BasicDao的使用

本次博客带领大家学习BasicDao的使用。

BasicDao的基本说明

1. DAO：data access object数据访问对象。
2. 这样的通用类，称为BasicDao，是专门和数据库交互的，即完成对数据库(表)的crud操作。
3. 在BasicDao 的基础上，实现一张表对应一个Dao，更好的完成功能，比如Customer表-Customer.java类(javabean)-Customer.java。

BasicDAO 应用实例

1. dao_.utils //工具类

public class JDBCUtilsByDruid {
    private  static DataSource ds;

    //在静态代码块完成 ds初始化
    static {
        Properties properties = new Properties();
        try {
            properties.load(new FileInputStream("src\\druid.properties"));
            ds = DruidDataSourceFactory.createDataSource(properties);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    //编写getConnection 方法
    public static Connection getConnection() throws SQLException {
        return ds.getConnection();
    }

    //关闭连接，在数据库连接池技术中，close不是真的断掉连接，而是把使用的Connection对象放回连接池
    public static void close(ResultSet resultSet, Statement statement,Connection connection){
        try {
            if (resultSet != null){
                resultSet.close();
            }
            if (statement !=null){
                statement.close();
            }
            if (connection !=null){
                connection.close();
            }
        } catch (SQLException e) {
            throw  new RuntimeException(e);
        }
    }
}

2. dao_.domain //javabean

public class Actor {
    private Integer id;
    private String name;
    private String sex;
    private Date borndate;
    private String phone;

    public Actor() {
    }

    public Actor(Integer id, String name, String sex, Date borndate, String phone) {
        this.id = id;
        this.name = name;
        this.sex = sex;
        this.borndate = borndate;
        this.phone = phone;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public Date getBorndate() {
        return borndate;
    }

    public void setBorndate(Date borndate) {
        this.borndate = borndate;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    @Override
    public String toString() {
        return "\nActor{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", sex='" + sex + '\'' +
                ", borndate=" + borndate +
                ", phone='" + phone + '\'' +
                '}';
    }
}

3. dao_.dao //存放XxxDAO 和 BasicDAO

public class BasicDAO<T> { //泛型指定具体类型

    private QueryRunner qr=new QueryRunner();

    //开发通用的dml方法，针对任意的表
    public int update(String sql,Object... paramenters){
        Connection connection = null;
        try {
            connection = JDBCUtilsByDruid.getConnection();
            int update = qr.update(connection, sql, paramenters);
            return update;
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }finally {
            JDBCUtilsByDruid.close(null,null,connection);
        }
    }

    //返回多个对象(即查询的结果是多行),针对任意表
    public List<T> queryMulti(String sql,Class<T> clazz,Object... paramenters){

        Connection connection = null;
        try {
            connection = JDBCUtilsByDruid.getConnection();
            return qr.query(connection, sql, new BeanListHandler<T>(clazz),paramenters);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }finally {
            JDBCUtilsByDruid.close(null,null,connection);
        }
    }

    //查询单行结果的通用方法
    public T querySingle(String sql,Class<T> clazz,Object... paramenters){
        Connection connection = null;
        try {
            connection = JDBCUtilsByDruid.getConnection();
            return qr.query(connection, sql, new BeanHandler<T>(clazz),paramenters);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }finally {
            JDBCUtilsByDruid.close(null,null,connection);
        }
    }

    //查询单行单列的方法，即返回单值的方法
    public Object queryScalar(String sql,Object... paramenters){
        Connection connection = null;
        try {
            connection = JDBCUtilsByDruid.getConnection();
            return qr.query(connection, sql, new ScalarHandler(),paramenters);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }finally {
            JDBCUtilsByDruid.close(null,null,connection);
        }
    }
}

public class ActorDAO extends BasicDAO<Actor> {
    //1.就有 BasicDAO 的方法
    //2.根据业务需求，可以编写特有的方法。
}

4. dao_.test //写测试类

public class TestDAO {
    //测试ActorDAO 对actor表crud操作
    @Test
    public void testActorDAO(){
        ActorDAO actorDAO = new ActorDAO();
        // 1. 查询
        List<Actor> actors = actorDAO.queryMulti("select * from actor where id >=?", Actor.class, 1);
        System.out.println("====查询结果===");
        for (Actor actor : actors){
            System.out.println(actor);
        }

        //2. 查询单行记录
        Actor actor = actorDAO.querySingle("select * from actor where id =?", Actor.class, 6);
        System.out.println("====查询单行结果====");
        System.out.println(actor);

        //3.查询单行单列
        Object o = actorDAO.queryScalar("select name from actor where id = ?", 6);
        System.out.println("=====查询单行单列值====");
        System.out.println(o);

        //4.dml操作 insert,update,delete
        int update = actorDAO.update("insert into actor values(null,?,?,?,?)", "张无忌", "男", "2000-11-11", "999");

        System.out.println(update >0 ? "执行成功" : "执行没有影响结果");
    }
}