Java IO API记录

文件路径：

public static final String FILEPATH= File.separator+"Users"+ File.separator+"xuminzhe"+
            File.separator+"Documents"+File.separator+"io";

1.创建文件

---

public static void main(String[] args) {
        File file=new File(Constant.FILEPATH+File.separator+"io.text");
        try {
            boolean newFile = file.createNewFile();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

2.查找指定目录下文件

---

public static void main(String[] args) {
        File file=new File(Constant.FILEPATH);
        File[] str = file.listFiles();
        for (int i = 0; i < str.length; i++) {
            System.out.println(str[i]);
        }
    }

3.文件流-写入

---

String filename=Constant.FILEPATH+ File.separator+"HELLO.text";
        File file=new File(filename);
        OutputStream outputStream=new FileOutputStream(file,true);
        byte[] bytes = "你好".getBytes();
        for (int i = 0; i < bytes.length; i++) {
            outputStream.write(bytes[i]);
        }
        outputStream.close();

4.文件流-读取

---

public static void main(String[] args) throws IOException {
        String filename=Constant.FILEPATH+ File.separator+"HELLO.text";
        File file=new File(filename);
        InputStream inputStream=new FileInputStream(file);
        /**
         * 单字节读取
         */
        {
            byte[] bytes = new byte[1024];
            int read1;
            int count =0;
            while((read1 = inputStream.read())!=-1){
                bytes[count++]=(byte) read1;
            }
            System.out.println(new String(bytes));
        }
        /**
         * 多字节读取
         */
        {
            byte[] bytes=new byte[(int) file.length()];
            int read;
            while((read=inputStream.read(bytes))!=-1){
                System.out.println(new String (bytes));
            }
        }
    }

5.字符流-写入

---

String filename=Constant.FILEPATH+ File.separator+"HELLO.text";
        File file=new File(filename);
        Writer writer=new FileWriter(file,true);
        String str="
hello";
        writer.write(str);
        writer.close();

6.字符流-读取

---

public static void main(String[] args) throws IOException {
        String filename=Constant.FILEPATH+ File.separator+"HELLO.text";
        File file=new File(filename);
        Reader read=new FileReader(file);
        char[] ch=new char[100];
        int temp=0;
        int count=0;
        while((temp=read.read())!=(-1)){
            ch[count++]=(char)temp;
        }
        read.close();
        System.out.println("内容为"+new String(ch,0,count));
    }

7.转换流-写入  将输出的字符流转化为字节流

---

public static void main(String[] args) throws IOException {
        String filename=Constant.FILEPATH+ File.separator+"HELLO.text";
        File file=new File(filename);
        Writer writer=new java.io.OutputStreamWriter(new FileOutputStream(file,true));
        writer.write("kobe");
        writer.close();
    }

8.转换流-读取 将输入的字节流转换为字符流

---

public static void main(String[] args) throws IOException {
        String filename=Constant.FILEPATH+ File.separator+"HELLO.text";
        File file=new File(filename);
        Reader read = new InputStreamReader(new FileInputStream(file));
        char[] b=new char[100];
        int len=read.read(b);
        System.out.println(new String(b,0,len));
        read.close();
    }

9.对象流

---

static String filename=Constant.FILEPATH+ File.separator+"HELLO.text";
    static File file=new File(filename);
    public static void main(String[] args) throws Exception {
        serializable(file);
        deserializable(file);
    }
    /**
     * 反序列化
     * @param file
     * @throws IOException
     * @throws ClassNotFoundException
     */
    private static void deserializable(File file) throws IOException, ClassNotFoundException {
        ObjectInputStream stream=new ObjectInputStream(new FileInputStream(file));
        Person o = (Person) stream.readObject();
        System.out.println(o.toString());
    }

    /**
     * 序列化对象
     * @param file
     * @throws IOException
     */
    private static void serializable(File file) throws IOException {
        ObjectOutputStream outputStream=new ObjectOutputStream(new FileOutputStream(file,true));
        outputStream.writeObject(new Person("xmz",13));
        outputStream.close();
    }

10.缓冲字符流-读取

---

public static void main(String[] args) throws IOException {
        String filename=Constant.FILEPATH+ File.separator+"HELLO.text";
        File file=new File(filename);
        BufferedReader bufferedReader=new BufferedReader(new FileReader(file));
        String line;
        while((line=bufferedReader.readLine())!=null){//读取一个文本行
            System.out.println(line);
        }
        bufferedReader.close();
    }

11.缓冲字符流-写入

---

public static void main(String[] args) throws IOException {
        String filename=Constant.FILEPATH+ File.separator+"HELLO.text";
        File file=new File(filename);
        FileWriter fileWriter=new FileWriter(file);
        /**
         * 为了提高写入的效率，使用了字符流的缓冲区。
         * 创建了一个字符写入流的缓冲区对象，并和指定要被缓冲的流对象相关联。
         */
        BufferedWriter bufferedWriter=new BufferedWriter(fileWriter);
        bufferedWriter.write("jordan乔丹");
        bufferedWriter.newLine();//换行
        bufferedWriter.write("kobe蜗壳");
        bufferedWriter.write("wade韦德");
        bufferedWriter.flush();
        bufferedWriter.close();

    }

12 管道流-可用于线程通信

---

static class Send implements Runnable{
        private PipedOutputStream out=null;
        public Send() {
            out=new PipedOutputStream();
        }
        public PipedOutputStream getOut(){
            return this.out;
        }
        public void run(){
            String message="hello，xmz";
            try{
                out.write(message.getBytes());
            }catch (Exception e) {
                e.printStackTrace();
            }try{
                out.close();
            }catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 接受消息类
     * */
    static class Recive implements Runnable{
        private PipedInputStream input=null;
        public Recive(){
            this.input=new PipedInputStream();
        }
        public PipedInputStream getInput(){
            return this.input;
        }
        public void run(){
            byte[] b=new byte[1000];
            int len=0;
            try{
                len=this.input.read(b);
            }catch (Exception e) {
                e.printStackTrace();
            }try{
                input.close();
            }catch (Exception e) {
                e.printStackTrace();
            }
            System.out.println("接受的内容为 "+(new String(b,0,len)));
        }
    }

    public static void main(String[] args) throws IOException {
        Send send=new Send();
        Recive recive=new Recive();
        try{
        //管道连接
        send.getOut().connect(recive.getInput());
        }catch (Exception e) {
            e.printStackTrace();
        }
        new Thread(send).start();
        new Thread(recive).start();
    }