java transient关键字

当序列化实现Serializable这个接口时，transient修饰属性，用来表示不进行序列化。

举例：

实体类：

package com.xhx.java.javatransient.entity;


import java.io.Serializable;

public class User implements Serializable {

    private String name;
    private String gender;

    private transient String password;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                ", gender='" + gender + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

把上面实体类写入文件中：

package com.xhx.java.javatransient;


import com.xhx.java.javatransient.entity.User;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

public class JavaTransientApplication {

    public static void main(String[] args) throws Exception {
        User user = new User();
        user.setName("xu");
        user.setGender("man");
        user.setPassword("abcdefg");
        String path = "/media/xuhaixing/java/myDocument/java/java-transient/src/main/java/aa.txt";
        ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream(path));
        objectOutputStream.writeObject(user);
        objectOutputStream.close();

        ObjectInputStream objectInputStream = new ObjectInputStream(new FileInputStream(path));
        Object o = objectInputStream.readObject();
        objectInputStream.close();

        System.out.println(o);
        //transient 修饰后不可被通过Serializable接口的序列化
        //输出结果
        //User{name='xu', gender='man', password='null'}

    }
}

如果实体类不实现Serializable会报下面错误：

Exception in thread "main" java.io.NotSerializableException: com.xhx.java.javatransient.entity.User
  at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1184)
  at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
  at com.xhx.java.javatransient.JavaTransientApplication.main(JavaTransientApplication.java:20)
Disconnected from the target VM, address: '127.0.0.1:33093', transport: 'socket'

执行结果输出如下：

User{name='xu', gender='man', password='null'}

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