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在java中要想實(shí)現(xiàn)多線程，有兩種手段，一種是繼續(xù)Thread類，另外一種是實(shí)現(xiàn)Runable接口。

對(duì)于直接繼承Thread的類來說，代碼大致框架是：

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class?類名?extends?Thread{ 方法1; 方法2； … public?void?run(){ // other code… } 屬性1； 屬性2； … }

先看一個(gè)簡(jiǎn)單的例子：

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/** ?* @author Rollen-Holt 繼承Thread類,直接調(diào)用run方法 ?* */ class?hello?extends?Thread { ????public?hello() { ????} ????public?hello(String name) { ????????this.name = name; ????} ????public?void?run() { ????????for?(int?i =?0; i <?5; i++) { ????????????System.out.println(name +?"運(yùn)行???? "?+ i); ????????} ????} ????public?static?void?main(String[] args) { ????????hello h1=new?hello("A"); ????????hello h2=new?hello("B"); ????????h1.run(); ????????h2.run(); ????} ????private?String name; }

【運(yùn)行結(jié)果】：

A運(yùn)行???? 0

A運(yùn)行???? 1

A運(yùn)行???? 2

A運(yùn)行???? 3

A運(yùn)行???? 4

B運(yùn)行???? 0

B運(yùn)行???? 1

B運(yùn)行???? 2

B運(yùn)行???? 3

B運(yùn)行???? 4

我們會(huì)發(fā)現(xiàn)這些都是順序執(zhí)行的，說明我們的調(diào)用方法不對(duì)，應(yīng)該調(diào)用的是start（）方法。

當(dāng)我們把上面的主函數(shù)修改為如下所示的時(shí)候：

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public?static?void?main(String[] args) { ????????hello h1=new?hello("A"); ????????hello h2=new?hello("B"); ????????h1.start(); ????????h2.start(); ????}

然后運(yùn)行程序，輸出的可能的結(jié)果如下：

A運(yùn)行???? 0

B運(yùn)行???? 0

B運(yùn)行???? 1

B運(yùn)行???? 2

B運(yùn)行???? 3

B運(yùn)行???? 4

A運(yùn)行???? 1

A運(yùn)行???? 2

A運(yùn)行???? 3

A運(yùn)行???? 4

因?yàn)樾枰玫紺PU的資源，所以每次的運(yùn)行結(jié)果基本是都不一樣的，呵呵。

注意：雖然我們?cè)谶@里調(diào)用的是start（）方法，但是實(shí)際上調(diào)用的還是run（）方法的主體。

那么：為什么我們不能直接調(diào)用run（）方法呢？

我的理解是：線程的運(yùn)行需要本地操作系統(tǒng)的支持。

如果你查看start的源代碼的時(shí)候，會(huì)發(fā)現(xiàn)：

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public?synchronized?void?start() { ????????/** ?????* This method is not invoked for the main method thread or "system" ?????* group threads created/set up by the VM. Any new functionality added ?????* to this method in the future may have to also be added to the VM. ?????* ?????* A zero status value corresponds to state "NEW". ?????????*/ ????????if?(threadStatus !=?0?||?this?!= me) ????????????throw?new?IllegalThreadStateException(); ????????group.add(this); ????????start0(); ????????if?(stopBeforeStart) { ????????stop0(throwableFromStop); ????} } private?native?void?start0();

注意我用紅色加粗的那一條語句，說明此處調(diào)用的是start0（）。并且這個(gè)這個(gè)方法用了native關(guān)鍵字，次關(guān)鍵字表示調(diào)用本地操作系統(tǒng)的函數(shù)。因?yàn)槎嗑€程的實(shí)現(xiàn)需要本地操作系統(tǒng)的支持。

但是start方法重復(fù)調(diào)用的話，會(huì)出現(xiàn)java.lang.IllegalThreadStateException異常。

通過實(shí)現(xiàn)Runnable接口：

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大致框架是：

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class?類名?implements?Runnable{ 方法1; 方法2； … public?void?run(){ // other code… } 屬性1； 屬性2； … }

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來先看一個(gè)小例子吧：

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/** ?* @author Rollen-Holt 實(shí)現(xiàn)Runnable接口 ?* */ class?hello?implements?Runnable { ????public?hello() { ????} ????public?hello(String name) { ????????this.name = name; ????} ????public?void?run() { ????????for?(int?i =?0; i <?5; i++) { ????????????System.out.println(name +?"運(yùn)行???? "?+ i); ????????} ????} ????public?static?void?main(String[] args) { ????????hello h1=new?hello("線程A"); ????????Thread demo=?new?Thread(h1); ????????hello h2=new?hello("線程Ｂ"); ????????Thread demo1=new?Thread(h2); ????????demo.start(); ????????demo1.start(); ????} ????private?String name; }

【可能的運(yùn)行結(jié)果】：

線程A運(yùn)行???? 0

線程Ｂ運(yùn)行???? 0

線程Ｂ運(yùn)行???? 1

線程Ｂ運(yùn)行???? 2

線程Ｂ運(yùn)行???? 3

線程Ｂ運(yùn)行???? 4

線程A運(yùn)行???? 1

線程A運(yùn)行???? 2

線程A運(yùn)行???? 3

線程A運(yùn)行???? 4

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關(guān)于選擇繼承Thread還是實(shí)現(xiàn)Runnable接口？

其實(shí)Thread也是實(shí)現(xiàn)Runnable接口的：

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class?Thread?implements?Runnable { ????//… public?void?run() { ????????if?(target !=?null) { ?????????????target.run(); ????????} ????????} }

其實(shí)Thread中的run方法調(diào)用的是Runnable接口的run方法。不知道大家發(fā)現(xiàn)沒有，Thread和Runnable都實(shí)現(xiàn)了run方法，這種操作模式其實(shí)就是代理模式。關(guān)于代理模式，我曾經(jīng)寫過一個(gè)小例子呵呵，大家有興趣的話可以看一下：http://www.cnblogs.com/rollenholt/archive/2011/08/18/2144847.html

Thread和Runnable的區(qū)別：

如果一個(gè)類繼承Thread，則不適合資源共享。但是如果實(shí)現(xiàn)了Runable接口的話，則很容易的實(shí)現(xiàn)資源共享。

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/** ?* @author Rollen-Holt 繼承Thread類，不能資源共享 ?* */ class?hello?extends?Thread { ????public?void?run() { ????????for?(int?i =?0; i <?7; i++) { ????????????if?(count >?0) { ????????????????System.out.println("count= "?+ count--); ????????????} ????????} ????} ????public?static?void?main(String[] args) { ????????hello h1 =?new?hello(); ????????hello h2 =?new?hello(); ????????hello h3 =?new?hello(); ????????h1.start(); ????????h2.start(); ????????h3.start(); ????} ????private?int?count =?5; }

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【運(yùn)行結(jié)果】：

count= 5

count= 4

count= 3

count= 2

count= 1

count= 5

count= 4

count= 3

count= 2

count= 1

count= 5

count= 4

count= 3

count= 2

count= 1

大家可以想象，如果這個(gè)是一個(gè)買票系統(tǒng)的話，如果count表示的是車票的數(shù)量的話，說明并沒有實(shí)現(xiàn)資源的共享。

我們換為Runnable接口

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class?MyThread?implements?Runnable{ ????private?int?ticket =?5;??//5張票 ????public?void?run() { ????????for?(int?i=0; i<=20; i++) { ????????????if?(this.ticket >?0) { ????????????????System.out.println(Thread.currentThread().getName()+?"正在賣票"+this.ticket--); ????????????} ????????} ????} } public?class?lzwCode { ????? ????public?static?void?main(String [] args) { ????????MyThread my =?new?MyThread(); ????????new?Thread(my,?"1號(hào)窗口").start(); ????????new?Thread(my,?"2號(hào)窗口").start(); ????????new?Thread(my,?"3號(hào)窗口").start(); ????} }

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【運(yùn)行結(jié)果】：

count= 5

count= 4

count= 3

count= 2

count= 1

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總結(jié)一下吧：

實(shí)現(xiàn)Runnable接口比繼承Thread類所具有的優(yōu)勢(shì)：

1）：適合多個(gè)相同的程序代碼的線程去處理同一個(gè)資源

2）：可以避免java中的單繼承的限制

3）：增加程序的健壯性，代碼可以被多個(gè)線程共享，代碼和數(shù)據(jù)獨(dú)立。

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所以，本人建議大家勁量實(shí)現(xiàn)接口。

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/** ?* @author Rollen-Holt ?* 取得線程的名稱 ?* */ class?hello?implements?Runnable { ????public?void?run() { ????????for?(int?i =?0; i <?3; i++) { ????????????System.out.println(Thread.currentThread().getName()); ????????} ????} ????public?static?void?main(String[] args) { ????????hello he =?new?hello(); ????????new?Thread(he,"A").start(); ????????new?Thread(he,"B").start(); ????????new?Thread(he).start(); ????} }

【運(yùn)行結(jié)果】：

A

A

A

B

B

B

Thread-0

Thread-0

Thread-0

說明如果我們沒有指定名字的話，系統(tǒng)自動(dòng)提供名字。

提醒一下大家：main方法其實(shí)也是一個(gè)線程。在java中所以的線程都是同時(shí)啟動(dòng)的，至于什么時(shí)候，哪個(gè)先執(zhí)行，完全看誰先得到CPU的資源。

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在java中，每次程序運(yùn)行至少啟動(dòng)2個(gè)線程。一個(gè)是main線程，一個(gè)是垃圾收集線程。因?yàn)槊慨?dāng)使用java命令執(zhí)行一個(gè)類的時(shí)候，實(shí)際上都會(huì)啟動(dòng)一個(gè)ＪＶＭ，每一個(gè)ｊＶＭ實(shí)習(xí)在就是在操作系統(tǒng)中啟動(dòng)了一個(gè)進(jìn)程。

判斷線程是否啟動(dòng)

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/** ?* @author Rollen-Holt 判斷線程是否啟動(dòng) ?* */ class?hello?implements?Runnable { ????public?void?run() { ????????for?(int?i =?0; i <?3; i++) { ????????????System.out.println(Thread.currentThread().getName()); ????????} ????} ????public?static?void?main(String[] args) { ????????hello he =?new?hello(); ????????Thread demo =?new?Thread(he); ????????System.out.println("線程啟動(dòng)之前---》"?+ demo.isAlive()); ????????demo.start(); ????????System.out.println("線程啟動(dòng)之后---》"?+ demo.isAlive()); ????} }

【運(yùn)行結(jié)果】

線程啟動(dòng)之前---》false

線程啟動(dòng)之后---》true

Thread-0

Thread-0

Thread-0

主線程也有可能在子線程結(jié)束之前結(jié)束。并且子線程不受影響，不會(huì)因?yàn)橹骶€程的結(jié)束而結(jié)束。

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線程的強(qiáng)制執(zhí)行：

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/** ?????* @author Rollen-Holt 線程的強(qiáng)制執(zhí)行 ?????* */ ????class?hello?implements?Runnable { ????????public?void?run() { ????????????for?(int?i =?0; i <?3; i++) { ????????????????System.out.println(Thread.currentThread().getName()); ????????????} ????????} ????? ????????public?static?void?main(String[] args) { ????????????hello he =?new?hello(); ????????????Thread demo =?new?Thread(he,"線程"); ????????????demo.start(); ????????????for(int?i=0;i<50;++i){ ????????????????if(i>10){ ????????????????????try{ ????????????????????????demo.join();??//強(qiáng)制執(zhí)行demo ????????????????????}catch?(Exception e) { ????????????????????????e.printStackTrace(); ????????????????????} ????????????????} ????????????????System.out.println("main 線程執(zhí)行-->"+i); ????????????} ????????} ????}

【運(yùn)行的結(jié)果】：

main?線程執(zhí)行-->0

main?線程執(zhí)行-->1

main?線程執(zhí)行-->2

main?線程執(zhí)行-->3

main?線程執(zhí)行-->4

main?線程執(zhí)行-->5

main?線程執(zhí)行-->6

main?線程執(zhí)行-->7

main?線程執(zhí)行-->8

main?線程執(zhí)行-->9

main?線程執(zhí)行-->10

線程

線程

線程

main?線程執(zhí)行-->11

main?線程執(zhí)行-->12

main?線程執(zhí)行-->13

．．．

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線程的休眠：

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/** ?* @author Rollen-Holt 線程的休眠 ?* */ class?hello?implements?Runnable { ????public?void?run() { ????????for?(int?i =?0; i <?3; i++) { ????????????try?{ ????????????????Thread.sleep(2000); ????????????}?catch?(Exception e) { ????????????????e.printStackTrace(); ????????????} ????????????System.out.println(Thread.currentThread().getName() + i); ????????} ????} ????public?static?void?main(String[] args) { ????????hello he =?new?hello(); ????????Thread demo =?new?Thread(he,?"線程"); ????????demo.start(); ????} }

【運(yùn)行結(jié)果】：（結(jié)果每隔2s輸出一個(gè)）

線程0

線程1

線程2

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線程的中斷：

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/** ?* @author Rollen-Holt 線程的中斷 ?* */ class?hello?implements?Runnable { ????public?void?run() { ????????System.out.println("執(zhí)行run方法"); ????????try?{ ????????????Thread.sleep(10000); ????????????System.out.println("線程完成休眠"); ????????}?catch?(Exception e) { ????????????System.out.println("休眠被打斷"); ????????????return;??//返回到程序的調(diào)用處 ????????} ????????System.out.println("線程正常終止"); ????} ????public?static?void?main(String[] args) { ????????hello he =?new?hello(); ????????Thread demo =?new?Thread(he,?"線程"); ????????demo.start(); ????????try{ ????????????Thread.sleep(2000); ????????}catch?(Exception e) { ????????????e.printStackTrace(); ????????} ????????demo.interrupt();?//2s后中斷線程 ????} }

【運(yùn)行結(jié)果】：

執(zhí)行run方法

休眠被打斷

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在java程序中，只要前臺(tái)有一個(gè)線程在運(yùn)行，整個(gè)java程序進(jìn)程不會(huì)小時(shí)，所以此時(shí)可以設(shè)置一個(gè)后臺(tái)線程，這樣即使java進(jìn)程小時(shí)了，此后臺(tái)線程依然能夠繼續(xù)運(yùn)行。

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/** ?* @author Rollen-Holt 后臺(tái)線程 ?* */ class?hello?implements?Runnable { ????public?void?run() { ????????while?(true) { ????????????System.out.println(Thread.currentThread().getName() +?"在運(yùn)行"); ????????} ????} ????public?static?void?main(String[] args) { ????????hello he =?new?hello(); ????????Thread demo =?new?Thread(he,?"線程"); ????????demo.setDaemon(true); ????????demo.start(); ????} }

雖然有一個(gè)死循環(huán)，但是程序還是可以執(zhí)行完的。因?yàn)樵谒姥h(huán)中的線程操作已經(jīng)設(shè)置為后臺(tái)運(yùn)行了。

線程的優(yōu)先級(jí)：

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/** ?* @author Rollen-Holt 線程的優(yōu)先級(jí) ?* */ class?hello?implements?Runnable { ????public?void?run() { ????????for(int?i=0;i<5;++i){ ????????????System.out.println(Thread.currentThread().getName()+"運(yùn)行"+i); ????????} ????} ????public?static?void?main(String[] args) { ????????Thread h1=new?Thread(new?hello(),"A"); ????????Thread h2=new?Thread(new?hello(),"B"); ????????Thread h3=new?Thread(new?hello(),"C"); ????????h1.setPriority(8); ????????h2.setPriority(2); ????????h3.setPriority(6); ????????h1.start(); ????????h2.start(); ????????h3.start(); ????????? ????} }

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【運(yùn)行結(jié)果】：

A運(yùn)行0

A運(yùn)行1

A運(yùn)行2

A運(yùn)行3

A運(yùn)行4

B運(yùn)行0

C運(yùn)行0

C運(yùn)行1

C運(yùn)行2

C運(yùn)行3

C運(yùn)行4

B運(yùn)行1

B運(yùn)行2

B運(yùn)行3

B運(yùn)行4

。但是請(qǐng)讀者不要誤以為優(yōu)先級(jí)越高就先執(zhí)行。誰先執(zhí)行還是取決于誰先去的CPU的資源、

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另外，主線程的優(yōu)先級(jí)是5.

線程的禮讓。

在線程操作中，也可以使用yield（）方法，將一個(gè)線程的操作暫時(shí)交給其他線程執(zhí)行。

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/** ?* @author Rollen-Holt 線程的優(yōu)先級(jí) ?* */ class?hello?implements?Runnable { ????public?void?run() { ????????for(int?i=0;i<5;++i){ ????????????System.out.println(Thread.currentThread().getName()+"運(yùn)行"+i); ????????????if(i==3){ ????????????????System.out.println("線程的禮讓"); ????????????????Thread.currentThread().yield(); ????????????} ????????} ????} ????public?static?void?main(String[] args) { ????????Thread h1=new?Thread(new?hello(),"A"); ????????Thread h2=new?Thread(new?hello(),"B"); ????????h1.start(); ????????h2.start(); ????????? ????} }

A運(yùn)行0

A運(yùn)行1

A運(yùn)行2

A運(yùn)行3

線程的禮讓

A運(yùn)行4

B運(yùn)行0

B運(yùn)行1

B運(yùn)行2

B運(yùn)行3

線程的禮讓

B運(yùn)行4

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同步和死鎖：

【問題引出】:比如說對(duì)于買票系統(tǒng)，有下面的代碼：

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/** ?* @author Rollen-Holt ?* */ class?hello?implements?Runnable { ????public?void?run() { ????????for(int?i=0;i<10;++i){ ????????????if(count>0){ ????????????????try{ ????????????????????Thread.sleep(1000); ????????????????}catch(InterruptedException e){ ????????????????????e.printStackTrace(); ????????????????} ????????????????System.out.println(count--); ????????????} ????????} ????} ????public?static?void?main(String[] args) { ????????hello he=new?hello(); ????????Thread h1=new?Thread(he); ????????Thread h2=new?Thread(he); ????????Thread h3=new?Thread(he); ????????h1.start(); ????????h2.start(); ????????h3.start(); ????} ????private?int?count=5; }

【運(yùn)行結(jié)果】：

5

4

3

2

1

0

-1

這里出現(xiàn)了-1，顯然這個(gè)是錯(cuò)的。，應(yīng)該票數(shù)不能為負(fù)值。

如果想解決這種問題，就需要使用同步。所謂同步就是在統(tǒng)一時(shí)間段中只有有一個(gè)線程運(yùn)行，

其他的線程必須等到這個(gè)線程結(jié)束之后才能繼續(xù)執(zhí)行。

【使用線程同步解決問題】

采用同步的話，可以使用同步代碼塊和同步方法兩種來完成。

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【同步代碼塊】：

語法格式：

synchronized（同步對(duì)象）{

?//需要同步的代碼

}

但是一般都把當(dāng)前對(duì)象this作為同步對(duì)象。

比如對(duì)于上面的買票的問題，如下：

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/** ?* @author Rollen-Holt ?* */ class?hello?implements?Runnable { ????public?void?run() { ????????for(int?i=0;i<10;++i){ ????????????synchronized?(this) { ????????????????if(count>0){ ????????????????????try{ ????????????????????????Thread.sleep(1000); ????????????????????}catch(InterruptedException e){ ????????????????????????e.printStackTrace(); ????????????????????} ????????????????????System.out.println(count--); ????????????????} ????????????} ????????} ????} ????public?static?void?main(String[] args) { ????????hello he=new?hello(); ????????Thread h1=new?Thread(he); ????????Thread h2=new?Thread(he); ????????Thread h3=new?Thread(he); ????????h1.start(); ????????h2.start(); ????????h3.start(); ????} ????private?int?count=5; }

【運(yùn)行結(jié)果】：（每一秒輸出一個(gè)結(jié)果）

5

4

3

2

1

【同步方法】

也可以采用同步方法。

語法格式為synchronized?方法返回類型方法名（參數(shù)列表）{

??? //?其他代碼

}

現(xiàn)在，我們采用同步方法解決上面的問題。

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33

/** ?* @author Rollen-Holt ?* */ class?hello?implements?Runnable { ????public?void?run() { ????????for?(int?i =?0; i <?10; ++i) { ????????????sale(); ????????} ????} ????public?synchronized?void?sale() { ????????if?(count >?0) { ????????????try?{ ????????????????Thread.sleep(1000); ????????????}?catch?(InterruptedException e) { ????????????????e.printStackTrace(); ????????????} ????????????System.out.println(count--); ????????} ????} ????public?static?void?main(String[] args) { ????????hello he =?new?hello(); ????????Thread h1 =?new?Thread(he); ????????Thread h2 =?new?Thread(he); ????????Thread h3 =?new?Thread(he); ????????h1.start(); ????????h2.start(); ????????h3.start(); ????} ????private?int?count =?5; }

【運(yùn)行結(jié)果】（每秒輸出一個(gè)）

5

4

3

2

1

提醒一下，當(dāng)多個(gè)線程共享一個(gè)資源的時(shí)候需要進(jìn)行同步，但是過多的同步可能導(dǎo)致死鎖。

此處列舉經(jīng)典的生產(chǎn)者和消費(fèi)者問題。

【生產(chǎn)者和消費(fèi)者問題】

先看一段有問題的代碼。

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89

class?Info { ????public?String getName() { ????????return?name; ????} ????public?void?setName(String name) { ????????this.name = name; ????} ????public?int?getAge() { ????????return?age; ????} ????public?void?setAge(int?age) { ????????this.age = age; ????} ????private?String name =?"Rollen"; ????private?int?age =?20; } /** ?* 生產(chǎn)者 ?* */ class?Producer?implements?Runnable{ ????private?Info info=null; ????Producer(Info info){ ????????this.info=info; ????} ????? ????public?void?run(){ ????????boolean?flag=false; ????????for(int?i=0;i<25;++i){ ????????????if(flag){ ????????????????this.info.setName("Rollen"); ????????????????try{ ????????????????????Thread.sleep(100); ????????????????}catch?(Exception e) { ????????????????????e.printStackTrace(); ????????????????} ????????????????this.info.setAge(20); ????????????????flag=false; ????????????}else{ ????????????????this.info.setName("chunGe"); ????????????????try{ ????????????????????Thread.sleep(100); ????????????????}catch?(Exception e) { ????????????????????e.printStackTrace(); ????????????????} ????????????????this.info.setAge(100); ????????????????flag=true; ????????????} ????????} ????} } /** ?* 消費(fèi)者類 ?* */ class?Consumer?implements?Runnable{ ????private?Info info=null; ????public?Consumer(Info info){ ????????this.info=info; ????} ????? ????public?void?run(){ ????????for(int?i=0;i<25;++i){ ????????????try{ ????????????????Thread.sleep(100); ????????????}catch?(Exception e) { ????????????????e.printStackTrace(); ????????????} ????????????System.out.println(this.info.getName()+"<---->"+this.info.getAge()); ????????} ????} } /** ?* 測(cè)試類 ?* */ class?hello{ ????public?static?void?main(String[] args) { ????????Info info=new?Info(); ????????Producer pro=new?Producer(info); ????????Consumer con=new?Consumer(info); ????????new?Thread(pro).start(); ????????new?Thread(con).start(); ????} }

【運(yùn)行結(jié)果】：

Rollen<---->100

chunGe<---->20

chunGe<---->100

Rollen<---->100

chunGe<---->20

Rollen<---->100

Rollen<---->100

Rollen<---->100

chunGe<---->20

chunGe<---->20

chunGe<---->20

Rollen<---->100

chunGe<---->20

Rollen<---->100

chunGe<---->20

Rollen<---->100

chunGe<---->20

Rollen<---->100

chunGe<---->20

Rollen<---->100

chunGe<---->20

Rollen<---->100

chunGe<---->20

Rollen<---->100

chunGe<---->20

大家可以從結(jié)果中看到，名字和年齡并沒有對(duì)于。

?

那么如何解決呢？

1）加入同步

2）加入等待和喚醒

先來看看加入同步會(huì)是如何。

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99

class?Info { ????? ????public?String getName() { ????????return?name; ????} ????public?void?setName(String name) { ????????this.name = name; ????} ????public?int?getAge() { ????????return?age; ????} ????public?void?setAge(int?age) { ????????this.age = age; ????} ????public?synchronized?void?set(String name,?int?age){ ????????this.name=name; ????????try{ ????????????Thread.sleep(100); ????????}catch?(Exception e) { ????????????e.printStackTrace(); ????????} ????????this.age=age; ????} ????? ????public?synchronized?void?get(){ ????????try{ ????????????Thread.sleep(100); ????????}catch?(Exception e) { ????????????e.printStackTrace(); ????????} ????????System.out.println(this.getName()+"<===>"+this.getAge()); ????} ????private?String name =?"Rollen"; ????private?int?age =?20; } /** ?* 生產(chǎn)者 ?* */ class?Producer?implements?Runnable { ????private?Info info =?null; ????Producer(Info info) { ????????this.info = info; ????} ????public?void?run() { ????????boolean?flag =?false; ????????for?(int?i =?0; i <?25; ++i) { ????????????if?(flag) { ????????????????? ????????????????this.info.set("Rollen",?20); ????????????????flag =?false; ????????????}?else?{ ????????????????this.info.set("ChunGe",?100); ????????????????flag =?true; ????????????} ????????} ????} } /** ?* 消費(fèi)者類 ?* */ class?Consumer?implements?Runnable { ????private?Info info =?null; ????public?Consumer(Info info) { ????????this.info = info; ????} ????public?void?run() { ????????for?(int?i =?0; i <?25; ++i) { ????????????try?{ ????????????????Thread.sleep(100); ????????????}?catch?(Exception e) { ????????????????e.printStackTrace(); ????????????} ????????????this.info.get(); ????????} ????} } /** ?* 測(cè)試類 ?* */ class?hello { ????public?static?void?main(String[] args) { ????????Info info =?new?Info(); ????????Producer pro =?new?Producer(info); ????????Consumer con =?new?Consumer(info); ????????new?Thread(pro).start(); ????????new?Thread(con).start(); ????} }

【運(yùn)行結(jié)果】：

Rollen<===>20

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

Rollen<===>20

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

ChunGe<===>100

從運(yùn)行結(jié)果來看，錯(cuò)亂的問題解決了，現(xiàn)在是Rollen?對(duì)應(yīng)20，ChunGe對(duì)于100

，但是還是出現(xiàn)了重復(fù)讀取的問題，也肯定有重復(fù)覆蓋的問題。如果想解決這個(gè)問題，就需要使用Object類幫忙了、

，我們可以使用其中的等待和喚醒操作。

要完成上面的功能，我們只需要修改Info類饑渴，在其中加上標(biāo)志位，并且通過判斷標(biāo)志位完成等待和喚醒的操作，代碼如下：

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class?Info { ????? ????public?String getName() { ????????return?name; ????} ????public?void?setName(String name) { ????????this.name = name; ????} ????public?int?getAge() { ????????return?age; ????} ????public?void?setAge(int?age) { ????????this.age = age; ????} ????public?synchronized?void?set(String name,?int?age){ ????????if(!flag){ ????????????try{ ????????????????super.wait(); ????????????}catch?(Exception e) { ????????????????e.printStackTrace(); ????????????} ????????} ????????this.name=name; ????????try{ ????????????Thread.sleep(100); ????????}catch?(Exception e) { ????????????e.printStackTrace(); ????????} ????????this.age=age; ????????flag=false; ????????super.notify(); ????} ????? ????public?synchronized?void?get(){ ????????if(flag){ ????????????try{ ????????????????super.wait(); ????????????}catch?(Exception e) { ????????????????e.printStackTrace(); ????????????} ????????} ????????? ????????try{ ????????????Thread.sleep(100); ????????}catch?(Exception e) { ????????????e.printStackTrace(); ????????} ????????System.out.println(this.getName()+"<===>"+this.getAge()); ????????flag=true; ????????super.notify(); ????} ????private?String name =?"Rollen"; ????private?int?age =?20; ????private?boolean?flag=false; } /** ?* 生產(chǎn)者 ?* */ class?Producer?implements?Runnable { ????private?Info info =?null; ????Producer(Info info) { ????????this.info = info; ????} ????public?void?run() { ????????boolean?flag =?false; ????????for?(int?i =?0; i <?25; ++i) { ????????????if?(flag) { ????????????????? ????????????????this.info.set("Rollen",?20); ????????????????flag =?false; ????????????}?else?{ ????????????????this.info.set("ChunGe",?100); ????????????????flag =?true; ????????????} ????????} ????} } /** ?* 消費(fèi)者類 ?* */ class?Consumer?implements?Runnable { ????private?Info info =?null; ????public?Consumer(Info info) { ????????this.info = info; ????} ????public?void?run() { ????????for?(int?i =?0; i <?25; ++i) { ????????????try?{ ????????????????Thread.sleep(100); ????????????}?catch?(Exception e) { ????????????????e.printStackTrace(); ????????????} ????????????this.info.get(); ????????} ????} } /** ?* 測(cè)試類 ?* */ class?hello { ????public?static?void?main(String[] args) { ????????Info info =?new?Info(); ????????Producer pro =?new?Producer(info); ????????Consumer con =?new?Consumer(info); ????????new?Thread(pro).start(); ????????new?Thread(con).start(); ????} }

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

【程序運(yùn)行結(jié)果】： Rollen<===>20 ChunGe<===>100 Rollen<===>20 ChunGe<===>100 Rollen<===>20 ChunGe<===>100 Rollen<===>20 ChunGe<===>100 Rollen<===>20 ChunGe<===>100 Rollen<===>20 ChunGe<===>100 Rollen<===>20 ChunGe<===>100 Rollen<===>20 ChunGe<===>100 Rollen<===>20 ChunGe<===>100 Rollen<===>20 ChunGe<===>100 Rollen<===>20 ChunGe<===>100 Rollen<===>20 ChunGe<===>100 Rollen<===>20 先在看結(jié)果就可以知道，之前的問題完全解決。

《完》

轉(zhuǎn)載于:https://www.cnblogs.com/ftkwm/p/5934003.html

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