Java IO流--转换流InputStreamReader和OutputStreamWriter的使用

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转换流的使用：

1、转换流属于处理流

InputStreamReader :将一个字节的输入流转换为字符的输入流
OutputStreamWriter:将一个字节的输出流转换为字符的输出流

2、提供字节流与字符流之间的转换

3、解码：字节、字节数组—>字符数组，字符串
编码：字符数组，字符串---->字节，字节数组

4、字符集

一、InputStreamReader的使用，具体代码如下：

/**
 * 演示使用InputStreamReader 转换流解决中文乱码问题
 * 将字节流FileInputStream转成字符流InputStreamReader，指定编码gbk/utf-8
 */
public class InputStreamReader_ {
    public static void main(String[] args) {
        String filePath = "D:\\a.txt";
        InputStreamReader isr = null;
        try {
            //1.把FileInputStream转成InputStreamReader
            //2.指定编码gbk
            //isr = new InputStreamReader(new FileInputStream(filePath), "gbk");
            //3.把InputStreamReader传入BufferedReader
            //BufferedReader bufferedReader = new BufferedReader(isr);

            //将2和3合在一起
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(
                    new FileInputStream(filePath), "gbk"));
            //4.读取
            String data = bufferedReader.readLine();
            System.out.println("data=" + data);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (isr != null) {
                    isr.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

二、OutputStreamWriter的使用，具体代码如下：

/**
 * 演示OutputStreamWriter使用
 * 把FileOutputStream字节流，转成字符流OutputStreamWriter
 * 指定处理的编码gbk/utf-8/utf8
 */
public class OutputStreamWriter_ {
    public static void main(String[] args) {
        String filePath = "D:\\b.txt";
        OutputStreamWriter osw = null;
        try {
            osw = new OutputStreamWriter(new FileOutputStream(filePath), "utf8");
            osw.write("hello,筱路");
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (osw != null) {
                    osw.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

三、InputStreamReader 将一个字节的输入流转换为字符的输入流

@Test
    public void test1(){

        InputStreamReader isr = null;
        try {
            FileInputStream fis = new FileInputStream("学习记录.txt");
            isr = new InputStreamReader(fis); //使用系统默认的字符集
            //参数2：指明了字符集，具体使用哪个字符集，取决于 学习文件.txt 保存时 使用的字符集
            isr = new InputStreamReader(fis,"UTF-8");

            char[] cbuf = new char[10];
            int len;
            while ((len= isr.read(cbuf))!=-1){
                String str = new String(cbuf,0,len);
                System.out.println(str);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (isr!=null){
                try {
                    isr.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

四、将一个字符的输出流转换为一个字节的输出流

@Test
    public void test2() {
        InputStreamReader isr = null;
        OutputStreamWriter osw = null;
        try {
            //1.造文件、造流
            File file1 = new File("学习记录.txt");
            File file2 = new File("学习记录5.txt");

            FileInputStream fis = new FileInputStream(file1);
            FileOutputStream fos = new FileOutputStream(file2);

            isr = new InputStreamReader(fis,"UTF-8");
            osw = new OutputStreamWriter(fos,"GBK");
            //2.读取，写入过程
            int len;
            char[] cbuf = new char[5];
            while ((len= isr.read(cbuf))!=-1){
                osw.write(cbuf,0,len);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (isr!=null){
                try {
                    isr.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (osw!=null){
                try {
                    osw.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }