IO流之BufferedReader和BufferedWriter

BufferedReader

现成reader

以下代码使用BufferedReader来读取硬盘文本文件：

package com.javalearn.io.buffer; 
 
import java.io.BufferedReader; 
import java.io.FileNotFoundException; 
import java.io.FileReader; 
import java.io.IOException; 
 
public class TestForBufferedReader { 
    public static void main(String[] args) { 
        FileReader fileReader = null; 
        try { 
            fileReader = new FileReader("D:\\typora笔记\\java\\io流\\临时文件夹\\新.java"); 
            BufferedReader reader = new BufferedReader(fileReader);  // fileReader为节点流，reader为包装流/处理流 
            String s = " "; 
            while((s=reader.readLine())!=null) { // readLine读到末尾的时候返回null 
                System.out.println(s);  // readLine不会读出换行符，因此需要打印时换行 
            } 
            if (reader != null) { 
                try { 
                    reader.close();  // 包装流的close包含了节点流的close 
                } catch (IOException e) { 
                    e.printStackTrace(); 
                } 
            } 
        } catch (FileNotFoundException e) { 
            e.printStackTrace(); 
        } catch (IOException e) { 
            e.printStackTrace(); 
        } 
 
    } 
} 
 

输出结果：

public class Hello { 
    public static void main(String[] args) { 
        System.out.println("Hello world"); 
    } 
} 

构造reader

上文中，FileReader对象作为参数传入BufferedReader的构造函数中，实际上可以把FileInputStream转换为Reader，再传入BufferedReader的构造函数中：

package com.javalearn.io.change; 
 
import java.io.*; 
 
public class TestForMultiSon { 
    public static void main(String[] args) throws IOException { 
        BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream("D:\\typora笔记\\java\\io流\\临时文件夹\\新.java")));  // 节点流和包装流是相对关系。字节流转为字符流，作为参数送入BufferedReader的构造函数。 
        String line = null; 
        while ((line = br.readLine())!=null) { 
            System.out.println(line); 
        } 
        br.close(); 
    } 
} 
 

输出结果：

public class Hello { 
    public static void main(String[] args) { 
        System.out.println("Hello world"); 
    } 
} 

BufferedWriter

现成writer

以下代码使用BufferedWriter往硬盘写数据：

package com.javalearn.io.bufferedwriter; 
 
import java.io.BufferedWriter; 
import java.io.FileWriter; 
 
public class TestForBufferedWriter { 
    public static void main(String[] args) throws Exception{ 
        BufferedWriter writer = new BufferedWriter(new FileWriter("file1")); 
        writer.write("hello world\nhello kitty"); 
        writer.flush(); 
        writer.close(); 
    } 
} 
 

输出文件内容：

hello world 
hello kitty 

构造writer

以下代码也是往硬盘写数据，不过构造函数中的writer是间接构造出来的：

package com.javalearn.io.bufferedwriter; 
 
import java.io.BufferedWriter; 
import java.io.FileOutputStream; 
import java.io.FileWriter; 
import java.io.OutputStreamWriter; 
 
public class TestForBufferedWriter { 
    public static void main(String[] args) throws Exception{ 
        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("file1"))); 
        writer.write("我现在很饿");  // 往硬盘写 
        writer.flush(); 
        writer.close(); 
    } 
} 
 

输出文件内容：

我现在很饿