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java的Serialization 机制
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基本使用方法 ??????? ??????? Serialization是指把類或者基本的數(shù)據(jù)類型持久化(persistence)到數(shù)據(jù)流(Stream)中,包括文件、字節(jié)流、網(wǎng)絡(luò)數(shù)據(jù)流。? ???????? JAVA中實(shí)現(xiàn)serialization主要靠?jī)蓚€(gè)類:ObjectOuputStream和ObjectInputStream。他們是JAVA IO系統(tǒng)里的OutputStream和InputStream的子類。既然他們是JAVA IO中的流,那么就可以像操作一般的流一樣來(lái)操作他們。下面是他們使用方法:?
Java代碼
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import ?java.io.ByteArrayInputStream;?? import ?java.io.ByteArrayOutputStream;?? import ?java.io.IOException;?? import ?java.io.ObjectInputStream;?? import ?java.io.ObjectOutputStream;?? import ?java.io.Serializable;?? ?? public ? class ?Pair? implements ?Serializable{?? ?? ????private ? static ? final ? long ?serialVersionUID?=?-1874850715617681161L;?? ????private ? int ?type;?? ????private ?String?name;?? ?????? ????public ? int ?getType()?{?? ????????return ?type;?? ????}?? ?? ????public ? void ?setType( int ?type)?{?? ????????this .type?=?type;?? ????}?? ?? ????public ?String?getName()?{?? ????????return ?name;?? ????}?? ?? ????public ? void ?setName(String?name)?{?? ????????this .name?=?name;?? ????}?? ?? ?????? ????public ?Pair( int ?type,?String?name)?{?? ????????super ();?? ????????this .type?=?type;?? ????????this .name?=?name;?? ????}?? ?? ????public ? static ? void ?main(String[]?args)? throws ?IOException,?ClassNotFoundException?{?? ?????????? ?????????? ????????ByteArrayOutputStream?bos?=?new ?ByteArrayOutputStream();?? ????????ObjectOutputStream?oos?=?new ?ObjectOutputStream(bos);?? ????????Pair?pair?=?new ?Pair( 1 ,? "charlie" );?? ????????oos.writeObject(pair);?? ?????????? ????????ByteArrayInputStream?bis?=?new ?ByteArrayInputStream(bos.toByteArray());?? ????????ObjectInputStream?ois?=?new ?ObjectInputStream(bis);?? ????????Pair?newpair?=?(Pair)?ois.readObject();?? ?????????? ????????System.out.println(newpair.getType()+":" +newpair.getName());?? ????}?? }?? 1. 這兩個(gè)類都是decorator模式的,在創(chuàng)建他們的時(shí)候,都要傳入一個(gè)基于字節(jié)的流,真正在底下存貯序列化數(shù)據(jù)的都是這些流。? 2. 被持久化的類要實(shí)現(xiàn)Serializable接口,這個(gè)接口沒(méi)有任何函數(shù),只是一個(gè)標(biāo)記接口。如果在一臺(tái)機(jī)器上進(jìn)行序列化,把得到的數(shù)據(jù)傳送到另外一個(gè)機(jī)器上進(jìn)行反序列化,那么這兩臺(tái)機(jī)器上的類應(yīng)該是完全一樣的,否則序列化是不會(huì)成功的。? 3. 切記不要把上面代碼中的bos用toString得到String,然后再?gòu)倪@個(gè)String中得到ByteArrayInputStream,再進(jìn)行反序列化。bos是以字節(jié)存貯的,轉(zhuǎn)成以字符存貯的String必然會(huì)造成數(shù)據(jù)的變化,而從String中到的byte[]也不會(huì)是之前那個(gè)byte[]了。我遇到過(guò)這個(gè)問(wèn)題,是因?yàn)槲蚁氚研蛄谢蟮臄?shù)據(jù)存在xml文件中。這個(gè)問(wèn)題的具體解決方法見(jiàn)我的另外一篇博客: http://zzy1943.iteye.com/blog/634553? java虛擬機(jī)在序列化和反序列化的時(shí)候都做了些什么? ? javadoc中對(duì)這兩個(gè)類的描述中對(duì)java的序列化機(jī)制進(jìn)行了詳細(xì)的描述:?
引用 The default serialization mechanism for an object writes the class of the object, the class signature, and the values of all non-transient and non-static fields. References to other objects (except in transient or static fields) cause those objects to be written also. Multiple references to a single object are encoded using a reference sharing mechanism so that graphs of objects can be restored to the same shape as when the original was written.
? 默認(rèn)的序列化機(jī)制寫(xiě)到流中的數(shù)據(jù)有:? 1、對(duì)象所屬的類? 2、類的簽名? 3、所有的非transient和非static的屬性? 4、對(duì)其他對(duì)象的引用也會(huì)造成對(duì)這些對(duì)象的序列化? 5、如果多個(gè)引用指向一個(gè)對(duì)象,那么會(huì)使用sharing reference機(jī)制?
引用 Classes that require special handling during the serialization and deserialization process must implement special methods with these exact signatures:
? Java代碼
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private ? void ?readObject(java.io.ObjectInputStream?stream)?? ????throws ?IOException,?ClassNotFoundException;?? private ? void ?writeObject(java.io.ObjectOutputStream?stream)?? ????throws ?IOException?? private ? void ?readObjectNoData()??? ????throws ?ObjectStreamException;??
轉(zhuǎn)載于:https://www.cnblogs.com/rosepotato/p/3404855.html
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