DBUtils的使用

import com.kastiny.orm.domain.User;
import org.apache.commons.beanutils.BeanUtils;
import org.apache.commons.beanutils.ConvertUtils;
import org.apache.commons.beanutils.Converter;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.*;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.File;
import java.io.FileFilter;
import java.sql.*;
import java.util.List;
import java.util.Map;

public class App {

    QueryRunner qr = null;
    Connection conn = null;

    @Before
    public void before() throws Exception {
        Class.forName("com.mysql.jdbc.Driver");
        conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/chatroom", "root", "");
        qr = new QueryRunner();
    }


    /**
     * 获取数据库表中name列的值，并以List返回
     * @throws Exception
     */
    @Test
    public void testGetColumnList() throws Exception {
        List<String> ls = (List<String>) qr.query(conn, "select * from user", new ColumnListHandler("name"));
        System.out.println(ls);
    }

    /**
     * 获取返回记录的的给定字段值,如果没有给定字段则返回第一个字段的值
     * 如果返回多条记录，择取第一条记录rs.next();
     * @throws Exception
     */
    @Test
    public void testGetField() throws Exception {
        String name = (String) qr.query(conn, "select * from user", new ScalarHandler("name"));
        System.out.println(name);
    }

    /**
     * 将返回的记录以Map形式返回，【返回的map中key的值会根据执行的sql来定，如果某字段有别名则取用别名，如果没有则使用表的字段名，全部使用小写】
     * 如果返回结果包含多条记录，则取其第一条：rs.next();
     * return : {id=1, name=aa, pass=aa, addr=安徽, info=hehe, type=0}
     * @throws Exception
     */
    @Test
    public void testSelectMap() throws Exception {
//        Map map = qr.query(conn, "select * from user where id=1", new MapHandler());
        Map map = qr.query(conn, "select * from user", new MapHandler());
        System.out.println(map);
    }

    /**
     * 将每条记录转成Map并存放于List
     * 结果形式：[{key1:value1,key2:value2},{key1:value1,key2:value2}]，
     * @throws Exception
     */
    @Test
    public void testSelectMapList() throws Exception {
        List<Map<String, Object>> maps = qr.query(conn, "select * from user", new MapListHandler());
        for(Map<String, Object> map : maps) {
          System.out.println(map);
        }
    }

    /**
     * 将返回记录转成指定的对象
     * 如果返回结果包含多个记录，则取其第一条：rs.next();
     * @throws Exception
     */
    @Test
    public void testSelectBean() throws Exception {
        User user = qr.query(conn, "select * from user where id=1", new BeanHandler<User>(User.class));
        System.out.println(user);
    }

    /**
     * 将每条记录转成指定的对象并存放于List中
     * @throws Exception
     */
    @Test
    public void testSelectBeanList() throws Exception {
        List<User> users = qr.query(conn, "select * from user", new BeanListHandler<User>(User.class));
        for(User user : users) {
            System.out.println(user);
        }
    }

}