java_io字节流操作

看代码：

package wkl.file;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Writer;

import javax.imageio.stream.FileImageInputStream;

/**
 * 字节流的输入流和输出流基础是InputStream和OutputStream这两个抽象类，字节流的输入输出操作由这两个类的子类实现。
 * @author Administrator
 *
 */
public class InoutStreamTest {
    //字节流:向文中写入字符串
    public static void write22() throws Exception{
        File file = new File("G:\\xxx\\fd.txt");
        OutputStream out = new FileOutputStream(file);
        String string = "你好吗000990";
        byte[] b = string.getBytes();//把字符串转换成字节数组
        out.write(b);    //会把原来文件的内容先清除再写入，追加在后面讲
        /*for(int i=0;i<b.length;i++){
            out.write(b[i]);
        }*/
        out.close();
    } 

    //向文件中追加新内容
    public static void append() throws Exception{
        File file = new File("G:\\xxx\\fd.txt");
        OutputStream out = new FileOutputStream(file,true); //追加格式
        String str = "2015你好";
        byte[] b = str.getBytes();
        out.write(b);
        out.close();
    }

    //读文件的内容
    public static void reads() throws Exception{
        File file = new File("G:\\xxx\\fd.txt");
        InputStream in =new FileInputStream(file);
        int len =0;
        byte [] b = new byte[1024] ;
        while((len=in.read(b))!=-1){
            System.out.println(new String(b));//可以正常输出中文
        }
    }

    //字符流:写入数据
    public static void wri() throws Exception{
        File file = new File("G:\\xxx\\fd.txt");
        Writer writer = new FileWriter(file);
        String str = "我是字符流";
        writer.write(str);  //先清除原来的内容再写入新的内容
        writer.close();
    }

    public static void main(String args[]) throws Exception{
        //write22();
        //append();
        //reads();
        wri();
    }

}