IO学习

1.输入输出流

io流.PNG

1.代码:

package Test;

import org.junit.Test;

import java.io.*;

public class JavaIO {
    /*
     * 字节型输入流
     * */
    @Test
  public void fileinputstream(){
      File file=new File("D:/test/aaa.txt");
      System.out.println(file.isFile());
      FileInputStream fis=null;
      try {
          fis=new FileInputStream(file);
          byte[] bit= new byte[5];
          int code=fis.read(bit);
          while (code!=-1){
              String value=new String(bit,0,code);
              System.out.print(value);
              code=fis.read(bit);
          }
      } catch (IOException e) {
          e.printStackTrace();
      }finally {
          try {
              if(fis!=null) {//这个判断是问了防止file找不到文件报错导致FileinputStream没有创建然后空指针
                  fis.close();//关闭通道
              }
          }catch (IOException e){
              e.printStackTrace();
          }
      }
  }
    /**
     * 字符型输出流
     */
  @Test
 public void fileoutputstream(){
      File file=new File("D:/test/bbb.txt");
      FileOutputStream outputStream=null;
      try {
          outputStream=new FileOutputStream(file,true);
//          byte[] bytes=new byte[5];
//          bytes[0]=97;
          String str="a+b+c";
          byte[] bytes=str.getBytes();
          outputStream.write(bytes);
          outputStream.flush();
      } catch (IOException e) {
          e.printStackTrace();
      }finally {
          try {
              outputStream.close();
          }catch (IOException e){
              e.printStackTrace();
          }
      }
  }
  /*
  * 文件的复制,bug没有判断是否是文件还是文件夹
  * */
  public void fileCopy(String fileName,String copyPath){
       File file=new File(fileName);
      FileInputStream fis=null;
      FileOutputStream fot=null;
      try {
          fis=new FileInputStream(file);
          byte[] bit= new byte[1024];
          int code=fis.read(bit);
          while (code!=-1){
              fot=new FileOutputStream(copyPath,true);
              //String value=new String(bit,0,code);
              fot.write(bit,0,code);
              code=fis.read(bit);
          }
      } catch (IOException e) {
          e.printStackTrace();
      }finally {
          try {
              if(fis!=null) {//这个判断是问了防止file找不到文件报错导致FileinputStream没有创建然后空指针
                  fis.close();//关闭通道
                  fot.close();
              }
          }catch (IOException e){
              e.printStackTrace();
          }
      }
  }
  @Test
  public void copyTest(){
     // this.fileCopy("D:/test/bbb.txt","D:/test/ccc.txt");
      File file =new File("D:\\test");
      JavaIO javaIO=new JavaIO();
      javaIO.superCopy(file,"D:\\test");
      //this.superCopy(file,"D:/test1");
  }
  public void superCopy(File file,String newPath){
     File[] files=file.listFiles();
     String oldPath=file.getAbsolutePath();
     String newFilePath=newPath+oldPath.split(":")[1];
     File newFile=new File(newFilePath);
     if(files!=null){
         //file是文件夹
          newFile.mkdir();
         System.out.println(newFilePath+"文件夹创建");
         if(files!=null&&files.length!=0){
             for (File f:files) {
                 this.superCopy(f,newPath);
             }
         }
     }else {
         //file是文件
         FileInputStream fis=null;
         FileOutputStream fot=null;
         try {
             fis=new FileInputStream(file);
             fot=new FileOutputStream(newFile);
             byte[] bit= new byte[1024];
             int code=fis.read(bit);
             while (code!=-1){
                 //String value=new String(bit,0,code);
                 fot.write(bit,0,code);
                 fot.flush();
                 code=fis.read(bit);
             }
         } catch (IOException e) {
             e.printStackTrace();
         }finally {
             try {
                 if(fis!=null) {//这个判断是问了防止file找不到文件报错导致FileinputStream没有创建然后空指针
                     fis.close();//关闭通道
                     fot.close();
                 }
             }catch (IOException e){
                 e.printStackTrace();
             }
         }
     }
  }
  /*
  * 对象流,使用前需要将对象序列化
  * */
  @Test
  public void objeceInputStream()throws Exception{
    //将对象直接记录在文件中
//      Person p=new Person("长啥","10010",12);
//      FileOutputStream fos=new FileOutputStream("D:/test/ddd.txt");
//      ObjectOutputStream obs=new ObjectOutputStream(fos);
//      obs.writeObject(p);
//      obs.flush();
//      obs.close();
      FileInputStream ins=new FileInputStream("D:/test/ddd.txt");
      ObjectInputStream ons=new ObjectInputStream(ins);
      Person person=(Person) ons.readObject();
      System.out.println(person.getName());
      person.eat();
  }
}

2.总结

io总结.PNG