java JDBC (七) org.apache.commons.dbutils 查询

package cn.sasa.demo1;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.List;
import java.util.Map;

import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.ArrayHandler;
import org.apache.commons.dbutils.handlers.ArrayListHandler;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.ColumnListHandler;
import org.apache.commons.dbutils.handlers.MapHandler;
import org.apache.commons.dbutils.handlers.MapListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;

import cn.sasa.demo5.DBProperties;

public class ResultSetHandlerDemo {
    static Connection conn = null;
    static {
        try {
            conn = DBProperties.getConnection();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public static void main(String[] args) throws SQLException {
        //arrayHandler();
        //arrayListHandler();
        //beanHandler();
        //beanListHandler();
        //columnListHandler();
        //scalarHandler();
        //mapHandler();
        mapListHandler();
    }
    /**
     * ArrayHandler 获取一行
     */
    static void arrayHandler() throws SQLException {
        QueryRunner query = new QueryRunner();
        String sql = "SELECT * FROM product WHERE pid=?;";
        Object[] objArr = query.query(conn, sql, new ArrayHandler(),4);
        for(Object obj : objArr) {
            System.out.println(obj);
        }
    }

    /**
     * ArrayListHandler
     */
    static void arrayListHandler() throws SQLException {
        QueryRunner query = new QueryRunner();
        String sql = "SELECT * FROM product WHERE pid<?;";
        List<Object[]> objList = query.query(conn, sql, new ArrayListHandler(),4);
        for(Object[] objArr : objList) {
            for(Object obj : objArr) {
                System.out.print(obj);
                System.out.print("\t");
            }
            System.out.println("");
        }
    }

    /**
     * BeanHandler
     * 封装成JavaBean对象，JavaBean对象必须有空参构造函数
     */
    static void beanHandler() throws SQLException {
        QueryRunner query = new QueryRunner();
        String sql = "SELECT * FROM product;";
        Product product = query.query(conn, sql, new BeanHandler<Product>(Product.class));
        System.out.println(product.getPname());
    }

    /**
     * 转成一个对象集合
     */
    static void beanListHandler() throws SQLException {
        QueryRunner query = new QueryRunner();
        String sql = "SELECT * FROM product WHERE pid<?;";
        List<Product> objList = query.query(conn, sql, new BeanListHandler<Product>(Product.class),4);
        for(Product obj : objList) {
            System.out.println(obj.getPname());
        }
    }

    /**
     * columnListHandler
     * 指定列的数据存到集合
     */
    static void columnListHandler() throws SQLException {
        QueryRunner query = new QueryRunner();
        String sql = "SELECT * FROM product WHERE pid<?;";
        List<Object> objList = query.query(conn, sql, new ColumnListHandler<Object>("pname"),4);
        for(Object obj : objList) {
            System.out.println(obj);
        }
    }

    /**
     * ScalarHandler 获取单行单列的结果集
     */
    static void scalarHandler() throws SQLException {
        QueryRunner query = new QueryRunner();
        String sql = "SELECT COUNT(*) AS row_count FROM product WHERE pid<?;";
        Object obj = query.query(conn, sql, new ScalarHandler<Object>(),4);
        System.out.println(obj);
    }

    /**
     * MapHandler 将第一行结果集封装到Map集合中
     * 键：列名
     * 值：列中的数据
     * @throws SQLException
     */
    static void mapHandler() throws SQLException {
        QueryRunner query = new QueryRunner();
        String sql = "SELECT * FROM product";
        Map<String, Object> map = query.query(conn, sql, new MapHandler());
        for(String key : map.keySet()) {
            System.out.println(map.get(key).toString());
        }
    }

    /**
     * MapListHandler
     * 结果集的每一行 列：值 存到 Map集合的 键：值
     * Map集合再存到List集合中
     * @throws SQLException
     */
    static void mapListHandler() throws SQLException {
        QueryRunner query = new QueryRunner();
        String sql = "SELECT * FROM product";
        List<Map<String,Object>> mapList = query.query(conn, sql, new MapListHandler());
        for(int i=0; i<mapList.size(); i++) {

            for(String key : mapList.get(i).keySet()) {
                System.out.print("key:" + key + " val:" + mapList.get(i).get(key) + "\t");
            }
            System.out.println("");
        }
    }
}

package cn.sasa.demo1;

public class Product {
    private int pid;
    private String pname;
    private double price;
    private String ptype;
    private String create_tm;

    public Product() {}
    public Product(int pid, String pname,double price,
            String ptype, String create_tm) {
        this.pid = pid;
        this.pname = pname;
        this.price = price;
        this.ptype = ptype;
        this.create_tm = create_tm;
    }
    public int getPid() {
        return pid;
    }
    public void setPid(int pid) {
        this.pid = pid;
    }
    public String getPname() {
        return pname;
    }
    public void setPname(String pname) {
        this.pname = pname;
    }
    public double getPrice() {
        return price;
    }
    public void setPrice(double price) {
        this.price = price;
    }
    public String getPtype() {
        return ptype;
    }
    public void setPtype(String ptype) {
        this.ptype = ptype;
    }
    public String getCreate_tm() {
        return create_tm;
    }
    public void setCreate_tm(String create_tm) {
        this.create_tm = create_tm;
    }
}