java学习笔记（9-IO流）

1.FileWriter

package daigua8;
import java.io.FileWriter;
import java.io.IOException;
/*
输出流写数据的步骤：
*       A:创建输出流对象
*       B:调用输出流对象的写数据的方法
*       C:释放资源
*/
public class FileWriterDemo {
    public static void main(String[] args) throws IOException {
        // 创建一个输出流对象
        FileWriter fw = new FileWriter("/Users/dengrunting/Desktop/test.txt");
        // 写入信息到文件
        fw.write("你好，我是你爸爸！");
        // 从内存缓冲区，压入到磁盘
        fw.flush();
        // 关闭输出流对象，系统释放相关资源
        fw.close();
    }
}

2.FileReader

package daigua8;
import java.io.FileReader;
import java.io.IOException;

public class FileReaderDemo {
    public static void main(String[] args) throws IOException{
        // 创建一个输入流对象
        FileReader fr = new FileReader("/Users/dengrunting/Documents/eclipse-workspace/my_demo/src/daigua8/FileReaderDemo.java");
        int ch;
        while ((ch = fr.read()) != -1) {
            System.out.print((char)ch);
        }
        fr.close();
    }
}

3.文件复制（单字节）

package com.daigua;
import java.io.FileWriter;
import java.io.FileReader;
import java.io.IOException;

public class FileCopy {
    public static void main(String[] args) throws IOException{
        // 创建输入输出流对象
        FileReader fr = new FileReader("/Users/dengrunting/Desktop/java视频/test.txt");
        FileWriter fw = new FileWriter("/Users/dengrunting/Desktop/java视频/test_copy.txt");
        
        // 边读边写
        int ch;
        while ((ch = fr.read()) != -1) {
            System.out.print((char)ch);
            fw.write((char)ch);
        }
        // 刷新缓冲区
        fw.flush();
        
        fw.close();
        fr.close();
    }

}

4.文件复制（多字节）

package com.daigua;
import java.io.FileWriter;
import java.io.FileReader;
import java.io.IOException;

public class FileCopy2 {
    public static void main(String[] args) throws IOException{
        // 创建输入输出流对象
        FileReader fr = new FileReader("./src/com/daigua/FileCopy.java");
        FileWriter fw = new FileWriter("./src/com/daigua/copy.FileCopy.java");
        
        // 边读边写,一次读入1024字节
        char[] chs = new char[1024];
        int ch;
        while ((ch = fr.read(chs)) != -1) {
            System.out.print(chs);
            fw.write((char)ch);
        }
        // 刷新缓冲区
        fw.flush();
        
        fw.close();
        fr.close();
    }

}

5.缓冲流复制文件

package com.daigua;
import java.io.FileWriter;
import java.io.FileReader;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;

public class BufferedReaderDemo {
    public static void main(String[] args) throws IOException{
        // 创建输入输出流对象
        BufferedReader fr = new BufferedReader(new FileReader ("./src/com/daigua/BufferedReaderDemo.java"));
        BufferedWriter fw = new BufferedWriter(new FileWriter("./src/com/daigua/copy.FileCopy2.java"));
        
        // 边读边写,一次读入1024字节
        char[] chs = new char[1024];
        int len;
        while ((len = fr.read(chs)) != -1) {
            System.out.print(chs);
            fw.write(chs, 0, len);
        }
        // 刷新缓冲区
        fw.flush();
        
        fw.close();
        fr.close();
    }

}

6.缓冲流特有方法复制文件

package com.daigua;
import java.io.FileWriter;
import java.io.FileReader;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;

public class BufferedStreamDemo {
    public static void main(String[] args) throws IOException{
        // 创建输入输出流对象
        BufferedReader fr = new BufferedReader(new FileReader ("./src/com/daigua/BufferedReaderDemo.java"));
        BufferedWriter fw = new BufferedWriter(new FileWriter("./src/com/daigua/copy.FileCopy3.java"));
        
        // 边读边写,以此读取一行
        String line;
        while ((line = fr.readLine()) != null) {
            System.out.print(line + "\r\n");
//          fw.write(line + "\r\n");
            fw.write(line);
            fw.newLine();
            fw.flush();  // 读一行写一行
        }
        
        fw.close();
        fr.close();
    }

}