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IO流下分为字节流与字符流，每个流又分为输入输出以及读写。
字节流的两个基类为InputStream与OutputStream。
字符流为Reader和Writer
一般的缓冲流读写字符：
BufferedReader br = new BufferedReader(new FileReader("b.txt"));
如果有编码格式的话使用：
BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream("d:\\test\\xiong.txt"), "gbk"));
读取一个文本里面的内容那个，并随机输出一行内容。
public static void main(String[] args) throws IOException { BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream("d:\\test\\xiong.txt"), "gbk")); ArrayList<String> list = new ArrayList<String>(); String line = null; while ((line=br.readLine())!=null){ list.add(line); } int random = new Random().nextInt(list.size()); System.out.println(list.get(random)); }
复制文件夹下的文件，文件里有相片，视频所以使用字节流：
package cn; import java.io.*; public class FileDemo2 { public static void main(String[] args) throws IOException { File srcFolder = new File("d:\\demo"); File destFolder = new File("d:\\test"); if (!destFolder.exists()){ destFolder.mkdir(); } File[] files = srcFolder.listFiles(); for (File file:files){ File newFile = new File(destFolder, file.getName()); copy(file, newFile); } } private static void copy(File file, File newFile) throws IOException{ BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file)); BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(newFile)); int len = 0; byte[] bys = new byte[1024]; while ((len=bis.read(bys))!=-1){ bos.write(bys, 0 , len); }
bis.close()
bos.close()
} }
将一个文件夹下的以.java结尾的文本文件复制到另一个文件夹并改为以.jad结尾
package cn; import java.io.*; import java.util.ArrayList; import java.util.Random; /** * Created by Administrator on 2015/3/11. */ public class FileDemo { public static void main(String[] args) throws IOException { File srcFolder = new File("c:\\java"); File destFolder = new File("c:\\jad"); if(!(destFolder.exists())){ destFolder.mkdir(); } File[] fileArray = srcFolder.listFiles(new FilenameFilter() { @Override public boolean accept(File dir, String name) { return new File(dir, name).isFile()&&name.endsWith(".java"); } }); for(File file:fileArray){ String name = file.getName(); File newFile = new File(destFolder, name); copy(file, newFile); } File[] destFileArray = destFolder.listFiles(); for (File destFile:destFileArray){ System.out.println(destFile); String name = destFile.getName(); String newName = name.replace(".java", ".jad"); File newFile = new File(destFolder, newName); destFile.renameTo(newFile); } } private static void copy(File file, File newFile) throws IOException{ BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file)); BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(newFile)); int len = 0; byte[] bys = new byte[1024]; while ((len=bis.read(bys))!=-1){ bos.write(bys, 0 , len); } bis.close(); bos.close(); } }
复制一个文件夹下的所有内容到指定目录
package cn; import java.io.*; import java.util.ArrayList; import java.util.Random; /** * Created by Administrator on 2015/3/11. */ public class FileDemo { public static void main(String[] args) throws IOException { File srcFile = new File("d:\\demos"); File destFile = new File("c:\\"); copyFolder(srcFile, destFile); } private static void copyFolder(File srcFile, File destFile) throws IOException{ if(srcFile.isDirectory()){ File newFolder = new File(destFile, srcFile.getName()); newFolder.mkdir(); File[] fileArray = srcFile.listFiles(); for (File file:fileArray){ copyFolder(file, newFolder); } }else{ File newFile = new File(destFile, srcFile.getName()); copyFile(srcFile, newFile); } } private static void copyFile(File srcFile, File newFile) throws IOException{ BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(newFile)); BufferedInputStream bis = new BufferedInputStream(new FileInputStream(srcFile)); int len = 0; byte[] bys = new byte[1024]; while ((len=bis.read(bys))!=-1){ bos.write(bys, 0, len); } bis.close(); bos.close(); } }
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原文地址：http://www.cnblogs.com/tuifeideyouran/p/4332528.html
