Spring JDBC use

1, Why Spring JDBC package offered?

　　Because Spring provides a complete template class and a base class to simplify the development, we only need a small amount of code to write.

2, examples to explain

The first step: introducing dependent mysql-connector spring-jdbc spring-tx spring-core spring-beans spring-context like

The second step: the establishment of a database, configuration xml

The third step: Get jdbcTemplate objects

　　Can be obtained by

 private JdbcTemplate jdbcTemplate;

    public void setDataSource(DataSource dataSource){
        this.jdbcTemplate=new JdbcTemplate(dataSource);
}　

<bean id="userDao" class="com.test.jdbc.dao.impl.UserDaoImpl">
        <property name="dataSource" ref="dataSource"/>
</bean>

　　Can inherit JdbcDaoSupport, use super.getJdbcTemplate () to obtain

Step Four: Use jdbcTemplate object CRUD

　　CRUD use Update (), the parameters of this method, one of the first sql statement, followed by a variable parameter, passed sql statement placeholder

　　Query using queryForObject () method of the first parameter is a parameter in sql required to achieve the third parameter RowMapper interface objects,

　　　　For the result set, this method requires a single object returns

　　query () method returns the collection of objects

public class UserDaoImpl extends JdbcDaoSupport implements IUserDao {

    public void save(User user) {
        super.getJdbcTemplate().update("insert into user(id,username,password,date,salary) values(null,?,?,?,?)",
                user.getUsername(),user.getPassword(),user.getDate(),user.getSalary());

    }

    public void update(User user) {
        super.getJdbcTemplate().update("update user set username=?,password=?,date=?,salary=? where id=?",
                user.getUsername(), user.getPassword(), user.getDate(), user.getSalary(), user.getId());

    }

    public void delete(Integer id) {
        super.getJdbcTemplate().update("delete from user where id=?",id);
    }

    public User findById(Integer id) {
       /* List<User> user = super.getJdbcTemplate().query("select * from user where id=?", new Object[]{id},
                new RowMapper<User>() {
                    @Override
                    public User mapRow(ResultSet resultSet, int i) throws SQLException {
                        User user = new User();
                        user.setId(resultSet.getInt("id"));
                        user.setDate(resultSet.getDate("date"));
                        user.setUsername(resultSet.getString("username"));
                        user.setPassword(resultSet.getString("password"));
                        user.setSalary(resultSet.getBigDecimal("salary"));
                        return user;
                    }
                    //方法的返回值会直接封装到集合中
                });
        return user.size()>0?user.get(0):null;*/

        User user = super.getJdbcTemplate().queryForObject("select * from user where id=?", new Object[]{id},
                new RowMapper<User>() {
                    @Override
                    public User mapRow(ResultSet resultSet, int i) throws SQLException {
                        User user = new User();
                        user.setId(resultSet.getInt("id"));
                        user.setDate(resultSet.getDate("date"));
                        user.setUsername(resultSet.getString("username"));
                        user.setPassword(resultSet.getString("password"));
                        user.setSalary(resultSet.getBigDecimal("salary"));
                        return user;
                    }
                });
        return user;
    }

    public List<User> findAll() {
        List<User> users = super.getJdbcTemplate().query("select * from user",
                new RowMapper<User>() {
                    @Override
                    public User mapRow(ResultSet resultSet, int i) throws SQLException {
                        User user = new User();
                        user.setId(resultSet.getInt("id"));
                        user.setDate (ResultSet.getDate ( "DATE" ));
                        user.setUsername(resultSet.getString( "username" )); 
                        user.setPassword (resultSet.getString ( "password" )); 
                        user.setSalary (ResultSet.getBigDecimal ( "the salary" ));
                         return User ; 
                    } 
                    // the return value of the method will be set encapsulates 
                });
         return Users; 
    } 

}

3, JdbcTemplate JDBC type is the central core of the package

　　Knowledge inquiry address:

　　https://docs.spring.io/spring-framework/docs/current/spring-framework-reference/data-access.html#jdbc