Java中流的操作练习

 文件中的学生信息

　　学生信息存储在TXT文件中，我们需要对信息进行基本的,增、删、改、查，全部显示操作。

1、学生类/Student

package com.yujiao.student;

public class Student {
        /**学生id*/
    private int id;
                /**学生姓名*/
    private String name;
                 /**学生年龄*/
    private int age;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    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;
    }

     /**
     * 无参构造方法
     */
    public Student() {
    }
     /**
            * 有参构造方法
            */
    public Student(int id, String name, int age) {
        super();
        this.id = id;
        this.name = name;
        this.age = age;
    }

     /**
            * 重写的toString方法
            */

    @Override
    public String toString() {
        return "Student [id=" + id + ", name=" + name + ", age=" + age + "]";
    }

}

2、学生管理类的接口定义/StudentManagement

package com.yj.student;

import java.util.List;

public interface IStudentManager {
    
   /** 默认文件存放位置*/
    public String DEFAULT_PATH = "E:\Test\student.txt";
    
    /**
     * 获得所有学生信息
     * @return 学生信息的List泛型集合
     */
    public List<Student> list();
    
    /**
     * 根据学生id获取对应的学生对象
     * @param id
     * @return
     */
    public Student get(int id);
    
    /**
     * 根据指定id删除学生信息
     * @param id 学生id
     * @return 删除成功返回true，失败返回false
     */
    public boolean delete(int id);
    
    /**
     * 根据传入学生对象的信息，修改学生
     * 如果传入学生对象的id能够找到对象的信息，那么就修改
     * @param student 学生对象，将需要修改的信息封装在这个对象中
     * @return 修改成功true，否则false
     */
    public boolean update(Student student);
    
    
    /**
     * 传入学生对象，加入到文本信息中
     * @param student 学生对象
     * @return  添加成功true，否则false
     */
    public boolean add(Student student);
    

}

3、学生管理类接口的实现类/MyStudentManagement

package com.yj.student;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.List;

public class StudentManagerImpl implements IStudentManager {

    /** 自定义文本位置的路径 */
    private String Path;

    /**
     * 默认构造方法，给到了默认路径
     */
    public StudentManagerImpl() {
        this.Path = DEFAULT_PATH;
    }

    /**
     * 根据传入的路径读取文本文件
     * 
     * @param path 传入的文件路径
     */
    public StudentManagerImpl(String path) {
        this.Path = path;
    }

    @Override
    public List<Student> list() {
        List<Student> list = new ArrayList<Student>();
        BufferedReader br = null;

        try {
            br = new BufferedReader(new FileReader(this.Path));
            String str = null;
            while ((str = br.readLine()) != null) {
                String[] strs = str.split("\s+");
                int id = Integer.parseInt(strs[0]);
                String name = strs[1];
                int age = Integer.parseInt(strs[2]);

                Student s = new Student(id, name, age);
                list.add(s);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (br != null) {
                    br.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return list;
    }

    @Override
    public Student get(int id) {
        Student stu = null;
        BufferedReader br = null;

        try {
            br = new BufferedReader(new FileReader(this.Path));
            String str = null;
            while ((str = br.readLine()) != null) {
                String[] strs = str.split("\s+");
                int sid = Integer.parseInt(strs[0]);
                String name = strs[1];
                int age = Integer.parseInt(strs[2]);
                if (id == sid) {
                    stu = new Student(sid, name, age);
                    break;
                }

            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (br != null) {
                    br.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return stu;
    }

    @Override
    public boolean delete(int id) {
        //先把文本文档中的内容读取到内存中
        List<Student> stus = list();
        boolean flag = false;
        
//        在集合中找到对象并且删除对应的学生对象
            for (int i = 0; i < stus.size(); i++) {
                Student s = stus.get(i);
                if (s.getId() == id) {
                    flag = true;
                    stus.remove(s);
                    break;
                }
            }    
//            将集合中的内容整个重新写到文本文件中    
            if (flag) {
                PrintWriter out = null;
                try {    
                out = new PrintWriter(Path);
                for (int i = 0; i < stus.size(); i++) {
                    Student s = stus.get(i);
                    String str = s.getId()+" "+s.getName()+" "+s.getAge();
                    out.println(str);
                }
            
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } finally {
            try {
                    out.close();    
            } catch (Exception e) {
                flag = false;
                e.printStackTrace();
            }
        }
     }
        return flag;
    }

    @Override
    public boolean update(Student student) {
        // 先把文本文档中的内容读取到内存中
        List<Student> stus = list();
        boolean flag = false;

//                在集合中找到对象并且删除对应的学生对象
        for (int i = 0; i < stus.size(); i++) {
            Student s = stus.get(i);
            if (s.getId() == student.getAge()) {
                flag = true;
                s.setAge(student.getAge());
                s.setName(student.getName());
                break;
            }
        }
//                    将集合中的内容整个重新写到文本文件中    
        if (flag) {
            PrintWriter out = null;
            try {
                out = new PrintWriter(Path);
                for (int i = 0; i < stus.size(); i++) {
                    Student s = stus.get(i);
                    String str = s.getId() + " " + s.getName() + " " + s.getAge();
                    out.println(str);
                }

            } catch (FileNotFoundException e) {
                flag = false;
                e.printStackTrace();
            } finally {
                try {
                    out.close();
                } catch (Exception e) {
                    flag = false;
                    e.printStackTrace();
                }
            }
        }
        return flag;
    }

    @Override
    public boolean add(Student student) {
//        先把文本文档中的内容读取到内存中    
        boolean flag = false;
        PrintWriter out = null;

        try {
            out = new PrintWriter(new FileWriter(this.Path, true));
            out.println(student.getId() + " " + student.getName() + " " + student.getAge());
            flag = true;
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                out.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }

        }
        return flag;
    }

    public String getPath() {
        return Path;
    }

    public void setPath(String path) {
        this.Path = path;
    }

}

/** 学生id */