Java: Aiki tare da fayiloli - rubuce-rubuce, karatu, shafewa

Java yana da yawa kayayyakin aiki, don aiki tare da fayiloli, saboda su bauta a matsayin mangaza na data a da yawa shirye-shirye. Sau da yawa sosai damar zuwa fayil din da ake bukata a cikin Java Android. All azuzuwan don aiki tare da fayiloli dake a cikin java.io kunshin, wadda aka kuma adana azuzuwan don aiki tare da shigar da fitarwa daga qarqashinsu. Tsananin magana, Java aiki tare da fayiloli auku farko via da byte da kuma halin shigar da fitarwa daga qarqashinsu. A togiya a cikin wannan yanayin ne aji fayil. Daga shi kuma za a fara.

Class fayil Java - Aiki tare da Files

Fayil aji interacts kai tsaye tare da fayiloli da fayil tsarin. An misali na wannan aji da ake amfani da farko don samun damar da kaddarorin fayil da kuma kewaya da matsayi na subdirectories. An ba m da hanyoyin da extracting da adanar bayanai a wani fayil, amma tare da wannan aji, za ka iya samun mai yawa bayanai game da fayil kwanan wata, lokaci, damar izini da shugabanci hanya. A gaskiya ma, cikin fayil aji abu ne fassarar fayil ko shugabanci a Java.

Don ƙirƙirar wani misali daga cikin fayil, ta amfani da daya daga cikin constructors: File (Kirtani hanyar zuwa babban fayil, Kirtani filename).

La'akari da ainihin dabaru na wannan aji, kyale su samu bayanai game da wani fayil, ko directory:

• getName () - dawo da sunan fayil.
• akwai () - kõma a Boolean gaskiya, idan da akwai fayil, ko karya a gaban hali.
• isFile () - kayyade ko da abu na nufin wani fayil, ya dawo da m ma'ana darajar.
• isDirectory () - kõma gaskiya, idan shi ne babban fayil.
• canWrite () - kõma gaskiya, idan da fayil shi ne writable.
• canRead () - kõma gaskiya, idan da fayil shi ne zaa iya karanta.
• setReadOnly () - sa fayil na karanta kawai;
• tsawon () - dawo da file size a bytes.
• renameTo (File wani sabon sunan) - renames yanzu fayil daidai da muhawara. Koma gaskiya, idan da aiki shi ne nasara.
• share () - share fayil ko babban fayil (idan ta fanko), wanda ya nuna da mai kira.
• jerin () - retrieves jerin abu sunayen adana a cikin shugabanci, kamar yadda a jere tsararru (m kawai kundayen).

Saboda haka, ta hanyar amfani da fayil aji aka bayar a Java aiki tare da fayiloli da manyan fayiloli.

Aiki tare da fayiloli ta azuzuwan FileInputStream da FileOutputStream

Tun da farko da muka ambata cewa za'ayi yafi ta hanyar shigar da fitarwa kõguna a Java aiki tare da fayiloli. Byte kõguna na fayiloli gabatar a cikin nau'i na azuzuwan FileInputStream da FileOutputStream. Wadannan azuzuwan, su ne magada daga cikin tushe m azuzuwan InputStream da OutputStream bi da bi, don haka hanyoyin da wadannan azuzuwan suna samuwa ga aiki tare da fayiloli.

La'akari da farko da FileInputStream. Kaya daga wannan aji aka gabatar a kasa:

A farko constructor daukan matsayin shaida daga cikin fayil hanyar matsayin kirtani, da kuma na biyu - a cikin irin abu misali. Ko da yake da farko constructor da ake amfani da mafi sau da yawa a karo na biyu idan yana yiwuwa su yi nazarin da kaddarorin fayil samuwa a cikin fayil aji hanyoyin. Idan ka ƙirƙiri wani misali daga cikin aji FileInputStream ya buɗe wani labari rafi domin karanta fayil.

Class FileOutputStream constructors aka nuna a kasa:

A halin da ake ciki shi ne kama wani FileInputStream, amma shi kuma iya daukar mai ma'ana darajar "jimlar", wanda, a lokacin da gaskiya ya nuna cewa bayanan da aka rubuta zuwa ga manufa fayil za a saka wa data kasance, da kuma idan ƙarya - zai tafi da cikakken overwrite fayil, watau, da haihuwa data za a ajiye su.

Bari mu dubi wani misali ta amfani da wadannan azuzuwan:

The labari rafi FileInputStream file1.txt karanta data daga fayil byte da byte ta Hanyar karanta (). Kowane byte karanta aka adana a wani m, a lamba form. Bugu da ari, a cikin jiki na cikin yayin da madauki , wannan m an shige a matsayin shaida rubuta wani misali Hanyar FileOutputStream, wanda ya rubuta da samu byte a file2.txt fayil. A karshen biyu qarqashinsu compulsorily rufe ta hanyar kusa.

Classes FileReader da FileWriter

Idan lalle kun sani cẽwa lõkacin da aiki tare fayiloli, za ku yi aiki da su da rubutu, shi ya sa hankali domin amfani da harafin maimakon byte qarqashinsu. Wadannan gudana an gabatar da azuzuwan FileReader da FileWriter a Java. Aiki tare da fayiloli ta amfani da wadannan azuzuwan faruwa game da wannan kamar yadda a baya hali. Wadannan azuzuwan zuriyarta Reader kuma marubuci bi da bi, wanda ayyana asali hanyoyin domin data shigar da fitarwa.

Designers azuzuwan FileReader da FileWriter aka gabatar a kasa:

Yarda, da bambance-bambance a cikin ilimin harsuna idan aka kwatanta da byte koguna kusan m. A kasa line ne cewa wadannan azuzuwan ake musamman tsara aiki tare da haruffa a Unicode, ba zai iya yi byte qarqashinsu. Wannan hanya Java da aka shirya a aikin da fayiloli. Misali na data azuzuwan da aka ba a kasa:

Kamar yadda ka gani, da bambance-bambance ba su kiyaye. Ya kamata a lura cewa ko da yake kwarara hali, da karanta Hanyar dawo, da kuma rubuta Hanyar daukan wani lamba darajar. Ko da yake rubuta Hanyar sa hannu ya shafi karbar int irin shawara aka rubuta a cikin rafi, kawai ƙananan 16 ragowa, alamomin kamar wakilci a Java ne kamar haka da yawan ragowa.

ƙarshe

Saboda haka, mun tattauna muhimman azuzuwan don aiki tare da fayiloli a Java. Shi ne ya kamata a lura da cewa idan da za ku ci gaba software don Java Android, za ka iya amince amfani da wannan kayan aiki.