JavaEE 之 DBCP

1.DBCP

　　a.定义：DBCP（DataBase Connection Pool）数据库连接池，是java数据库连接池的一种，由Apache开发，通过数据库连接池，可以让程序自动管理数据库连接的释放和断开

　　b.配置：

　　<bean id="dataSource" destroy-method="close" class="org.apache.commons.dbcp.BasicDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver" />
        <property name="url" value="jdbc:mysql://localhost:3306/emp" />
        <property name="username" value="root" />
        <property name="password"  value="admin"/>
        <property name="maxActive" value="10"></property>
        <property name="initialSize" value="2"></property>
        <property name="minIdle" value="2"></property>
        <property name="maxIdle" value="3"></property>
    </bean>

    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource" />
    </bean>

　　c.使用：

@Repository
public class UserDao  {
    @Resource
    private JdbcTemplate template;

        //增
    public void addUser(String name,String pwd){
        int userType=1;
        String sql="insert into users(user_name,user_pwd,user_type) values(?,?,?)";
        jdbcTemplate.update(sql,new Object[]{name,pwd,userType});
    }

        //删
    public void delUserById(int id){
        String sql="delete from users where user_id=?";
        jdbcTemplate.update(sql,new Object[]{id});
    }

        //改
    public void updateUser(User user){
        String sql="update users set user_name=?,user_pwd=?,user_type=? where user_id=?";
        jdbcTemplate.update(sql,new Object[]{user.getUserName(),user.getUserPwd(),user.getUserType(),user.getUserId()});
    }

        //查——方法一
    public List<User> findAllUser(){
    　　String sql="select * from users";
    　　List<User> list=jdbcTemplate.query(sql,new BeanPropertyRowMapper(User.class));
    　　return list;
    }    

        //查——方法二
    public List<User> getAllUser(){
        String sql="select * from users";
        List<User> list=jdbcTemplate.query(sql,new RowMapper(){

            @Override
            public Object mapRow(ResultSet arg0, int arg1) throws SQLException {
                User u=new User();
                if(arg0!=null){
                u.setUserId(arg0.getInt("user_id"));
                u.setUserName(arg0.getString("user_name"));
                u.setUserPwd(arg0.getString("user_pwd"));
                u.setUserId(arg0.getInt("user_type"));
                }
                return u;
            }

        });
        return list;
    }

    //多表联查
    public List<User> getAllUserAndInfo(){
        String sql="select u.user_name,u.user_type,i.info_nickName,i.info_email from users u left join userInfo i on u.user_id=i.user_id ";
        List<User> list=jdbcTemplate.query(sql,new RowMapper(){

            @Override
            public Object mapRow(ResultSet arg0, int arg1) throws SQLException {
                User u=new User();
                if(arg0!=null){
                u.setUserName(arg0.getString("user_name"));
                u.setUserType(arg0.getInt("user_type"));
                UserInfo info=new UserInfo();
                info.setInfoEmail(arg0.getString("info_email"));
                info.setInfoNickName(arg0.getString("info_nickName"));
                u.setInfo(info);
                }
                return u;
            }

        });
        return list;
    }

}