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关键字transient与序列化
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‎README.md‎

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在这里，通过文章和代码，把这些知识点和技术的主要内容记录并汇总，供自己快速回顾，也分享给他人。
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## 关键字
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* [transient与序列化](src/cn/aofeng/demo/java/lang/TransientDemo.java)
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## 数据结构
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* [在控制台输出类似目录树的结构](src/cn/aofeng/demo/tree)
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‎src/cn/aofeng/demo/java/lang/serialization/Man.java‎

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package cn.aofeng.demo.java.lang.serialization;
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import java.io.Externalizable;
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import java.io.IOException;
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import java.io.ObjectInput;
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import java.io.ObjectOutput;
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/**
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* 自定义序列化和反序列化。
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*
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* @author <a href="mailto:[email protected]">聂勇</a>
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*/
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public class Man implements Externalizable {
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private String manName;
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private int manAge;
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private transient String password;
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public Man() {
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// nothing
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}
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public Man(String name, int age) {
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this.manName = name;
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this.manAge = age;
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}
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public Man(String name, int age, String password) {
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this.manName = name;
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this.manAge = age;
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this.password = password;
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}
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public String getManName() {
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return manName;
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}
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public void setManName(String manName) {
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this.manName = manName;
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}
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public int getManAge() {
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return manAge;
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}
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public void setManAge(int manAge) {
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this.manAge = manAge;
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}
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public String getPassword() {
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return password;
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}
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public void setPassword(String password) {
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this.password = password;
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}
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@Override
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public void writeExternal(ObjectOutput out) throws IOException {
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out.writeObject(manName);
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out.writeInt(manAge);
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out.writeObject(password);
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}
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@Override
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public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
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manName = (String) in.readObject();
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manAge = in.readInt();
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password = (String) in.readObject();
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}
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}

‎src/cn/aofeng/demo/java/lang/serialization/People.java‎

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package cn.aofeng.demo.java.lang.serialization;
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import java.io.Serializable;
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/**
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* 默认序列化和
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*
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* @author <a href="mailto:[email protected]">聂勇</a>
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*/
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public class People implements Serializable {
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private static final long serialVersionUID = 6235620243018494633L;
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private String name;
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private int age;
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private transient String address;
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private static String sTestNormal;
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private static transient String sTestTransient;
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public People(String name) {
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this.name = name;
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}
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public People(String name, int age) {
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this.name = name;
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this.age = age;
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}
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public People(String name, int age, String address) {
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this.name = name;
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this.age = age;
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this.address = address;
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}
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public String getName() {
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return name;
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}
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public void setName(String name) {
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this.name = name;
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}
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public int getAge() {
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return age;
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}
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public void setAge(int age) {
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this.age = age;
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}
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public String getAddress() {
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return address;
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}
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public void setAddress(String address) {
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this.address = address;
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}
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public String getsTestNormal() {
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return sTestNormal;
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}
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public void setsTestNormal(String sTestNormal) {
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People.sTestNormal = sTestNormal;
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}
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public String getsTestTransient() {
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return sTestTransient;
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}
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public void setsTestTransient(String sTestTransient) {
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People.sTestTransient = sTestTransient;
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}
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}

‎src/cn/aofeng/demo/java/lang/serialization/TransientDemo.java‎

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package cn.aofeng.demo.java.lang.serialization;
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import java.io.File;
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import java.io.FileInputStream;
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import java.io.FileOutputStream;
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import java.io.IOException;
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import java.io.ObjectInputStream;
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import java.io.ObjectOutputStream;
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import org.apache.commons.io.IOUtils;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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/**
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* 关键字 transient 测试。
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*
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* @author <a href="mailto:[email protected]">聂勇</a>
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*/
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public class TransientDemo {
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private static Logger _logger = LoggerFactory.getLogger(TransientDemo.class);
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private String _tempFileName = "TransientDemo";
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/**
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* 将对象序列化并保存到文件。
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*
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* @param obj 待序列化的对象
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*/
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public void save(Object obj) {
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ObjectOutputStream outs = null;
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try {
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outs = new ObjectOutputStream(
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new FileOutputStream( getTempFile(_tempFileName) ));
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outs.writeObject(obj);
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} catch (IOException e) {
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_logger.error("save object to file occurs error", e);
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} finally {
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IOUtils.closeQuietly(outs);
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}
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}
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/**
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* 从文件读取内容并反序列化成对象。
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*
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* @return {@link People}对象。如果读取文件出错 或 对象类型转换失败，返回null。
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*/
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public <T> T load() {
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ObjectInputStream ins = null;
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try {
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ins = new ObjectInputStream(
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new FileInputStream( getTempFile(_tempFileName)) );
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return ((T) ins.readObject());
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} catch (IOException e) {
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_logger.error("load object from file occurs error", e);
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} catch (ClassNotFoundException e) {
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_logger.error("load object from file occurs error", e);
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} finally {
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IOUtils.closeQuietly(ins);
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}
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return null;
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}
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private File getTempFile(String filename) {
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return new File(getTempDir(), filename);
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}
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private String getTempDir() {
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return System.getProperty("java.io.tmpdir");
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}
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private void displayPeople(People people) {
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if (null == people) {
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return;
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}
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String template = "People[name:%s, age:%d, address:%s, sTestNormal:%s, sTestTransient:%s]";
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System.out.println( String.format(template, people.getName(), people.getAge(),
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people.getAddress(), people.getsTestNormal(), people.getsTestTransient()));
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}
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private void displayMan(Man man) {
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if (null == man) {
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return;
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}
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String template = "Man[manName:%s, manAge:%d, password:%s]";
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System.out.println( String.format(template, man.getManName(), man.getManAge(), man.getPassword()) );
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}
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/**
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* @param args
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*/
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public static void main(String[] args) {
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System.out.println(">>> Serializable测试");
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TransientDemo demo = new TransientDemo();
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People people = new People("张三", 30, "中国广州");
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people.setsTestNormal("normal-first");
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people.setsTestTransient("transient-first");
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System.out.println("序列化之前的对象信息：");
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demo.displayPeople(people);
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demo.save(people);
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// 修改静态变量的值
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people.setsTestNormal("normal-second");
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people.setsTestTransient("transient-second");
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People fromLoad = demo.load();
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System.out.println("反序列化之后的对象信息：");
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demo.displayPeople(fromLoad);
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System.out.println("");
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System.out.println(">>> Externalizable测试");
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Man man = new Man("李四", 10, "假密码");
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System.out.println("序列化之前的对象信息：");
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demo.displayMan(man);
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demo.save(man);
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Man manFromLoadMan = demo.load();
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System.out.println("反序列化之后的对象信息：");
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demo.displayMan(manFromLoadMan);
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}
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}

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