java学习-javabeans-persistence

/*
 * Copyright (c) 2020, guoxing, Co,. Ltd. All Rights Reserved
 */
package com.xingguo.java.beans.properties;

import java.beans.*;
import java.io.Serializable;

/**
 * Person
 *
 * @author guoxing
 * @date 2020/11/24 11:28 AM
 * @since
 */
public class Person implements Serializable {
    private String name;

    private int age;

    /**
     * javabeans - persistence
     * 首先要求实现 java.io.Serializable
     * 对于 不需要持久化的属性 要求 使用 "transient" 关键字保证其不会被持久化
     */
    // 设置当前Bean的属性变化支持工具
    // 强制属性更新
    private final transient PropertyChangeSupport propertyChangeSupport = new PropertyChangeSupport(this);
    // 勉强属性更新
    private final transient VetoableChangeSupport vetoableChangeSupport = new VetoableChangeSupport(this);

    public String getName() {
        return name;
    }


    /**
     * 当名称属性发生变化时,
     *
     * @param name
     */
    public void setName(String name) {
        String oldVal = this.name;
        String newVal = name;
        // 创建属性变更事件
        PropertyChangeEvent propertyChangeEvent = new PropertyChangeEvent(this, "name", oldVal, newVal);
        // 勉强属性
        fireVetoableChange(propertyChangeEvent);
        this.name = name;
        // 强迫事件变更机制
        // 强迫事件变更发生在 属性成功变更之后
        // 属性变更后发布事件
        // 发布事件
        propertyChangeSupport.firePropertyChange(propertyChangeEvent);
    }

    public void fireVetoableChange(PropertyChangeEvent event) {
        try {
            // 校验要求name 不能为纯粹的数字
            String propertyName = event.getPropertyName();
            if ("name".equals(propertyName) && isNumeric(String.valueOf(event.getNewValue()))) {
                throw new PropertyVetoException("name属性要求不能为纯数字", event);
            }
            vetoableChangeSupport.fireVetoableChange(event);
        } catch (PropertyVetoException propertyVetoException) {
            throw new RuntimeException(propertyVetoException);
        }

    }

    public void addVetoableChangeListener(VetoableChangeListener listener) {

    }

    public void removeVetoableChangeListener(VetoableChangeListener listener) {

    }


    public void addPropertyChangeListener(PropertyChangeListener listener) {
        propertyChangeSupport.addPropertyChangeListener(listener);
    }

    public void removePropertyChangeListener(PropertyChangeListener listener) {
        propertyChangeSupport.removePropertyChangeListener(listener);
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }

    public static boolean isNumeric(String str) {
        if (str == null) {
            return false;
        } else {
            int sz = str.length();

            for (int i = 0; i < sz; ++i) {
                if (!Character.isDigit(str.charAt(i))) {
                    return false;
                }
            }

            return true;
        }
    }
}

/*
 * Copyright (c) 2020, guoxing, Co,. Ltd. All Rights Reserved
 */
package com.xingguo.java.beans.persistence;

import com.xingguo.java.beans.properties.Person;
import lombok.extern.slf4j.Slf4j;
import org.springframework.util.StringUtils;

import java.io.*;
import java.nio.file.FileSystemNotFoundException;
import java.util.Properties;
import java.util.stream.Stream;

/**
 * PersonPersistence
 *
 * @author guoxing
 * @date 2020/11/24 10:34 PM
 * @since
 */
@Slf4j
public class PersonPersistence {
    public static void main(String[] args) throws IOException, ClassNotFoundException {
        Person person = new Person();
        person.setAge(18);
        person.setName("guoxing");
        // 获取当前编译路径
        // 需要获取到 启动命令中的 -classpath 中的 classes文件夹
        Properties properties = System.getProperties();
        String classpath = System.getProperty("java.class.path");
        String[] split = classpath.split(":");
        String currentCompilerClassPath = Stream.of(split)
                .filter(s -> StringUtils.endsWithIgnoreCase(s, "classes"))
                .map(File::new) // 转换为文件
                .filter(File::isDirectory)
                .filter(File::canRead)
                .filter(File::canWrite)
                .map(File::getAbsolutePath)
                .findFirst()
                .orElseThrow(FileSystemNotFoundException::new);
//        OutputStream outputStream = new FileOutputStream(new File(currentCompilerClassPath, "person.tmp"));
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        ObjectOutputStream objectOutputStream = new ObjectOutputStream(outputStream);
        objectOutputStream.writeObject(person);

        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(outputStream.toByteArray());
        ObjectInputStream objectInputStream = new ObjectInputStream(byteArrayInputStream);
        // 通过断点可以看出来 对于 未使用 "transient" 关键字的属性,通过流传递之后会得到相应的数据
        // 而对于使用了 "transient" 关键字的属性, 在转换之后就会变成其默认值
        Person newPerson = (Person) objectInputStream.readObject();
        log.info("{}", newPerson);
    }
}

persistence 重点在于 序列化传输后的数据是否存在

标签：java,name,import,javabeans,new,public,persistence,String
来源： https://www.cnblogs.com/xingguoblog/p/14033350.html