I/O 流

输入流的几个常用方法：

1，复制一个文件;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class copyDeno {

    public static void copy(String src, String dest) {//src 原文件，dest 待复制的文件
        //这儿需要加下判断src是否为文件和是否存在，
        InputStream in = null;
        OutputStream out = null;
        byte[] b = new byte[1024];
        int len;
        try {
            in = new FileInputStream(src);
            out = new FileOutputStream(dest);
            while ((len=in.read(b) )!= -1) {
                out.write(b,0,len);
            }

        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
            if (out != null) {
                try {
                    out.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }

    }
    public static void copyWithBuffer(String src, String dest) {//以上加入缓冲流
        InputStream in = null;
        OutputStream out = null;
        byte[] b = new byte[20];
        int len;
        try {
            in = new BufferedInputStream(new FileInputStream(src));
            out =new BufferedOutputStream(new FileOutputStream(dest));
            while ((len=in.read(b) )!= -1) {
                out.write(b,0,len);
            }
            //out.flush();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            Release.free(in, out);

        }
    }
    public static void main(String[] args) throws IOException {

        copy("F:\\Word\\eclipseword\\a4\\file\\a.txt", "F:\\Word\\eclipseword\\a4\\copyfile\\a1.txt");
        copyWithBuffer("F:\\Word\\eclipseword\\a4\\file\\b.txt", "F:\\Word\\eclipseword\\a4\\copyfile\\b1.txt");

    }
}

封装一个关闭流(释放资源)方法：

package IO;

import java.io.Closeable;
import java.io.IOException;
public class Release {
 public static void free(Closeable...stream){
	 for(Closeable st:stream){
		 if(st != null){
			 try {
				st.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		 }
	 }

 }
}

　　2,复制一个文件夹的所有内容到另外一个文件夹中

package IOfuxi;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

import IO.Release;

/*复制多级文件夹
* A:封装数据源File
* B:封装目的地File
* C:判断该File是文件夹还是文件
* a:是文件夹
* 就在目的地目录下创建该文件夹
* 获取该File对象下的所有文件或者文件夹File对象
* 遍历得到每一个File对象
* 回到C
* b:是文件
* 就复制(字节流)
* */
public class CopyFolderduo {

public static void main(String[] args) throws IOException {
copyfolder("F:\\Word\\eclipseword\\a4\\file",
"D:\\Java视频\\day21\\day21");

}

private static void copyfolder(String src,String des) throws IOException{
File file=new File(src);
File newfile=new File(des);
//判断文件是否存在
if(!file.exists()||!newfile.exists()){
return;
}else{
fuzhi(file,newfile);
}

}

private static void fuzhi(File file, File newfile) throws IOException {

// 判断该File是文件夹还是文件
if(file.isDirectory()){
File newFloder=new File(newfile,file.getName());
//创建目标路径文件夹
newFloder.mkdir();
//// 获取该File对象下的所有文件或者文件夹File对象
File[] arrfile=file.listFiles();
for(File f:arrfile){
//递归调用
fuzhi(f,newFloder);
}

}else{
File newf=new File(newfile,file.getName());
copyfile(file,newf);

}

}

//复制文件的方法
private static void copyfile(File file, File newf) throws IOException {
BufferedInputStream in= new BufferedInputStream(new FileInputStream(file));
BufferedOutputStream out=new BufferedOutputStream(new FileOutputStream(newf));
byte[] arr=new byte[1024];
int len;
while((len=in.read(arr))!=-1){
out.write(arr, 0, len);
out.flush();
}
// out.flush();
Release.free(in,out);
}

}

3.压缩一个文件夹

 package zy823;

 import java.io.BufferedInputStream;
 import java.io.BufferedOutputStream;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.InputStream;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipOutputStream;

 public class zipFolder {
      public static void zipFile(String src,String dest){
             ZipOutputStream zos = null;
             try {
                 zos = new ZipOutputStream(new BufferedOutputStream(new FileOutputStream(dest)));//
                 File fileSrc = new File(src);
               if(!fileSrc.exists()){
                throw new FileNotFoundException();
               }else{
                 zip(fileSrc.getName(),zos,fileSrc);
                   zos.flush();
                   zos.close();
               }
             } catch (FileNotFoundException e1) {
             // TODO Auto-generated catch block
               e1.printStackTrace();
             }catch (Exception e) {
               // TODO Auto-generated catch block
              e.printStackTrace();
             }

           }
           private static void zip(String dest,ZipOutputStream zos,File src)throws Exception{
             byte[] b = new byte[1024];
             InputStream is = null;
             if(src.isFile()){
                 zos.putNextEntry(new ZipEntry(dest));
               is = new BufferedInputStream(new FileInputStream(src));
               int len;
               while((len = is.read(b)) != -1){
                 zos.write(b, 0, len);
               }
               zos.flush();
               is.close();
               zos.closeEntry();
             }else{
                  File[] files = src.listFiles();
                zos.putNextEntry(new ZipEntry(dest+"/"));
                for(File temp:files){
                  zip(dest+"/"+temp.getName(),zos,temp);
                }
             }
           }

 }