JAVA第09次实验(IO流)
0.字节流与二进制文件
我的代码</span.
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
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="f:\\student.txt";
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) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println("1");
} catch (IOException e) {
// TODO Auto-generated catch block
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) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println("3");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println("4");
}
}
}
我的总结</span.
1.字符流与文本文件:使用PrintWriter(写),BufferedReader(读)
- (1)
我的代码</span.
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();
}
}
}
}
我的总结</span.
直接打开会出现乱码,所以在读取前要把模式改为“UTF-8”;
- (2)
我的代码</span
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();
}
}
}
- (3)
我的代码</span.
String FileName="D:\\TSBrowserDownloads\\Students.txt";
PrintWriter pw=new PrintWriter(new OutputStreamWriter(new FileOutputStream(FileName,true),"UTF-8"));
pw.print("4 陈六 21 93");
pw.close();