JDBC Template - 基础篇
- execute：DDL语句，如：建表、修改表结构
- update、batchUpdate：增删改
- query、queryXXX：查
- call：存储过程
案例一：
package com.imooc.sc.dao;
import com.imooc.sc.entity.Course;
import com.imooc.sc.entity.Student;
import java.util.List;
public interface CourseDao {
void insert(Course course);
void update(Course course);
void delete(int id);
Course select(int id);
List selectAll();
}
package com.imooc.sc.dao.impl;
import com.imooc.sc.dao.CourseDao;
import com.imooc.sc.entity.Course;
import com.imooc.sc.entity.Student;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.stereotype.Repository;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
@Repository
public class CourseDaoImpl implements CourseDao {
@Autowired
private JdbcTemplate jdbcTemplate;
public void insert(Course course) {
String sql = "insert into course(name,score) values(?,?)";
jdbcTemplate.update(sql,course.getName(),course.getScore());
}
public void update(Course course) {
String sql = "update course set name=?,score=? where id=?";
jdbcTemplate.update(sql,course.getName(),course.getScore(),course.getId());
}
public void delete(int id) {
String sql = "delete from course where id=?";
jdbcTemplate.update(sql,id);
}
public Course select(int id) {
String sql = "select * from course where id=?";
return jdbcTemplate.queryForObject(sql,new CourseRowMapper(),id);
}
public List selectAll() {
String sql = "select * from course";
return jdbcTemplate.query(sql,new CourseRowMapper());
}
private class CourseRowMapper implements RowMapper {
public Course mapRow(ResultSet resultSet, int i) throws SQLException {
Course course = new Course();
course.setId(resultSet.getInt("id"));
course.setName(resultSet.getString("name"));
course.setScore(resultSet.getInt("score"));
return course;
}
}
} 案例二：
package com.imooc.sc.dao;
import com.imooc.sc.entity.Selection;
import java.util.List;
import java.util.Map;
public interface SelectionDao {
void insert(List seles);
void delete(int sid,int cid);
List> selectByStudent(int sid);
List> selectByCourse(int cid);
} package com.imooc.sc.dao.impl;
import com.imooc.sc.dao.SelectionDao;
import com.imooc.sc.entity.Selection;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Repository;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
@Repository
public class SelectionDaoImpl implements SelectionDao {
@Autowired
private JdbcTemplate jdbcTemplate;
public void insert(List seles) {
String sql = "insert into selection values(?,?,?,?)";
List list = new ArrayList();
for(Selection sel:seles){
Object[] args = new Object[4];
args[0] = sel.getSid();
args[1]=sel.getCid();
args[2] = sel.getSelTime();
args[3] =sel.getScore();
list.add(args);
}
jdbcTemplate.batchUpdate(sql,list);
}
public void delete(int sid,int cid) {
String sql = "delete from selection where student=? and course=?";
jdbcTemplate.update(sql,sid,cid);
}
public List> selectByStudent(int sid) {
String sql = "select se.*,stu.name sname,cou.name cname from selection se " +
"left join student stu on se.student=stu.id " +
"left join course cou on se.course=cou.id" +
"where student=?";
return jdbcTemplate.queryForList(sql,sid);
}
public List> selectByCourse(int cid) {
String sql = "select se.*,stu.name sname,cou.name cname from selection se " +
"left join student stu on se.student=stu.id " +
"left join course cou on se.course=cou.id" +
"where course=?";
return jdbcTemplate.queryForList(sql,cid);
}
} 案例三：
package com.imooc.sc.dao;
import com.imooc.sc.entity.Student;
import java.util.List;
public interface StudentDao {
void insert(Student stu);
void update(Student stu);
void delete(int id);
Student select(int id);
List selectAll();
} package com.imooc.sc.dao.impl;
import com.imooc.sc.dao.StudentDao;
import com.imooc.sc.entity.Student;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.stereotype.Repository;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
@Repository
public class StudentDaoImpl implements StudentDao {
@Autowired
private JdbcTemplate jdbcTemplate;
public void insert(Student stu) {
String sql = "insert into student(name,sex,born) values(?,?,?)";
jdbcTemplate.update(sql,stu.getName(),stu.getSex(),stu.getBorn());
}
public void update(Student stu) {
String sql = "update student set name=?,sex=?,born=? where id=?";
jdbcTemplate.update(sql,stu.getName(),stu.getSex(),stu.getBorn(),stu.getId());
}
public void delete(int id) {
String sql = "delete from student where id=?";
jdbcTemplate.update(sql,id);
}
public Student select(int id) {
String sql = "select * from student where id=?";
return jdbcTemplate.queryForObject(sql,new StudentRowMapper(),id);
}
public List selectAll() {
String sql = "select * from student";
return jdbcTemplate.query(sql,new StudentRowMapper());
}
private class StudentRowMapper implements RowMapper {
public Student mapRow(ResultSet resultSet, int i) throws SQLException {
Student stu = new Student();
stu.setId(resultSet.getInt("id"));
stu.setName(resultSet.getString("name"));
stu.setSex(resultSet.getString("sex"));
stu.setBorn(resultSet.getDate("born"));
return stu;
}
}
} 优点：
- 简单、灵活：封装了 JDBC API。缺点：
- Java代码和SQL代码混合：使得后端不能很好的和数据库端分离开发，影响开发效率。
- 功能不丰富：1、分页；2、关联关系。总结：JDBC只能是相对于JDBC API开发前进了一小步，但是还不足够强大到真正的ORM关系。JDBC Template是Spring框架对JDBC操作的封装，简单、灵活但不够强大。实际应用中还需要和其它ORM框架混合使用。