Write（）方法写入文件

public static void main(String[] args){    try{        BufferedWriter out = new BufferedWriter(new FileWriter("D:\\temp\\runoon.txt"));//创建文件        out.write("cainiaojiaocheng");//向文件中写入字符串        out.close();//关闭文件。运行之后查看目录下应该生成文件，并且文件中有写入的字符串        System.out.println("create file successfully");    }catch(IOException e){

    }

}

//用readLine()从文件中读取数据try{    BufferedReader in = new BufferedReader(new FileReader("D:\\temp\\runoon.txt"));//获取文件地址    String str;//创建一个字符串对象来缓存下读出来的字符串    while((str=in.readLine())!=null){        System.out.print(str);    }}catch(IOException e){    System.out.println(e);}

创建临时文件，向文件中对家数据

import java.io.*;

/** * Created by Sandy.Liu on 2017/8/8. */public class CreateTempFile {    public static void main(String[] args){        try {            File fileDir = new File("D://Temp//");            File tempFile = File.createTempFile("createTempFile", ".txt",fileDir);            tempFile.deleteOnExit();            BufferedWriter bw = new BufferedWriter(new FileWriter(tempFile));            bw.write("String 1");            bw.close();            System.out.println("temp file is created");

            //向文件中追加数据，这里注意不要创建一个新的BufferedWriter对象，要用之前的对象，不然会再创建一个新的tempfile，而不是之前的那个对象追加            bw = new BufferedWriter(new FileWriter(tempFile,true));            bw.write("string 2");            bw.close();            BufferedReader br = new BufferedReader(new FileReader(tempFile));            String str;            while((str=br.readLine())!=null){                System.out.println(str);            }            br.close();        }catch (IOException e){            System.out.println(e);        }    }}重命名

import java.io.*;

/** * Created by Sandy.Liu on 2017/8/8. */public class FileRename {    public static void main(String[] args){     File oldName = new File("D://Temp//TestSource.txt");     File newName = new File("D://Temp//TestSource1.txt");     if(oldName.renameTo(newName)){         System.out.println("rename successfully");     }else{         System.out.println("Error");     }    }}

复制文件，用到BufferedWriter，BufferedReader,InputStream，OutputStream

import java.io.*;

/** * Created by Sandy.Liu on 2017/8/8. */public class CopyFile {    public static void main(String[] args){        try {            //创建文件，并向文件中写入数据            BufferedWriter bf = new BufferedWriter(new FileWriter("D://Temp//TestSource.txt"));            bf.write("this is for test copy files from TestSource.txt to TestTarget.txt");            bf.close();

            //读出文件到buffer里，为写入另一个文件做准备            InputStream is = new FileInputStream(new File("D://Temp//TestSource.txt"));            byte[] buf = new byte[1024];

            //把buffer里的数据写入到目标文件中去            OutputStream ot = new FileOutputStream(new File("D://Temp//TestTarget.txt"));            int len;            while((len=is.read(buf))>0){                ot.write(buf,0,len);            }

            //从目标文件中读取字符串，输出到控制台            BufferedReader br = new BufferedReader(new FileReader("D://Temp//TestTarget.txt"));            String str;            while((str=br.readLine())!=null){                System.out.println(str);            }        }catch(IOException e){            System.out.println(e);        }    }}