DAO支持抽象类【理解】【操作】

1.使用统一的DAO支持抽象类，可以简化开发过程，数据层实现类继承JdbcDaoSupport

public class UserDAO extends JdbcDaoSupport{…}

2.为该类注入DataSource

<bean id="userDao" class="cn.itcast.jdbc.template.UserDAO">

<!-- 必须为继承JdbcDaoSupport的类注入JdbcTemplate，变量名为jdbcTemplate --> <!-- <property name="jdbcTemplate" ref="jdbcTemplate"/> -->

<!-- 还可以注入DataSource对象，由JdbcDaoSupport自动创建JdbcTemplate对象 --> <property name="dataSource" ref="dataSource"/>

</bean>

3.在DAO实现类中使用this.getJdbcTemplate()获取模板对象

4.JdbcTemplate API

增删改

update(sql,Object... args)

查询数据为单一结果数据

queryFor* 获取简单类型数据

Long queryForLong(sql,Object... args)

Interget queryForInt(sql,Object... args)

Double queryForDouble(sql,Object... args)

queryForObject 获取引用类型数据(不是全部)

Object<T> queryForLong(sql,查询数据的类型class,Object... args)

查询数据为全部字段的单一数据

queryForObject

Object queryForObject(sql,查询数据结果行映射接口对象,Object... args) 查询数据为全部字段的多条数据

query

List<T> query (sql,查询数据结果行映射接口对象,Object... args)

行映射接口制作

private class 自定义内部类类名 implements RowMapper<实体泛型>{ public User mapRow(ResultSet rs, int rownum) throws SQLException { User u = new User(); //实体

通过原始的jdbc查询结果集对象ResultSet获取查询的数据 u.setUuid(rs.getLong("uuid"));

u.setUserName(rs.getString("userName"));

u.setAge(rs.getInt("age"));

return u;

}

}

标准DAO制作范例：

public void add(UserModel um){

String sql = "insert into tbl_user (userName,age) values(?,?)";

this.getJdbcTemplate().update(sql, um.getUserName(),um.getAge());

}

public void delete(UserModel um){

String sql = "delete from tbl_user where uuid = ?"; this.getJdbcTemplate().update(sql, um.getUuid()); } public void update(UserModel um){ String sql = "update tbl_user set userName = ? , age = ? where uuid = ?"; this.getJdbcTemplate().update(sql, um.getUserName(),um.getAge(),um.getUuid()); } //查询一共多少条数据 public Integer getCount(){ String sql = "select count(uuid) from tbl_user"; return this.getJdbcTemplate().queryForInt(sql); } //按照uuid查名字 public String getNameByUuid(Long uuid){ String sql = "select userName from tbl_user where uuid = ?"; return this.getJdbcTemplate().queryForObject(sql,String.class,uuid); } //查询某个数据 public UserModel getByUuid(Long uuid){ String sql = "select * from tbl_user where uuid = ?"; RowMapper<UserModel> rm = new RowMapper<UserModel>() { public UserModel mapRow(ResultSet rs, int rowNum)throws SQLException { UserModel um = new UserModel(); um.setUuid(rs.getLong("uuid")); um.setUserName(rs.getString("userName")); return um; } }; return this.getJdbcTemplate().queryForObject(sql, rm, uuid); } //查询全部数据 public List<UserModel> getAll(){ String sql = "select * from tbl_user"; RowMapper<UserModel> rm = new RowMapper<UserModel>() { public UserModel mapRow(ResultSet rs, int rowNum)throws SQLException { UserModel um = new UserModel(); um.setUuid(rs.getLong("uuid")); um.setUserName(rs.getString("userName")); return um; } }; return this.getJdbcTemplate().query(sql, rm); }