Spring框架对JDBC的简单封装。提供了一个JDBCTemplate对象简化JDBC的开发java
导入jar包spring
建立JdbcTemplate对象。依赖于数据源DataSource
* JdbcTemplate template = new JdbcTemplate(ds);sql
调用JdbcTemplate的方法来完成CRUD的操做
* update():执行DML语句。增、删、改语句
* queryForMap():查询结果将结果集封装为map集合,将列名做为key,将值做为value 将这条记录封装为一个map集合
* 注意:这个方法查询的结果集长度只能是1
* queryForList():查询结果将结果集封装为list集合
* 注意:将每一条记录封装为一个Map集合,再将Map集合装载到List集合中
* query():查询结果,将结果封装为JavaBean对象
* query的参数:RowMapper
* 通常咱们使用BeanPropertyRowMapper实现类。能够完成数据到JavaBean的自动封装
* new BeanPropertyRowMapper<类型>(类型.class)
* queryForObject:查询结果,将结果封装为对象
* 通常用于聚合函数的查询数据库
获取数据库链接池的工具类app
package JDBC; import com.alibaba.druid.pool.DruidDataSourceFactory; import javax.sql.DataSource; import java.io.IOException; import java.io.InputStream; import java.sql.Connection; import java.sql.SQLException; import java.sql.Statement; import java.util.Properties; public class DruidUtils { private static DataSource dataSource=null; //获取数据库链接池 public static DataSource getDataSource() { return dataSource; } //关闭statement,归还connection public static void close(Statement statement, Connection connection){ if (statement!=null){ try { statement.close(); } catch (SQLException e) { e.printStackTrace(); } } if (connection!=null){ try { connection.close(); } catch (SQLException e) { e.printStackTrace(); } } } public static void setDataSource(DataSource dataSource) { DruidUtils.dataSource = dataSource; } static { try { //加载配置文件经内存 Properties properties = new Properties(); InputStream resourceAsStream = DruidUtils.class.getClassLoader().getResourceAsStream("druid.properties"); properties.load(resourceAsStream); dataSource = DruidDataSourceFactory.createDataSource(properties); } catch (IOException e) { System.out.println(e); } catch (Exception e) { e.printStackTrace(); } } public static Connection getConnection() throws SQLException { return dataSource.getConnection(); } }
查询全部记录,将其封装为Emp对象的List集合框架
package JDBC; import org.springframework.jdbc.core.BeanPropertyRowMapper; import org.springframework.jdbc.core.JdbcTemplate; import javax.sql.DataSource; import java.sql.SQLException; import java.util.List; public class Template { public static void main(String[] args) throws SQLException { //获取数据库链接池 DataSource dataSource = DruidUtils.getDataSource(); //获取template对象 JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource); //定义sql语句 String sql="select *from count"; //执行sql List<Person> list = jdbcTemplate.query(sql, new BeanPropertyRowMapper<Person>(Person.class)); for (Person person : list) { System.out.println(person); } } }
@Test public void test2(){ String sql = "insert into emp(id,ename,dept_id) values(?,?,?)"; int count = template.update(sql, 1015, "郭靖", 10); System.out.println(count); }
@Test public void test3(){ String sql = "delete from emp where id = ?"; int count = template.update(sql, 1015); System.out.println(count); }
@Test public void test4(){ String sql = "select * from emp where id = ? or id = ?"; Map<String, Object> map = template.queryForMap(sql, 1001,1002); System.out.println(map); //{id=1001, ename=孙悟空, job_id=4, mgr=1004, joindate=2000-12-17, salary=10000.00, bonus=null, dept_id=20} }
@Test public void test5(){ String sql = "select * from emp"; List<Map<String, Object>> list = template.queryForList(sql); for (Map<String, Object> stringObjectMap : list) { System.out.println(stringObjectMap); } }
@Test public void test6(){ String sql = "select * from emp"; List<Emp> list = template.query(sql, new RowMapper<Emp>() { @Override public Emp mapRow(ResultSet rs, int i) throws SQLException { Emp emp = new Emp(); int id = rs.getInt("id"); String ename = rs.getString("ename"); int job_id = rs.getInt("job_id"); int mgr = rs.getInt("mgr"); Date joindate = rs.getDate("joindate"); double salary = rs.getDouble("salary"); double bonus = rs.getDouble("bonus"); int dept_id = rs.getInt("dept_id"); emp.setId(id); emp.setEname(ename); emp.setJob_id(job_id); emp.setMgr(mgr); emp.setJoindate(joindate); emp.setSalary(salary); emp.setBonus(bonus); emp.setDept_id(dept_id); return emp; } }); for (Emp emp : list) { System.out.println(emp); } }
@Test public void test7(){ String sql = "select count(id) from emp"; Long total = template.queryForObject(sql, Long.class); System.out.println(total); }
以上就是Template的一些知识点,若有错误还请各位批评指正,喜欢个人能够点赞收藏加关注,嘻嘻