java_IO_2

1.字节流  InputStream（抽象类）

 package ioStudy;

 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;

 /*
 1.创建源
 2.选择流
 3.操作
 4.释放资源
 */
 public class IOstudy2 {
     public static void main(String[] args) {
         File file = new File("test.txt");    //创建源

         InputStream is = null;

         try {
             is = new FileInputStream(file);     //  选择流
             int temp;
             while ((temp = is.read()) != -1) {      //一次读一个字节  如果包含中文可能会出现乱码  考虑使用字符流
                 System.out.print((char) temp);    //操作
             }
         } catch (FileNotFoundException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         } catch (IOException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }finally {
             if(is!=null) {
                 try {
                     is.close();        //释放资源
                 } catch (IOException e) {
                     // TODO Auto-generated catch block
                     e.printStackTrace();
                 }
             }
         }
     }
 }

 package ioStudy;

 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;

 /*
 1.创建源
 2.选择流
 3.操作
 4.释放资源
 */
 public class IOstudy3 {
     public static void main(String[] args) {
         File file = new File("test.txt");
         InputStream is = null;
         try {
             is = new FileInputStream(file);
             byte[] buffer = new byte[5];
             int len;
             while ((len = is.read(buffer)) != -1) {    //一次读取多个
                 String s = new String(buffer,0,len);
                 System.out.print(s);
             }
         } catch (FileNotFoundException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         } catch (IOException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }finally {
             if(is!=null) {
                 try {
                     is.close();
                 } catch (IOException e) {
                     // TODO Auto-generated catch block
                     e.printStackTrace();
                 }
             }
         }
     }
 }

---

2.OutputStream

 package ioStudy;

 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;

 /*
 1.创建源
 2.选择流
 3.操作
 4.释放资源
 */
 public class IOstudy4 {
     public static void main(String[] args) {
         File file = new File("output.txt"); // 不存在会自动创建
         OutputStream os = null;

         try {
             os = new FileOutputStream(file,true);  //开启向后追加  不然每次都删掉原来的 再写  默认的是false
             String temp = "hello world!\r\n";
             byte[] b = temp.getBytes();
             os.write(b, 0, b.length);
             os.flush();   //刷新内存
         } catch (FileNotFoundException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         } catch (IOException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         } finally {
             if (os != null) {
                 try {
                     os.close();
                 } catch (IOException e) {
                     // TODO Auto-generated catch block
                     e.printStackTrace();
                 }
             }
         }
     }
 }

3.实现文件的copy

 package ioStudy;

 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;

 /*
 1.创建源
 2.选择流
 3.操作
 4.释放资源
 */
 public class Copy {
     public static void main(String[] args) {
         copy("test.txt","testcopy.txt");
     }

     public static void copy(String source, String destination) {
         File src = new File(source);
         File dest = new File(destination);
         InputStream is = null;
         OutputStream os = null;
         try {
             is = new FileInputStream(src);
             os = new FileOutputStream(dest);

             byte[] buffer = new byte[1034];
             int len;
             while ((len = is.read(buffer)) != -1) {
                 os.write(buffer, 0, len);
                 os.flush();
             }
         } catch (FileNotFoundException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         } catch (IOException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         } finally {
             // 流关闭的原则 先打开的后关闭
             if (os != null) {
                 try {
                     os.close();
                 } catch (IOException e) {
                     // TODO Auto-generated catch block
                     e.printStackTrace();
                 }
             }

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