IO流之FileReader和FileWriter

FileReader

以下代码使用FileReader读取数据：

package com.javalearn.io.filereader; 
 
import java.io.FileNotFoundException; 
import java.io.FileReader; 
import java.io.IOException; 
 
public class TestForFileReader { 
    public static void main(String[] args) { 
        FileReader reader = null;  // 以防忘记，这里注意，Reader以字符为单位读取数据 
        try { 
            reader = new FileReader("file1"); 
            char[] chars = new char[4];  // 字符数组，与字节数组类似 
            int count = 0; 
            while ((count = reader.read(chars))!=-1) {  // 每次读多个字符 
                System.out.print(new String(chars,0,count)); 
            } 
        } catch (FileNotFoundException e) { 
            e.printStackTrace(); 
        } catch (IOException e) { 
            e.printStackTrace(); 
        } finally { 
            if (reader != null) { 
                try { 
                    reader.close(); 
                } catch (IOException e) { 
                    e.printStackTrace(); 
                } 
            } 
        } 
    } 
} 
 

输出结果：

abcdef 

FileWriter

以下代码使用FileWriter把数据写入硬盘：

package com.javalearn.io.filewriter; 
 
import java.io.FileWriter; 
import java.io.IOException; 
 
public class TestForJavaWriter { 
    public static void main(String[] args) { 
        FileWriter writer = null; 
        try { 
            writer = new FileWriter("file1");  // 无此文件则新建。默认先清空原文件再写入，有参数true则追加，不清空 
            char[] chars = {'我','想','打','游','戏'}; 
            writer.write(chars);  //可传入字符数组 
            writer.write("我是什么都会的猪大肠");  //也可传入字符串 
            writer.flush();  //别忘了刷新 
        } catch (IOException e) { 
            e.printStackTrace(); 
        } finally { 
            if (writer != null) { 
                try { 
                    writer.close(); 
                } catch (IOException e) { 
                    e.printStackTrace(); 
                } 
            } 
        } 
    } 
} 
 

文件输出结果：

我想打游戏我是什么都会的猪大肠 

文本拷贝

以下代码使用FileReader和FileWriter来拷贝文件：

package com.javalearn.io.copy2; 
 
import java.io.FileNotFoundException; 
import java.io.FileReader; 
import java.io.FileWriter; 
import java.io.IOException; 
 
public class TestForCopy { 
    public static void main(String[] args) { 
        FileReader in = null; 
        FileWriter out = null; 
        try { 
            in = new FileReader("D:\\javaProject\\Hello\\src\\Hello.java"); 
            out = new FileWriter("D:\\typora笔记\\java\\io流\\临时文件夹\\新.java"); 
            char[] chars = new char[1024*512]; // 1MB 
            int count = 0; 
            while ((count = in.read(chars))!=-1) { 
                out.write(chars,0,count); 
            } 
            out.flush();  // 别忘了刷新 
        } catch (FileNotFoundException e) { 
            e.printStackTrace(); 
        } catch (IOException e) { 
            e.printStackTrace(); 
        } finally { 
            if (in != null) { 
                try { 
                    in.close(); 
                } catch (IOException e) { 
                    e.printStackTrace(); 
                } 
            } 
            if (out != null) { 
                try { 
                    out.close(); 
                } catch (IOException e) { 
                    e.printStackTrace(); 
                } 
            } 
        } 
    } 
}