Java中的IO整理

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创建文件

public static void createNewFile() throws IOException {        String fileName = "D:" + File.separator + "hello.txt";        File f = new File(fileName);        f.createNewFile();    }

删除文件

public static void deleteFile() {        String fileName = "D:" + File.separator + "hello.txt";        File f = new File(fileName);        if (f.exists()) {            f.delete();        }    }

新建文件夹

public static void createNewDir() {        String fileName = "F:" + File.separator + "ff";        File f = new File(fileName);        f.mkdir();    }

递归遍历目录

public static void traversalDir(String filePath) {        File dir = new File(filePath);        File[] files = dir.listFiles();        for (File file : files) {            if (file != null) {                if (file.isDirectory()) {                    traversalDir(file.getAbsolutePath());                } else {                    System.out.println(file.getAbsolutePath());                }            }        }    }

写入文件

    public static void writeString2File() throws IOException {        String filePath = "D:" + File.separator + "hello.txt";        File f = new File(filePath);        OutputStream out = new FileOutputStream(f, false);        String str = "abcdefghijklmnopqs";        byte[] bytes = str.getBytes();        for (int i = 0; i < bytes.length; i++) {            out.write(bytes[i]);        }        out.close();    }

读文件

    public static void readFile() throws IOException {        String filePath = "D:" + File.separator + "hello.txt";        File f = new File(filePath);        InputStream in = new FileInputStream(f);        byte[] bytes = new byte[1024];        int temp = 0;        int count = 0;        while ((temp = in.read()) != -1) {            bytes[count++] = (byte) temp;        }        in.close();        System.out.println(new String(bytes));    }

对象序列化

    public class User implements Serializable{    private static final long serialVersionUID = 1L;    private transient int id = 123;    private transient String name = "abc";    private String password = "12345";    public User(int id, String name, String password) {        this.id = id;        this.name = name;        this.password = password;    }    public User() {    }    public int getId() {        return id;    }    public void setId(Integer id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getPassword() {        return password;    }    public void setPassword(String password) {        this.password = password;    }    private void privateMethod() {        System.out.println("access the private method");    }    @Override    public String toString() {        return "User{" +                "id=" + id +                ", name='" + name + '\'' +                ", password='" + password + '\'' +                '}';        }    }    public static void serializClass() throws Exception {        String filePath = "D:" + File.separator + "seri.txt";        File f = new File(filePath);        ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(f));        out.writeObject(new User(123,"jim","abcde"));        out.close();    }

反序列化

    public static void deserializClass() throws Exception {        String filePath = "D:" + File.separator + "seri.txt";        File f = new File(filePath);        ObjectInputStream in = new ObjectInputStream(new FileInputStream(f));        User user = (User) in.readObject();        in.close();        System.out.println(user);    }

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