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 */