Java IO流--练习

小鱼儿 2022-06-16 01:18 202阅读 0赞

1）将若干个Student对象,若干个Teacher对象,写出到d:/0404/a.txt中  
2）将该文件中所有Student对象反序列化回来装入List, 所有的Teacher对象反序列化回来转入另外一个List

**运用知识点：对象流，文件流**

代码：  
逻辑—–>建立一个Person类，并实现Serializable。再让Student和Teacher类继承Person。（当然这里没必要，可以直接建立Student和Teacher类）

**Person类**

package Homework;
    
    import java.io.Serializable;
    
    public class Person implements Serializable {
        
        private static final long serialVersionUID = 1L;
        private String name;
        private String sex;
        private int age;
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public String getSex() {
            return sex;
        }
        public void setSex(String sex) {
            this.sex = sex;
        }
        public int getAge() {
            return age;
        }
        public void setAge(int age) {
            this.age = age;
        }
        @Override
        public String toString() {
            return "Person [name=" + name + ", sex=" + sex + ", age=" + age + "]";
        }
        public Person(String name, String sex, int age) {
            super();
            this.name = name;
            this.sex = sex;
            this.age = age;
        }
        public Person() {
            super();
        }
    
    }

**Student类**

package Homework;
    
    public class Student extends Person {
        
        public Student(String name,String sex,int age){
            super(name, sex, age);
        }
        public Student(){}
        @Override
        public String toString() {
            return "Student [getName()=" + getName() + ", getSex()=" + getSex() + ", getAge()=" + getAge() + "]";
        }   
    }

**Teacher类**

package Homework;
    
    public class Teacher extends Person {
        
        public Teacher(String name,String sex,int age){
            super(name, sex, age);
        }
        public Teacher(){}
        @Override
        public String toString() {
            return "Teacher [getName()=" + getName() + ", getSex()=" + getSex() + ", getAge()=" + getAge() + "]";
        }
    }

**测试类**

package Homework;
    
    import java.io.File;
    import java.io.FileInputStream;
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.ObjectInputStream;
    import java.io.ObjectOutputStream;
    import java.util.ArrayList;
    
    public class Test1and2 {
        
    
        public static void main(String[] args) {
            //在本工程下创建一个文件夹
            File file=new File("Instance");
            file.mkdirs();
            //在本工程下创建的文件夹下创建一个a.txt文件，用来写入对象
            File file2=new File(file,"a.txt");
    
            //使用对象流写入对象
            ObjectOutputStream oos=null;
            ObjectInputStream ois=null;
            try {
                file2.createNewFile();
    
                //将若干个Student对象,若干个Teacher对象,写入文件中
                oos=new ObjectOutputStream(new FileOutputStream(file2));
                oos.writeObject(new Student("李四","男",20));
                oos.writeObject(new Student("李四2","男",45));
                oos.writeObject(new Student("李四3","男",38));
                oos.writeObject(new Teacher("张三","男",13));
                oos.writeObject(new Teacher("张三","男",50));
                oos.writeObject(new Teacher("张三","男",34));
                oos.flush();
    
                //将该文件中所有Student对象反序列化回来装入List
                ois=new ObjectInputStream(new FileInputStream(file2));
                ArrayList<Student> list=new ArrayList<>();
                ArrayList<Teacher> list2=new ArrayList<>();
    
                //将文件中写入的对象读取出来，并转为对象，存入对应的集合中
                for(int i=0;i<6;i++){
                    if(i<=2){
                        Student student=(Student)ois.readObject();
                        list.add(student);
                    }else {
                        Teacher teacher=(Teacher)ois.readObject();
                        list2.add(teacher);
                    }
                }
    
                //遍历打印出集合中的对象
                for (Student student : list) {
                    System.out.println(student);
                }
                for (Teacher teacher : list2) {
                    System.out.println(teacher);
                }
    
    
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (ClassNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }finally {
                if(ois!=null){
                    try {
                        ois.close();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
                if(oos!=null){
                    try {
                        oos.close();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            }
        }
    }

遍历结果：  
![这里写图片描述][SouthEast]

3）要求从控制台输入两个整数，之后完成两个整数的加法操作

如果输入整数，求和。
    如果输入的不是整数：重新输入，比如ddd

**注意：要求使用标准流，不能使用Scanner类**

代码：

package com.qf.demo2;
    
    import java.io.BufferedReader;
    import java.io.IOException;
    import java.io.InputStreamReader;
    
    public class Test {
    
        public static void main(String[] args) {
            BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
             int sum = 0;
            while(true){
                try {
                    System.out.println("请输入第一个数：");
                    String a = reader.readLine();
    
                    System.out.println("请输入第二个数：");
                    String b = reader.readLine();
    
                    //对输入的内容进行正则匹配，判断是否是数字
                    boolean flag = a.matches("[0-9]+");
                    boolean flag2 = b.matches("\\d+");
    
                    // 如果两次输入的都是数字，那么将两次输入的数据转为整数，并求和，以及退出循环
                    if( flag && flag2){
                        sum = Integer.parseInt(a)+Integer.parseInt(b);
                        break;
                    }else{
                        // 如果两次输入有一个不是数字，则重新输入，进入循环
                        System.out.println("请重新输入,必须只能包含数字");
                    }
    
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
            System.out.println("输入的两个整数和是："+sum);
        }
    }

运行结果：

![这里写图片描述][SouthEast 1]

[SouthEast]: /images/20220616/a4c57cdeaa4849b9991ac7cd7e5a5561.png
[SouthEast 1]: /images/20220616/fff9b232800d4b88960839a36a2a4dce.png