Spring笔记05(Spring JDBC三种数据源和ORM框架的映射)
2024-08-28 15:04:19
1.ORM框架的映射
01.JDBC连接数据库以前的方式代码,并给对象赋值
@Test
/**
* 以前的方式jdbc
*/
public void TestJdbc(){
/**
* 连接数据库的四要素
*/
String driver="com.mysql.jdbc.Driver";
String url="jdbc:mysql://localhost:3306/spring";
String username="root";
String password="";
/**
* 创建jdbc需要的api
*/
Connection connection=null;
PreparedStatement pst=null;
ResultSet rs=null; try {
//01加载驱动
Class.forName(driver);
//02获取链接
connection= DriverManager.getConnection(url, username, password);
//03书写sql语句
String sql="select sid,sname,age from student where sid=?";
//04给参数赋值
pst=connection.prepareStatement(sql);
pst.setInt(,);
//05获取查询结果
rs=pst.executeQuery(); while(rs.next()){
Student student=new Student();
student.setSid(rs.getInt("sid"));
student.setAge(rs.getInt("age"));
student.setSname(rs.getString("sname"));
System.out.println(student);
} } catch (Exception e) {
e.printStackTrace();
}finally{
try {
rs.close();
pst.close();
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
} }
02.我们使用反射机制来 动态的给 Student对象赋值
/**
* 我们使用反射机制来 动态的给 Student对象赋值
*/
public static void main(String[] args){
/**
* 连接数据库的四要素
*/
String driver="com.mysql.jdbc.Driver";
String url="jdbc:mysql://localhost:3306/spring";
String username="root";
String password=""; /**
* 创建jdbc需要的api
*/
Connection connection=null;
PreparedStatement pst=null;
ResultSet rs=null; //创建需要映射的实体类
Object student=null;
try {
student=Class.forName("cn.pb.bean.Student").newInstance();
} catch (Exception e) {
e.printStackTrace();
} try {
//01.加载驱动
Class.forName(driver);
//02.获取连接
connection=DriverManager.getConnection(url,username,password);
//03.书写sql语句
String sql="select sid,age,sname from student where sid=?";
//04.给参数赋值
pst=connection.prepareStatement(sql);
pst.setInt(,);
//05.返回结果
rs=pst.executeQuery(); while (rs.next()){
//获取元数据的结果集 元数据:描述数据的数据
ResultSetMetaData metaData = rs.getMetaData();
System.out.println("元数据"+metaData);
int columnCount = metaData.getColumnCount();
//遍历元数据集合
for (int i=;i<=columnCount;i++){
//获取数据库字段的名称
String columnName = metaData.getColumnName(i);
//获取数据库字段的类型 返回的类型都是大写
String columnTypeName = metaData.getColumnTypeName(i); /**
* 01.给我一个元数据的名称
* 02.我去实体类中找对应的setXxx()
*/
String method = getMethod(columnName);
//赋值的时候根据类型
if(columnTypeName.equals("INT")){
student.getClass().getMethod(method,int.class).invoke(student,rs.getInt(columnName));
}else if(columnTypeName.equals("VARCHAR")){
student.getClass().getMethod(method,String.class).invoke(student,rs.getString(columnName));
} } Student stu= (Student) student;
System.out.println(stu);
} } catch (Exception e) {
e.printStackTrace();
}finally {
try {
rs.close();
pst.close();
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
} } /**
* 01.用户给我一个字段名称(数据库中)
* 02.我们返回一个set+字段名 (首字母大写)
* @param name 字段名称
* @return 返回的set方法名称
*/
public static String getMethod(String name){//传过来sid 返回 setSid return "set"+name.substring(,).toUpperCase()+name.substring();
}
2.Spring的JDBC:
01.实体类代码:
package cn.pb.bean; /**
* student的实体类
*/
public class Student { private int sid;
private int age;
private String sname; public Student(int sid, int age, String sname) {
this.sid = sid;
this.age = age;
this.sname = sname;
} public Student(int age, String sname) {
this.age = age;
this.sname = sname;
} public Student() { } public int getSid() {
return sid;
} public void setSid(int sid) {
this.sid = sid;
} public int getAge() {
return age;
} public void setAge(int age) {
this.age = age;
} public String getSname() {
return sname;
} public void setSname(String sname) {
this.sname = sname;
} @Override
public String toString() {
return "Student{" +
"sid=" + sid +
", age=" + age +
", sname='" + sname + '\'' +
'}';
}
}
02.dao层代码:
001.dao层代码
package cn.pb.dao; import cn.pb.bean.Student; import java.util.List; public interface StudentDao {
int addStudent(Student student);
int delStudent(Student student);
int updateStudent(Student student);
List<Student> findAllStudents();
}
002.daoImpl层代码
package cn.pb.dao.impl; import cn.pb.bean.Student;
import cn.pb.dao.StudentDao;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.core.support.JdbcDaoSupport; import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
/**
* Spring 有一个类叫 JdbcDaoSupport ===>BaseDao
* JdbcDaoSupport有一个属性叫JdbcTemplate
* 在创建JdbcTemplate的时候 需要一个DataSource
*
* 我们只需要在配置文件中 配置数据源 即可!
*
*/
public class StudentDaoImpl extends JdbcDaoSupport implements StudentDao { public int addStudent(Student student) {
String sql="insert into student(sname,age) values(?,?)";
return getJdbcTemplate().update(sql,student.getSname(),student.getAge());
} public int delStudent(Student student) {
String sql="delete from student where sid=?";
return getJdbcTemplate().update(sql,student.getSid());
} public int updateStudent(Student student) {
String sql="update student set sname=?,age=? where sid=?";
return getJdbcTemplate().update(sql,student.getSname(),student.getAge(),student.getSid());
}
/**
* @return 行映射器 rowMapper
*/
public List<Student> findAllStudents() {
String sql="select * from student";
return getJdbcTemplate().query(sql, new StudentRowMapper() { });
}
}
行映射器代码:
package cn.pb.dao.impl; import cn.pb.bean.Student;
import org.springframework.jdbc.core.RowMapper; import java.sql.ResultSet;
import java.sql.SQLException; public class StudentRowMapper implements RowMapper<Student> {
/**
*
* @param resultSet 之前叫 返回数据的结果集,是所有数据
* 现在 这个不是所有,是一行数据的结果集
*/
public Student mapRow(ResultSet resultSet, int i) throws SQLException {
Student student=new Student();
student.setSid(resultSet.getInt("sid"));
student.setSname(resultSet.getString("sname"));
student.setAge(resultSet.getInt("age"));
return student;
}
}
03.service层代码:
001.service层代码:
package cn.pb.service; import cn.pb.bean.Student; import java.util.List; public interface StudentService {
int addStudent(Student student);
int delStudent(Student student);
int updateStudent(Student student);
List<Student> findAllStudents(); }
002.serviceImpl层代码
package cn.pb.service.impl; import cn.pb.bean.Student;
import cn.pb.dao.StudentDao;
import cn.pb.service.StudentService; import java.util.List; public class StudentServiceImpl implements StudentService {
private StudentDao dao; public int addStudent(Student student) {
return dao.addStudent(student);
} public int delStudent(Student student) {
return dao.delStudent(student);
} public int updateStudent(Student student) {
return dao.updateStudent(student);
} public List<Student> findAllStudents() {
return dao.findAllStudents();
} public StudentDao getDao() {
return dao;
} public void setDao(StudentDao dao) {
this.dao = dao;
}
}
04.连接数据库的properties文件:jdbc.properties
jdbc.driverClass=com.mysql.jdbc.Driver
jdbc.jdbcUrl=jdbc:mysql://localhost:3306/spring
jdbc.userName=root
jdbc.password=
05.applicationContext.xml文件:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:c="http://www.springframework.org/schema/c"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd"> <!--01.加载jdbc.properties文件-->
<context:property-placeholder location="classpath:jdbc.properties"/> <!--02.配置数据源-->
<!--001.使用spring默认的数据源
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="${jdbc.driverClass}"/>
<property name="url" value="${jdbc.jdbcUrl}"/>
<property name="username" value="${jdbc.userName}"/>
<property name="password" value="${jdbc.password}"/>
</bean>-->
<!--002.使用c3p0数据源
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
<property name="driverClass" value="${jdbc.driverClass}"/>
<property name="jdbcUrl" value="${jdbc.jdbcUrl}"/>
<property name="user" value="${jdbc.userName}"/>
<property name="password" value="${jdbc.password}"/>
</bean>-->
<!--003.使用dbcp数据源-->
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
<property name="driverClassName" value="${jdbc.driverClass}"/>
<property name="url" value="${jdbc.jdbcUrl}"/>
<property name="username" value="${jdbc.userName}"/>
<property name="password" value="${jdbc.password}"/>
</bean>
<!--03.配置dao 在StudentDaoImpl里要使用数据源-->
<bean id="studentDaoImpl" class="cn.pb.dao.impl.StudentDaoImpl">
<property name="dataSource" ref="dataSource"/>
</bean> <!--04.配置service-->
<bean id="studentServiceImpl" class="cn.pb.service.impl.StudentServiceImpl">
<property name="dao" ref="studentDaoImpl"/>
</bean>
</beans>
06.测试代码:
package cn.pb; import cn.pb.bean.Student;
import cn.pb.service.StudentService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; import java.util.List; public class TestJdbc { public static void main(String[] args) {
ApplicationContext context=new
ClassPathXmlApplicationContext("applicationContext.xml");
StudentService service= (StudentService) context.getBean("studentServiceImpl");
//service.addStudent(new Student(25,"xixi"));
List<Student> list=service.findAllStudents();
System.out.println(list);
}
}
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