1.概念：序列化的意义是把一个实例对象进行即时冻结，保存即时数据；反序列化即是对冻结的数据进行解冻还原；或者可以说是数据格式的转化与复原。
2.需注意的几个问题：
1）：所有要序列化的对象必须实现Serializable，并且对
private static final long serialVersionUID = -2185617442774674835L;
虚拟机是否允许反序列化，不仅取决于类路径和功能代码是否一致，一个非常重要的一点是两个类的序列化 ID 是否一致
2）：transient和static修饰的字段默认都不会序列化，还有父类字段但父类没有实现Serializable的也不会序列化
3.对某些字段如果在传输过程中需要处理，则可重写writeObject和readObject
ATTENTION:writeObject and readObject must decorated by private
/**
* Created by dyf on 2019/5/22 9:35
* ATTENTION:writeObject and readObject must decorated by private
* 重写时，不处理的字段如果要序列化和反序列化也要put或read
* transient和static修饰的都不会序列化，或者父类字段但父类没有实现Serializable的也不会序列化
*/
public class Userimplements Serializable{
private static final long serialVersionUID = -6375006318163451630L;
private StringuserName;
private StringpassWord;
public User() {
}
public StringgetUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public StringgetPassWord() {
return passWord;
}
public void setPassWord(String passWord) {
this.passWord = passWord;
}
private void writeObject(ObjectOutputStream out){
try {
ObjectOutputStream.PutField putField = out.putFields();
System.out.println("原密码："+passWord);
passWord="encryption";
putField.put("passWord",passWord);
putField.put("userName",userName);
System.out.println("加密后的密码："+passWord);
out.writeFields();
}catch (IOException e) {
e.printStackTrace();
}
}
private void readObject(ObjectInputStream in)throws IOException, ClassNotFoundException {
ObjectInputStream.GetField getField = in.readFields();
Object password = getField.get("passWord", "");
Object username = getField.get("userName", "");
System.out.println("要解密的字符串："+password.toString());
passWord="pass";
userName=username.toString();
}
@Override
public StringtoString() {
return "User{" +
"userName='" +userName +'\'' +
", passWord='" +passWord +'\'' +
'}';
}
}
public class FieldsProcess {
public static void main(String[] args)throws IOException, ClassNotFoundException {
write();
read();
}
public static void write()throws IOException {
User user =new User();
user.setUserName("lining");
user.setPassWord("pass");
ObjectOutputStream objectOutputStream =new ObjectOutputStream(new FileOutputStream("d://test/4.obj"));
objectOutputStream.writeObject(user);
}
public static void read()throws IOException, ClassNotFoundException {
ObjectInputStream objectInputStream =new ObjectInputStream(new FileInputStream("d://test/4.obj"));
User user = (User) objectInputStream.readObject();
System.out.println(user.toString());
}
}
运行结果：
原密码：pass
加密后的密码：encryption
要解密的字符串：encryption
User{userName='lining', passWord='pass'}
4.多个对象写入和读取：
每次写入（同一个out对象write）都会清除上一次的文件内容，重新写入；一次可以写入多个对象，如果是不同类型的实例，读取时也要按顺序读取，否则报强转错误；如果读取的次数超过写入的次数，则报EOFEXCEPTION;注意：不同对象要按顺序，读写次数一致
