Writer

Reader是带编码转换器的InputStream，它把byte转换为char，而Writer就是带编码转换器的OutputStream，它把char转换为byte并输出。from

FileWriter

try(Writer writer=new FileWriter("filename",charset);){
    writer.write(123);//写入char(123)
    writer.write("hello");//写入String
    writer.write("hello".toCharArray());//写入char[]
}

其它类型的Writer
CharArrayWriter,StringWriter

try(Writer writer =new CharArrayWriter();Writer writer2=new StringWriter();){
            writer.write(123);
            writer.write("22d");
            writer2.write(2);
            writer2.write("hello");
            System.out.println(writer2.toString());
        }

OutputStramWriter

try(Writer writer=new OutputWriter(new FileOutputStream("filename"),"utf-8"))