Java学习笔记39（转换流）

转换流：字符流和字节流之间的桥梁

用于处理程序的编码问题

OutputStreamWriter类：字符转字节流

写文本文件：

package demo;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;

public class Demo {
    public static void main(String[] args) throws IOException {
        writeGBK();
        writeUTF8();
    }

    public static void writeGBK() throws IOException {
        FileOutputStream fos = new FileOutputStream("d:\\gbk.txt");
        OutputStreamWriter osw = new OutputStreamWriter(fos, "GBK");
        osw.write("你好");// gbk的一个汉字是2个字节
        osw.close();
    }

    public static void writeUTF8() throws IOException {
        FileOutputStream fos = new FileOutputStream("d:\\utf8.txt");
        OutputStreamWriter osw = new OutputStreamWriter(fos, "UTF-8");
        osw.write("你好");// utf8的一个汉字是3个字节
        osw.close();
    }
}

InputStreamReader类：

字节转字符流过程：

这里读取上面写的文本文件：

package demo;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;

public class Demo {
    public static void main(String[] args) throws IOException {
        readGBK();
        readUTF8();
    }

    public static void readGBK() throws IOException {
        FileInputStream fis = new FileInputStream("d:\\gbk.txt");
        InputStreamReader isr = new InputStreamReader(fis);
        char[] ch = new char[1024];
        int len = isr.read(ch);
        System.out.println(new String(ch, 0, len));
    }

    public static void readUTF8() throws IOException {
        FileInputStream fis = new FileInputStream("d:\\utf8.txt");
        InputStreamReader isr = new InputStreamReader(fis, "UTF-8");
        char[] ch = new char[1024];
        int len = isr.read(ch);
        System.out.println(new String(ch, 0, len));
    }
}

这里注意，如果编码集和读取问文本不一致，就会发生乱码或者输出？的问题