I/O模式

文件:存储数据的一种方式;

File类

读文件

//读文件        try {            FileInputStream fileInputStream=                    new FileInputStream("f:/Io/test.txt");            byte[] data = new byte[1024];            try {                int len;                while((len=fileInputStream.read(data))!=-1){                    String string = new String(data,0,len);                    System.out.println(string);                }                fileInputStream.close();            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        } catch (FileNotFoundException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }

写文件

try {            FileOutputStream fos =                     new FileOutputStream("f:/Io/abc.txt");            try {                fos.write("abc".getBytes());                fos.flush();                fos.close();            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        } catch (FileNotFoundException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }

判断文件是否存在

if(!file3.exists()){            System.out.println("bucunzai");

创建文件

File file = new File("f:"+File.separator                            +"io"+File.separator+"old");//找到所指文件夹        if(!file.exists()){            file.mkdir();//如果该文件夹不存在则创建一个文件夹        }        if (file.exists()) {            File file2 = new File(file.getAbsolutePath()                                    +File.separator+"old.txt");//如果存在所述文件夹,判断所述文件是否存在            if(!file2.exists()){ // 如果文件不存在                try {                    FileOutputStream fileOutputStream=new FileOutputStream(file2);//创建新的输出文件;                    try {                        fileOutputStream.write("hello file".getBytes());                        fileOutputStream.flush();                        fileOutputStream.close();//关闭输出流;                    }

删除文件

if(file.exists()){        file.delete();        }        if (!file.exists()) {            System.out.println("no.....");        }

BufferReader

try {            FileReader fReader =                     new FileReader("f:/Io/test.txt");            //流链               BufferedReader bReader = new BufferedReader(fReader);//高级流,提供了一个缓冲区;            try {                String string = null;                while((string = bReader.readLine())!=null){                    System.out.println(string);                }                fReader.close();//先关里面的                bReader.close();//再关外面的            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }//一次读一行        } catch (FileNotFoundException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }

BufferWriter

FileWriter fWriter;        try {            fWriter = new FileWriter("f:/Io/test.txt");            BufferedWriter bWriter = new BufferedWriter(fWriter);            bWriter.write("hello file");            bWriter.newLine();            bWriter.write("ok");            fWriter.flush();            bWriter.flush();            fWriter.close();            bWriter.close();        } catch (IOException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }