0. 字節(jié)流與二進(jìn)制文件
   ==========================

我的代碼

class Student {
	private int id;
	private String name;
	private int age;
	private double grade;

	public Student() {

	}
	public Student(int id, String name, int age, double grade) {
		this.id = id;
		this.setName(name);
		this.setAge(age);
		this.setGrade(grade);
	}
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		if (name.length() > 10) {
			throw new IllegalArgumentException("name's length should <=10 " + name.length());
		}
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		if (age <= 0) {
			throw new IllegalArgumentException("age should >0 " + age);
		}
		this.age = age;
	}
	public double getGrade() {
		return grade;
	}
	public void setGrade(double grade) {
		if (grade < 0 || grade > 100) {
			throw new IllegalArgumentException("grade should be in [0,100] " + grade);
		}
		this.grade = grade;
	}
	@Override
	public String toString() {
		return "Student [id=" + id + ", name=" + name + ", age=" + age + ", grade=" + grade + "]";
	}
}

public class Main {
	public static void main(String[] args)
          {         
             String fileName="d:\\student.data";
              try(DataOutputStream dos=new DataOutputStream(new FileOutputStream(fileName)))
             {
                  Student[] stu=new Student[3];
                  stu[0]=new Student(1,"zhangsan",19,65.0);
                  stu[1]=new Student(2,"lisi",19,75.0);
                  stu[2]=new Student(3,"wangwu",20,85.0);
                  for(Student stu1:stu) {
                     dos.writeInt(stu1.getId());
                     dos.writeUTF(stu1.getName());
                     dos.writeInt(stu1.getAge());
                     dos.writeDouble(stu1.getGrade());
                }
                 
            } catch (FileNotFoundException e) {
                e.printStackTrace();
                 System.out.println("1");
            } catch (IOException e) {
                 e.printStackTrace();
               System.out.println("2");
            }
            try(DataInputStream dis=new DataInputStream(new FileInputStream(fileName)))
             {
                while(dis!=null) {
                    int id=dis.readInt();
                    String name=dis.readUTF();
                    int age=dis.readInt();
                     double grade=dis.readDouble();
                     Student stu=new Student(id,name,age,grade);
                    System.out.println(stu);
                }
                 
                
            } catch (FileNotFoundException e) {
                e.printStackTrace();
                 System.out.println("3");
            } catch (IOException e) {
                e.printStackTrace();
                System.out.println("4");
           }
             
         }

我的總結(jié)

學(xué)會(huì)了使用try..with...resouces關(guān)閉資源，原來(lái)可以用用finally來(lái)關(guān)閉文件，但也要判斷是否可以關(guān)閉資源的問題。而用try…with…resource可以解決該問題，當(dāng)try語(yǔ)句塊運(yùn)行結(jié)束時(shí)，相應(yīng)資源會(huì)被自動(dòng)關(guān)閉。這是因?yàn)镕ileInputStream 實(shí)現(xiàn)了java中的java.lang.AutoCloseable。所有實(shí)現(xiàn)了這個(gè)接口的類都可以在try-with-resources結(jié)構(gòu)中使用。 

1. 字符流與文本文件
   ==========================

我的代碼

public class Main {
	public static void main(String[] args) throws IOException {
		String FileName = "D:\\TSBrowserDownloads\\Students.txt";
		BufferedReader br = null;
		try {
			br = new BufferedReader(new InputStreamReader(new FileInputStream(FileName), "UTF-8"));
			String line = null;
			while ((line = br.readLine()) != null)
				System.out.println(line);
		} finally {
			if (br != null) {
				br.close();
			}
		}
	}

}
public static void ListreadStudents(String fileName){
             ArrayList<Student> StudentList=new ArrayList<Student>();
            BufferedReader br = null;
            try {
                br = new BufferedReader(new InputStreamReader(new FileInputStream(fileName),"UTF-8"));
               while(br!=null) {
                    String line=br.readLine();
                    String[] stu=line.split("\\s+");
                    int id=Integer.parseInt(stu[0]);
                     String name=stu[1];
                     int age=Integer.parseInt(stu[2]);
                     double grade=Double.parseDouble(stu[3]);
                     Student Stu=new Student(id,name,age,grade);
                    StudentList.add(Stu);          
                }                
            } finally{
                if (br!=null){
                    br.close();
                 }
             }
 }

我的總結(jié)

要以UTF-8打開文件，否則會(huì)亂碼。BufferedReader只用read和ReadLine方法，得用實(shí)驗(yàn)提到的"\\s+"的方法將讀到的一整行用分隔符來(lái)分開，再用類型轉(zhuǎn)換來(lái)讀。

2.緩沖流

我的代碼

public class test {
	@Test
	public void test() {
		String FILENAME = "test.txt";
		long begin = System.currentTimeMillis();
		Scanner scanner = null;
		try {
			scanner = new Scanner(new File(FILENAME));
			while (scanner.hasNextLine()) {// 只是讀出每一行，不做任何處理
				scanner.nextLine();
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} finally {
			scanner.close();
		}
		long end = System.currentTimeMillis();
		System.out.println("last " + (end - begin));
		System.out.println("read using Scanner done");
	}

	@Test
	public void Bufftest() {
		String FILENAME = "test.txt";
		long begin = System.currentTimeMillis();
		BufferedReader br = null;
		try {
			br = new BufferedReader(new FileReader(new File(FILENAME)));
			while (br.readLine() != null) {
			}
			;// 只是讀出，不進(jìn)行任何處理
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				br.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		long end = System.currentTimeMillis();
		System.out.println("last " + (end - begin));
		System.out.println("read using BufferedReader done");
	}
}

我的總結(jié)

緩沖流BufferedReader的方法要比Scanner的方法快很多