做课程设计,卡在这里卡了一天,太难了,经过无数的百度,博客等等等等,还好是解决了,总结一下
注意: 当我们使用对象流的时候,我们向文件中写入或者是读出都是用的序列化对象,而序列化对象在写入文件时,系统会自动添加aced 0005的一个头部,并且占4个字节,这个我在网上看到的,经过验证确实如此。
解决: 我们只需要在写入文件的时候判断该文件是否已经存在,或者说是否已经写入过对象了,如果写入过对象,我们把前面那个4个字节去掉在写入到文件里就OK了
上代码(Recording是一个序列化的类,自己随便弄个类验证即可)
import java.io.*;
public class test {
public static void main(String args[]){
File file = new File("text.txt");
Recording r[] = new Recording[10];
boolean isexist=false;//定义一个用来判断文件是否需要截掉头aced 0005的
try{
if(file.exists()){ //文件是否存在
isexist=true;
FileOutputStream fo=new FileOutputStream(file,true);
ObjectOutputStream oos = new ObjectOutputStream(fo);
long pos=0;
if(isexist){
pos=fo.getChannel().position()-4;//追加的时候去掉头部aced 0005
fo.getChannel().truncate(pos);
}
oos.writeObject(new Recording("小明","锡纸烫",388,"李四","10.23"));//进行序列化
oos.close();
}
else{//文件不存在
file.createNewFile();
FileOutputStream fo=new FileOutputStream(file);
ObjectOutputStream wr1 = new ObjectOutputStream(fo);
wr1.writeObject(new Recording("小花","纹理烫",288,"张三","10.23"));
wr1.writeObject(new Recording("小明","锡纸烫",388,"李四","10.23"));
wr1.writeObject(new Recording("小刚","洗发",18,"张三","10.23"));
wr1.writeObject(new Recording("小强","洗发",18,"张三","10.23"));
wr1.writeObject(new Recording("小明","洗发",18,"张三","10.23"));
wr1.close(); // 写入操作完成
}
FileInputStream in = new FileInputStream(file);
ObjectInputStream re = new ObjectInputStream(in);
Recording test = null;
while((test = (Recording)re.readObject()) != null){
System.out.println(test.name);
}
re.close();
}
catch(IOException e){}
catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
}