 将字节流读入到数组中：
 
 
package com.mixian.file;

import java.io.IOException;
import java.io.InputStream;

public class inStreamTest {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		InputStream is = System.in;
		byte[] bt = new byte[1024];
		try {
			 is.read(bt);  //将字节流读入到数组中
			 System.out.println("xx"+new String(bt).trim());
				is.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
		
	}

}
 
 
 
 
 
输出是类似的：
 
 
OutputStream out = System.out;
		try {
			out.write("12".getBytes());
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
 
 
 读取文件信息：
 
 
try {
			FileInputStream is = new FileInputStream("c:/new.txt");
			int length;
			byte[] by = new byte[1024];
			try {
				while((length = is.read(by))!=-1){
					String str = new String(by,0,length);
					System.out.println(str);
				}
			} catch (IOException e) {
				e.printStackTrace();
			}
			
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		}
 
 
 文件写入：
 
 
File file = new File("c:/mixian.txt");
		if(!file.exists()){
			file.createNewFile();
		}
		
		FileOutputStream out = new FileOutputStream(file);
		byte[] byx = "test out".getBytes();
		out.write(byx);
		out.close();
 
 
 汉字的输入输出：
 
 
	//读取汉字的时候会出问题，因为一个汉字是占两个字节
		InputStreamReader isr = new InputStreamReader(System.in);
		char[] chars = new char[100];
		isr.read(chars);
		//int str = isr.read(chars);
		String str = new String(chars);
		System.out.println(str.trim());
 
 
 文件的读取：
 
 
//文件读取
		FileReader reader = new FileReader("c:/mixian.txt");
		int length;
		while((length = reader.read())!=-1){
			System.out.println((char)length);
		}