Imiyalo yokwenza isicelo seJava elula ku-Unix
Izinto Ezinkulu NgeJava
I-Java iyihlelo lokuzimela elizimele lokuthuthukiswa kwesofthiwe. Iqukethe ulimi lwezinhlelo, izinhlelo zosizo nezindawo zokugijima. Uhlelo lweJava lungathuthukiswa kwikhompyutha eyodwa futhi lugijime kunoma iyiphi enye ikhompyutha enezikhathi ezifanele zokugijima. Ngokuvamile, izinhlelo ze-Java ezindala zingasebenza ezindaweni ezintsha zokugijima. I-Java ithole ngokwanele ukuthi ngisho nezinhlelo zokusebenza eziyinkimbinkimbi kakhulu zingabhalwa ngaphandle kokuxhomekeka kohlelo lokusebenza. Lokhu kubizwa nge-Java% 100.
Ngokuthuthukiswa kwe-intanethi i-Java ithole ukuthandwa, ngoba uma uhlela iWebhu, awunayo indlela yokwazi ukuthi iyiphi indlela umsebenzisi angaba ngayo. Ngelimi lohlelo lwe-Java, ungasebenzisa "ukubhala kanye, ugijime noma kuphi" iparadigm. Lokhu kusho ukuthi uma uhlanganisa uhlelo lwakho lwe-Java, awukhiqiza imiyalo yesikhulumi esisodwa esithile. Esikhundleni salokho, udala ikhodi ye-Java ye-byte, okuwukuthi, imiyalelo yeMishini Ye-Java Virtual (i-Java VM). Kubasebenzisi, akunandaba ukuthi yiyiphi ipulatifomu abayisebenzisayo- Windows, Unix , MacOS, noma isiphequluli se-intanethi-uma nje ine-Java VM, iyaqonda lawo ma-byte amakhodi.
Izinhlobo ezintathu zezinhlelo zeJava
- "I-applet" uhlelo lwe-Java olwenzelwe ukuthi lufakwe ekhasini lewebhu.
- "I-servlet" uhlelo lwe-Java olwenzelwe ukuba lusebenze kuseva.
Kulezi zimo ezimbili uhlelo lwe-Java alukwazi ukugijima ngaphandle kwezinsizakalo zesiphequluli sewebhu se-applet noma iseva yeWebhu ye-servlet.
- "Uhlelo lokusebenza lwe-Java" luhlelo lwe-Java olungasetshenziswa ngokwalo.
Lezi ziqondiso ezilandelayo zenzelwe ukuthi uhlele uhlelo lwe-Java usebenzisa ikhompyutha esekelwe ku-Unix.
Uhla lokuhlola
Kulula kakhulu, udinga izinto ezimbili kuphela zokubhala uhlelo lwe-Java:
(1) I-Java 2 Platform, Standard Edition (J2SE), eyayibizwa ngokuthi iJava Development Kit (JDK).
Landa inguqulo yakamuva ye-Linux. Qiniseka ukuthi ulanda i-SDK, hhayi i-JRE (i-JRE ifakiwe ku-SDK / J2SE).
(2) Umhleli wombhalo
Cishe noma yikuphi umhleli owutholayo kuma-platforms ase-Unix asekelwe (isib. Vi, Emacs, Pico). Sizosebenzisa i-Pico njengesibonelo.
Isinyathelo 1. Dala ifayela lomthombo we-Java.
Ifayela lomthombo liqukethe umbhalo obhalwe ngolimi lwe-Java. Ungasebenzisa noma yimuphi umhleli wombhalo ukudala nokuhlela amafayela omthombo.
Unezinketho ezimbili:
* Ungagcina ifayela le-FatCalories.java (ekupheleni kwalesi sihloko) kukhompyutha yakho. Le ndlela ingakusiza ukuthayipha okuthile. Khona-ke, ungahamba ngqo ku-step 2.
* Noma, ungalandela imiyalo ende:
(1) Veza igobolondo (ngezinye izikhathi ebizwa ngokuthi ukuphela) iwindi.
Uma isikhangiso sokuqala sivela, isiqondisi sakho samanje sivame ukuba isiqondisi sakho sasekhaya. Ungashintsha isiqondisi sakho samanje esiqondisweni sakho sasekhaya nganoma isiphi isikhathi ngokuthayipha i-cd ngesikhathi esheshayo (ngokuvamile "%") bese ucindezela ukubuya.
Amafayela weJava oyidala kufanele agcinwe kuhla lwemibhalo ehlukile. Ungakha isiqondisi ngokusebenzisa umyalo mkdir . Isibonelo, ukwakha isiqondisi se-java kumhlahlandlela wakho wasekhaya, uzoqala ukushintsha isiqondisi sakho samanje esiqondisweni sakho sasekhaya ngokufaka umyalo olandelayo:
% cd
Khona-ke, ungangena umyalo olandelayo:
% mkdir java
Ukuze ushintshe isiqondisi sakho samanje kulolu hlu lwemibhalo entsha, uzobe ufaka: % cd java
Manje ungaqala ukudala ifayela lakho lomthombo.
(2) Qala umhleli we-Pico ngokuthayipha i-pico ngokushesha bese ucindezela ukubuyisa. Uma uhlelo luphendula ngomyalezo we-pico: umyalo awutholakali , khona-ke i-Pico cishe ayitholakali. Bheka umlawuli wakho wesistimu ngolwazi oluthe xaxa, noma sebenzisa omunye umhleli.
Uma uqala i-Pico, izobonisa imbumbulu entsha, engenalutho. Le yindawo ozoyibhala ngayo ikhodi yakho.
(3) Thayipha ikhodi evezwe ekupheleni kwalesi sihloko (ngaphansi kwe- "Uhlelo lwe-Java yesampula") engxenyeni engenalutho. Thayipha konke njengoba kubonisiwe. Umqambi we-Java nomhumushi banecala.
(4) Londoloza ikhodi ngokuthayipha i-Ctrl-O. Uma ubona igama lefayela libhalwa :, thayipha u-FatCalories.java, olandelwe yilawula lapho ufuna khona ifayela. Uma ufisa ukusindisa i-FatCalories.java ku-directory / ekhaya / smith / java, uzobe uthayipha
/home/smith/java/FatCalories.java bese ucindezela u-Return.
Sebenzisa i-Ctrl-X ukuze uphume ku-Pico.
Isinyathelo 2. Qalisa ifayela lomthombo.
Umqambi weJava, i-javac, uthatha ifayela lakho lomthombo futhi uhumusha umbhalo walo ngemiyalo yokuthi i-Java Virtual Machine (Java VM) ingaqonda. I-compiler ibeka le miyalo ibe ifayela lekhodi ye-byte.
Manje, khuphula elinye iwindi legobolondo. Ukuze uhlanganise ifayela lakho lomthombo, shintsha isiqondisi sakho samanje esiqondisweni lapho ifayela lakho litholakala khona. Isibonelo, uma isiqondisi somthombo wakho / ekhaya / smith / java, ungayiphayipha umyalo olandelayo ku-prompt bese ucindezela Buyela:
% cd / ekhaya / smith / java
Uma ufaka i-pwd ngesikhathi esheshayo, kufanele ubone isiqondisi samanje, esikulesi sibonelo sishintshiwe sibe / ekhaya / smith / java.
Uma ufaka i-ls ngokushesha, kufanele ubone ifayela lakho: FatCalories.java.
Manje ungaqoqa. Ngesikhathi esheshayo, thayipha umyalo olandelayo bese ucindezela i-Return: javac FatCalories.java
Uma ubona lo mlayezo wephutha:
i-javac: ayitholakali
ke i-Unix ayikwazi ukuthola i-Java compiler, i-javac.
Nansi indlela eyodwa yokutshela u-Unix lapho uthola khona i-javac. Ake sithi ufake i-Java 2 Platform (J2SE) ku /usr/java/jdk1.4. Ngesikhathi esheshayo, thayipha umyalo olandelayo bese ucindezela i-Return:
/usr/java/jdk1.4/javac FatCalories.java
I-compiler manje ikhiqize ifayela lekhodi ye-byte ye-Java: FatCalories.class.
Ngesikhathi esheshayo, thayipha uhlobo ls ukuqinisekisa ifayela elisha likhona.
Isinyathelo 3. Qalisa Uhlelo
I-Java VM isetshenziswa ngumhumushi weJava okuthiwa i-java. Lo mhumushi uthatha ifayela lakho lekhodi ye-byte futhi wenza imiyalelo ngokuyihumusha ibe imiyalelo ikhompyutha yakho engayiqonda.
Kumqondisi ofanayo, faka ku-prompt:
I-java FatCalories
Uma ugijima uhlelo udinga ukungena izinombolo ezimbili uma iwindi lomugqa womyalo omnyama livela. Loluhlelo kufanele lubhale lezo zinombolo ezimbili kanye nephesenti elihlanganiswe nguhlelo.
Uma uthola umlayezo wephutha:
Ukungafani emcimbini "main" java.lang.NoClassDefFoundError: FatCalories
Kusho ukuthi: i-java ayikwazi ukuthola ifayela lakho lekhodi ye-byte, i-FatCalories.class.
Okufanele ukwenze: Enye yezindawo uJava uzama ukuthola ifayela lakho lekhodi ye-byte yincwadi yakho yamanje. Isibonelo, uma ifayela lakho lekhodi ye-byte likhona / ekhaya / smith / java, kufanele ushintshe isiqondisi sakho samanje kulokho ngokuthayipha umyalo olandelayo ku-prompt bese hit Buyela:
cd / ekhaya / smith / java
Uma ufaka i-pwd ngokushesha, kufanele ubone / ekhaya / smith / java. Uma ufaka i-ls ngokushesha, kufanele ubone amafayili akho eFatCalories.java kanye neFatCalories.class. Manje faka i-java FatCalories futhi.
Uma usenenkinga, kungadingeka ushintshe ukushintsha kwakho kwe-CLASSPATH. Ukuze ubone ukuthi lokhu kuyadingeka, zama "ukulungisa" i-classpath ngomyalo olandelayo:
susa i-CLASSPATH
Manje faka i-java FatCalories futhi. Uma uhlelo lusebenza manje, kuzodingeka ushintshe ukushintsha kwakho kwe-CLASSPATH.