Dhia Series – Learn JDBC xws li yog piv txwv
Txheej txheem cej luam
Nyob rau cov tshooj no peb yuav tham txog qhov JDBC feature yog muab los ntawm lub caij nplooj ntoos hlav moj khaum. Peb yuav tsum ywm ntau rau ntawm ib sab yuav siv thiab configuration. Taw qhia no yuav pab tus developers kom ua raws li cov kauj ruam nram thiab siv cov JDBC siv caij nplooj ntoos hlav moj khaum.
DAO kuj
DAO stands rau tej ntaub ntawv saib yam twj paj nruas uas yog siv kev sis raug zoo database. DAOs nyob ua ib ke muab ib txhais tau tias nyeem thiab sau ntawv rau tus database thiab lawv yuav tsum tau las no functionality mus txog tus interface uas tas hauv daim ntawv thov yuav saib tau lawv.
Caij nplooj ntoos hlav JBDC
Caij nplooj ntoos hlav tau nws xwb moj JDBC khaum uas pab peb so JDBC chaws los ntawm shouldering cov xwm txheej tshwj fwm thiab tuav kev ua yuam kev. Qhov yoojyim koj xav mloog zoo rau cov nqe lus thiab queries tau koj cov ntaub ntawv mus thiab los ntawm cov database.
Caij nplooj ntoos hlav cov ntaub ntawv coj teeb ib hoob hu ua JdbcTemplate template. Ib JdbcTemplate tsuas yog Datasource yuav pib ua hauj lwm.
Hauv qab no snippet cai qhia tau hais tias tus creation ntawm JdbcTemplate.
JdbcTemplate template = JdbcTemplate tshiab(myDataSource);
Nram qab no snippet cai qhia tau hais tias cov kev thaiv ntawm DAO taum nrog JdbcTemplate.
<taum daim id =”jdbcTemplate”
hoob =”org.springframework.jdbc.core.JdbcTemplate”>
<lub npe ntawm tus kheej =”dataSource”><nyob taum =”dataSource”/></khoom>
</taum>
<taum daim id =”studentDao” hoob =”StudentDaoJdbc”>
<lub npe ntawm tus kheej =”jdbcTemplate”><nyob taum =”jdbcTemplate”/></khoom>
</taum>
<taum daim id =”courseDao” hoob =”CourseDaoJdbc”>
<lub npe ntawm tus kheej =”jdbcTemplate”><nyob taum =”jdbcTemplate”/></khoom>
</taum>
Nram no yog ib qho piv txwv ntawm tus txheejtxheem qhov siv lub caij nplooj hlav JDBC template database.
- Tus thawj tivthaiv yog ib interface (StudentDAO) rau txhais kom meej qhov twg mas yuav muab los siv. Ntawm no yog ib los ntxig rau tus menyuam kawm ntawv kom paub meej.
pob com.techalpine.dao;
pej xeem interface StudentDAO {
pej xeem tsis muaj dabtsis insertStudent(Txoj hlua, Txoj hlua);
}
- Tus tom ntej tivthaiv yog yuav siv hoob kawm ntawm tus interface mentioned saum toj noj (StudentDAOImpl). Nws implements cov tso nrog rau txoj kev siv JDBC template.
pob com.techalpine.dao;
ntshuam java.sql.ResultSet;
ntshuam java.sql.SQLException;
ntshuam javax.sql.DataSource;
ntshuam org.springframework.jdbc.core.JdbcTemplate;
ntshuam org.springframework.jdbc.core.RowMapper;
pej xeem hoob StudentDAOImpl implements StudentDAO {
lwm yam JdbcTemplate jdbcTemplate;
pej xeem tsis muaj dabtsis setDataSource(DataSource dataSource) {
this.jdbcTemplate = JdbcTemplate tshiab(dataSource);
}
pej xeem tsis muaj dabtsis insertStudent(Txoj hlua npe, Chaw nyob txoj hlua) {
// Thov qhia cov lus nug SQL rau tsab ntawv nrog thaum
Cov lus nug txoj hlua = “NTXIG RAU TUS MENYUAM KAWM NTAWV (lub npe,chaw nyob) QHOV TSEEM CEEB (?,?)”;
// Thov qhia qhov qauv yog hu ua
jdbcTemplate.update(lus nug, Nruas tshiab[] );
}
}
- Cov kev tivthaiv thib peb yog cov ntaub ntawv configuration (xml) los txhais cov ntaub ntawv tau qhov twg los thiab wiring cov noob taum.
<?xml version =”1.0″ encoding =”UTF-8″?>
<taum xmlns =”http://www.springframework.org/schema/beans”
xmlns:xsi =”http://www.w3.org/2001/XMLSchema-instance”xsi:schemaLocation =”http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/Spring-beans.xsd”>
<taum daim id =”dataSource” ua kom puas txujci =”kaw” hoob =”org.apache.commons.dbcp.BasicDataSource”>
<lub npe ntawm tus kheej =”driverClassName” tus nqi =”org.hsqldb.jdbcDriver”/>
<lub npe ntawm tus kheej =”url” tus nqi =”jdbc:hsqldb:hsql://localhost”/>
<lub npe ntawm tus kheej =”username” tus nqi =”techalpine”/>
<lub npe ntawm tus kheej =”lo lus zais” tus nqi =”techalpine”/>
</taum>
<taum daim id =”studentDAO” hoob =”com.techalpine.dao.StudentDAOImpl”>
<lub npe ntawm tus kheej =”dataSource” nyob =”dataSource”/>
</taum>
</taum>
- Tam sim no ib sab kawg yog ib hoob kawm standalone java (java) sim cov pawg. Cov tseem ceeb hauv chav kawm ntawv retrieve taum hauv thawv caij nplooj ntoos hlav thiab ces hu rau tus tso nrog rau cov qauv los ntxig rau cov me nyuam kawm ntawv cov ntaub ntawv.
pob com.techalpine.dao;
ntshuam org.springframework.context.ApplicationContext;
ntshuam org.springframework.context.support.ClassPathXmlApplicationContext;
pej xeem hoob kawm {
pej xeem tsis muaj dabtsis loj zoo li qub(Txoj hlua[] args) {
ApplicationContext lub ntsiab lus teb = ClassPathXmlApplicationContext tshiab(“Student.xml”);
StudentDAO studentDAO = (StudentDAO) context.getBean(“studentDAO”);
studentDAO.insertStudent(“Amit”,”Delhi”);
}
}
Xaus
Qhov tsab xov xwm no yog rau cov developers uas xav mus dhia mus coding tsis taug ntau lub caij taug nyoog rau ib sab theoretical. Peb sim tau rau ib sab theoretical cia yam tsawg kawg nkaus thiab qhia ntxiv ntawm coding thiab configuration. Vam tias tej zaum qhov no yuav pab tus txiv developers zej zog.
