第五课：流与其他

Posted 2022-12-03 Vanau

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首先参考自：http://blog.csdn.net/hguisu/article/details/7418161

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一.文件输入输出字节流

/*
*文件名：fileInputStreamTest.java
*功能：读取文件并显示到控制台
*/
package IOTest;
import java.io.*;
public class fileInputStreamTest 

    public static void main(String[] args) throws IOException 
    
        FileInputStream fileInputStream=new FileInputStream("C:\\\\Users\\\\f\\\\Desktop\\\\WorkingSpace\\\\r.txt");
        byte[] buf=new byte[1024];
        int length=0;
        while ((length=fileInputStream.read(buf))>0)
        
            System.out.println(new String(buf,0,length));
        
        fileInputStream.close();
    

/*
*文件名：fileOutputStreamTest
*功能：读取文件并将文件写入另一个文件中（复制）
*/
package IOTest;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class fileOutputStreamTest 

    public static void main(String[] args) throws IOException 
    
        FileInputStream fileInputStream=new FileInputStream("C:\\\\Users\\\\f\\\\Desktop\\\\WorkingSpace\\\\r.txt");
        FileOutputStream fileOutputStream=new FileOutputStream("C:\\\\Users\\\\f\\\\Desktop\\\\WorkingSpace\\\\w.txt");
        byte[] buf=new byte[1024];
        int length=fileInputStream.read(buf,0,buf.length);
        for (byte b : buf) 
            fileOutputStream.write(b);
           
        fileInputStream.close();
        fileOutputStream.close();
    

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二.输入输出字符流

/*
*文件名：bufferedReaderTest.java
*功能：读取文件到控制台显示
*/
package IOTest;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

public class bufferedReaderTest 

    public static void main(String[] args) throws IOException 
    
        BufferedReader bufferedReader=new BufferedReader(new FileReader("C:\\\\Users\\\\f\\\\Desktop\\\\WorkingSpace\\\\r.txt"));
        String line=null;
        while ((line=bufferedReader.readLine())!=null) 
        
            System.out.println(line);
        
    

/*
*文件名：bufferedWriterTest.java
*功能：读取文件并写入到另一个文件（复制）
*/
package IOTest;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class bufferedWriterTest 

    public static void main(String[] args) throws IOException 
    
        BufferedReader bufferedReader=new BufferedReader(new FileReader("C:\\\\Users\\\\f\\\\Desktop\\\\WorkingSpace\\\\r.txt"));
        BufferedWriter bufferedWriter=new BufferedWriter(new FileWriter("C:\\\\Users\\\\f\\\\Desktop\\\\WorkingSpace\\\\w.txt"));
        String line=null;
        while ((line=bufferedReader.readLine())!=null) 
        
            bufferedWriter.write(line);
            bufferedWriter.newLine();           
        
        bufferedWriter.close();
        bufferedReader.close();
    

三.对象流

/*
*文件名：User.java
*功能：对象类信息
*/
package IOTest;
import java.io.*;

public class User implements Serializable

    String userName;
    String password;
    public User(String userName,String password)
    
        this.userName=userName;
        this.password=password; 
    
    @Override
    public String toString() 
    
        return "[用户名："+this.userName+"----密码："+this.password+"]";
    

/*
*文件名：UserTest.java
*功能：写对象和读对象测试
*/
package IOTest;
import java.io.*;

public class UserTest 

    public static void main(String[] args) throws IOException, ClassNotFoundException 
    
        User user1=new User("Alice", "1234");
        writeObj(user1);
        User user2=(User)readObj();
        System.out.println("读取对象的信息："+user2);
    
    //写对象到文件（序列化）
    public static void  writeObj(User user) throws IOException 
    
        ObjectOutputStream objOut=new ObjectOutputStream(new FileOutputStream("C:\\\\Users\\\\f\\\\Desktop\\\\WorkingSpace\\\\r.txt"));
        objOut.writeObject(user);
        objOut.close();
    
    //读取文件中的对象（反序列化）
    public static Object readObj() throws IOException, ClassNotFoundException
    
        ObjectInputStream objIn=new ObjectInputStream(new FileInputStream("C:\\\\Users\\\\f\\\\Desktop\\\\WorkingSpace\\\\r.txt"));
        return objIn.readObject();
    

/*
*文件名：UsersTest.java
*功能：写对象数组和读对象数组
*/
package IOTest;
import java.io.*;

public class UsersTest 

    public static void main(String[] args) throws IOException, ClassNotFoundException 
    
        User[] users=new User[3];
        users[0]=new User("Alice", "1234");
        users[1]=new User("Bob", "12345");
        users[2]=new User("Carl", "123456");
        writeObj(users);
        User[] user2=readObj2();
        for (User user : user2) 
        
            System.out.println(user);
        
        /*      User user1=new User("Alice", "1234");
        writeObj(user1);
        User user2=(User)readObj();
        System.out.println("读取对象的信息："+user1);*/
    
    //写对象到文件（序列化）
    public static void  writeObj(User[] user) throws IOException 
    
        ObjectOutputStream objOut=new ObjectOutputStream(new FileOutputStream("C:\\\\Users\\\\f\\\\Desktop\\\\WorkingSpace\\\\r.txt"));
        objOut.writeObject(user);
        objOut.close();
    
    //读取文件中的对象（反序列化）
    /*  public static Object readObj() throws IOException, ClassNotFoundException
        
            ObjectInputStream objIn=new ObjectInputStream(new FileInputStream("C:\\\\Users\\\\f\\\\Desktop\\\\WorkingSpace\\\\r.txt"));
            return objIn.readObject();
        */
    public static User[] readObj2() throws IOException, ClassNotFoundException
    
        ObjectInputStream objIn=new ObjectInputStream(new FileInputStream("C:\\\\Users\\\\f\\\\Desktop\\\\WorkingSpace\\\\r.txt"));
        User[] newusers=(User[])objIn.readObject(); 
        return newusers;
    

得到结果：