Java回炉之IO流（二）使用规律

Java回炉之IO流（二）使用规律

文本文件到文本文件

[code]public class TextFile2TextFile {

    public static void main(String[] args) {
        try {

            //因为是文本文件，所以用FileReader和FileWriter
            FileReader fileReader = new FileReader("a.txt");
            FileWriter fileWriter = new FileWriter("b.txt");

            //为了高效，使用带缓冲区的流
            BufferedReader bufferedReader=new BufferedReader(fileReader);
            BufferedWriter bufferedWriter=new BufferedWriter(fileWriter);

            //写入方式：以字节为单位写入数据
            int b=0;
            while((b=bufferedReader.read())!=-1){
                bufferedWriter.write(b);
            }

            //写入方式优化：以行为单位写入数据
            String string=null;
            while((string= bufferedReader.readLine())!=null){
                bufferedWriter.write(string);
            }

            //最后记着从缓冲区写入到文件并关闭流
            bufferedWriter.flush();
            bufferedWriter.close();
            bufferedReader.close();

        } catch (Exception e) {
            e.printStackTrace();
        }

    }

}

键盘输入到文本文件

[code]public class Keyboard2TextFile {

    public static void main(String[] args) {
        try {

            //输入是键盘，使用System.in
            InputStream inputStream =System.in;
            //输出是文本文件，使用FileWriter
            FileWriter fileWriter = new FileWriter("test.txt");

            //为了高效,将输入流封装为转换流
            InputStreamReader inputStreamReader=new InputStreamReader(inputStream);
            //为了高效，使用缓冲流再次封装
            BufferedReader bufferedReader=new BufferedReader(inputStreamReader);
            BufferedWriter bufferedWriter=new BufferedWriter(fileWriter);

            //写入方式：以字节为单位写入数据
            int b=0;
            while((b=bufferedReader.read())!=-1){
                bufferedWriter.write(b);
            }

            //写入方式优化：以行为单位写入数据
            String string=null;
            while((string= bufferedReader.readLine())!=null){
                bufferedWriter.write(string);
            }

            //最后记着从缓冲区写入到文件并关闭流
            bufferedWriter.flush();
            bufferedWriter.close();
            bufferedReader.close();

        } catch (Exception e) {
            e.printStackTrace();
        }

    }

}

文本文件到屏幕

[code]public class TextFile2Screen {

    public static void main(String[] args) {
        try {

            //输入是文件，使用FileReader
            FileReader fileReader= new FileReader("test.txt");
            //输出是屏幕，使用System.out
            OutputStream outputStream=System.out;

            //为了高效,将输出流封装为转换流
            OutputStreamWriter outputStreamWriter = new OutputStreamWriter(outputStream);
            //为了高效，使用缓冲流再次封装
            BufferedReader bufferedReader=new BufferedReader(fileReader);
            BufferedWriter bufferedWriter=new BufferedWriter(outputStreamWriter);

            //写入方式：以字节为单位写入数据
            int b=0;
            while((b=bufferedReader.read())!=-1){
                bufferedWriter.write(b);
            }

            //写入方式优化：以行为单位写入数据
            String string=null;
            while((string= bufferedReader.readLine())!=null){
                bufferedWriter.write(string);
            }

            //最后记着从缓冲区写入到文件并关闭流
            bufferedWriter.flush();
            bufferedWriter.close();
            bufferedReader.close();

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

键盘到屏幕

[code]public class Keyboard2Screen {

    public static void main(String[] args) {
        try {

            //输入是键盘，使用System.in
            InputStream inputStream =System.in;
            //输出是屏幕，使用System.out
            OutputStream outputStream=System.out;

            //为了高效,将输入流封装为转换流
            InputStreamReader inputStreamReader=new InputStreamReader(inputStream);
            OutputStreamWriter outputStreamWriter=new OutputStreamWriter(outputStream);
            //为了高效，使用缓冲流再次封装
            BufferedReader bufferedReader=new BufferedReader(inputStreamReader);
            BufferedWriter bufferedWriter=new BufferedWriter(outputStreamWriter);

            //写入方式：以字节为单位写入数据
            int b=0;
            while((b=bufferedReader.read())!=-1){
                bufferedWriter.write(b);
            }

            //写入方式优化：以行为单位写入数据
            String string=null;
            while((string= bufferedReader.readLine())!=null){
                bufferedWriter.write(string);
            }

            //最后记着从缓冲区写入到文件并关闭流
            bufferedWriter.flush();
            bufferedWriter.close();
            bufferedReader.close();

        } catch (Exception e) {
            e.printStackTrace();
        }

    }

}

带字符集的文件到文件

[code]public class TextFile2TextFileWithCharset {

    public static void main(String[] args) {
        try {

            //输入是文本文件，所以用FileReader
            FileReader fileReader = new FileReader("a.txt");
            //输出虽是文本文件，但制定了字符集则不能使用FileWriter，需要使用OutputStreamWriter
            OutputStreamWriter outputStreamWriter= new OutputStreamWriter(new FileOutputStream("b.txt"),"utf-8");

            //为了高效，使用带缓冲区的流
            BufferedReader bufferedReader=new BufferedReader(fileReader);
            BufferedWriter bufferedWriter=new BufferedWriter(outputStreamWriter);

            //写入方式：以字节为单位写入数据
            int b=0;
            while((b=bufferedReader.read())!=-1){
                bufferedWriter.write(b);
            }

            //写入方式优化：以行为单位写入数据
            String string=null;
            while((string= bufferedReader.readLine())!=null){
                bufferedWriter.write(string);
            }

            //最后记着从缓冲区写入到文件并关闭流
            bufferedWriter.flush();
            bufferedWriter.close();
            bufferedReader.close();

        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}