File I/O

File类

　File类访问文件属性

　　

　File类的常用方法

　　

IO流

　流

　　

　　

　文件的读写

　　

　使用FileInputStream读文本文件

　　

　　

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

public class TestFileInputStream {
    public static void main(String[] args) {
        // 1、创建字节输入流
        InputStream fis = null;
        try {
            fis = new FileInputStream("d:/我的青春我做主.txt");
            // 2、实现读取操作
            // int data; // 存储读到的字节
            // while ((data = fis.read()) != -1) {
            // System.out.print((char) data);
            // }
            byte[] words = new byte[1024];
            int len; // 存储读入数组的长度
            while ((len = fis.read(words)) != -1) {
                System.out.print(new String(words, 0, len));
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 3、关闭流
            try {
                if (fis != null) {
                    fis.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

　使用FileOutputStream写文本文件

　　

　　

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;

public class TestFileOutputStream {

    public static void main(String[] args) {
        // 1、创建字节输出流
        OutputStream fis = null;
        try {
            fis = new FileOutputStream(new File("d:/Hello.txt"));
            // 2、执行写操作
            String str = "好好学习Java！"; // 要写出的字符串
            byte[] words = str.getBytes(); // 将字符串转换为字节数组
            fis.write(words);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
            System.out.println("创建文件是出错！");
        } finally {
            // 3、关闭流
            if (fis != null) {
                try {
                    fis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

}

　使用FileReader读取文件

　　

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;

public class TestFileReader {

    public static void main(String[] args) {
        // 1、创建字符流对象
        Reader fr = null;
        StringBuffer sb = null;
        try {
            fr = new FileReader("d:/我的青春我做主.txt");
            // 2、读取文本文件
            // int word; // 接收读取到的字符
            // while ((word = fr.read()) != -1) {
            // System.out.print((char) word);
            // }
            char[] words = new char[1024]; // 存储读取到的字符
            sb = new StringBuffer();
            int len = fr.read(words); // 读取到字符数组中
            while (len != -1) {
                sb.append(words);
                len = fr.read(words);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 3、关闭流
            if (fr != null) {
                try {
                    fr.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        System.out.println(sb.toString());
    }
}

　BufferedReader类

　　

　　

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;

public class TestBufferedReader {

    public static void main(String[] args) {
        // 1、创建字符流对象
        Reader fr = null;
        BufferedReader br = null;
        try {
            fr = new FileReader("d:/我的青春我做主.txt");
            br = new BufferedReader(fr);
            // 2、读取文本文件
            String line = null; // 接收读取到的信息
            while ((line = br.readLine()) != null) {
                System.out.println(line);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 3、关闭流
            if (br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (fr != null) {
                try {
                    fr.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

 　使用FileWriter写文件

　　

import java.io.FileWriter;
import java.io.IOException;
import java.io.Writer;

public class TestFileWriter {

    public static void main(String[] args) {
        // 1、创建流
        Writer fw = null;
        try {
            fw = new FileWriter("d:/简介.txt");
            // 2、写入信息
            fw.write("我爱我的团队！");
            fw.flush();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 3、关闭流
            if (fw != null) {
                try {
                    fw.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

}

　BufferedWriter类

　　

　　

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Writer;

public class TestBufferedWriter {

    public static void main(String[] args) {
        // 1、创建流
        Writer fw = null;
        BufferedWriter bw = null;
        try {
            fw = new FileWriter("d:/hello.txt");
            bw = new BufferedWriter(fw);
            // 2、写入信息
            bw.write("大家好！");
            bw.newLine();
            bw.write("我正在学习BufferedWriter。");
            bw.newLine();
            bw.write("请多指教！");
            bw.flush();
        } catch (IOException e) {
            e.printStackTrace();
        }finally{
            // 3、关闭流
            if (bw!=null) {
                try {
                    bw.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

}

　读写二进制文件

　　

　　

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

public class ReadAndWriteBinaryFile {

    public static void main(String[] args) {
        // 1、创建流
        DataInputStream dis = null;
        DataOutputStream dos = null;
        try {
            dis = new DataInputStream(
                    new FileInputStream("d:/StringDemo.class"));
            dos = new DataOutputStream(
                    new FileOutputStream("d:/FileCopy.class"));
            // 2、实现读写操作
            int temp;
            while ((temp = dis.read()) != -1) {
                dos.write(temp);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 3、关闭流
            if (dis != null) {
                try {
                    dis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (dos != null) {
                try {
                    dos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

}

序列化

　　

　　

import java.io.Serializable;

public class Student implements Serializable {
    private String name;
    private int age;
    private transient String gender;

    public Student() {
    }

    public Student(String name, int age, String gender) {
        super();
        this.name = name;
        this.age = age;
        this.gender = gender;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

}

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;

public class TestSerializable {

    public static void main(String[] args) {
        // 1、创建一个需要序列化的学生对象
        Student stu = new Student("王宝宝", 18, "男");
        // 2、创建一个对象输出流
        OutputStream os = null;
        ObjectOutputStream oos = null;
        // 3、创建对象输入流
        InputStream is = null;
        ObjectInputStream ois = null;
        try {
            os = new FileOutputStream("d:/student.bin");
            oos = new ObjectOutputStream(os);
            oos.writeObject(stu);

            is = new FileInputStream("d:/student.bin");
            ois = new ObjectInputStream(is);
            Student stu1 = (Student) ois.readObject();

            System.out.println("学生姓名：" + stu1.getName() + "，年龄："
                    + stu1.getAge() + "，性别：" + stu1.getGender());
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } finally {
            if (oos != null) {
                try {
                    oos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (os != null) {
                try {
                    os.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (ois != null) {
                try {
                    ois.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (is != null) {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

    }

}