Java回炉之IO流（二）使用规律

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源代码下载

文本文件到文本文件

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

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

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

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

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();        }    }}