JDBC - dbutils工具包

引入

处理返回结果 handlers

测试

package com.atguigu5.dbutils;
import java.sql.Connection;
import java.sql.Date;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import java.util.Map;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.ResultSetHandler;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.MapHandler;
import org.apache.commons.dbutils.handlers.MapListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;
import org.junit.Test;
import com.atguigu2.bean.Customer;
import com.atguigu4.util.JDBCUtils;
/*
 * commons-dbutils 是 Apache 组织提供的一个开源 JDBC工具类库,封装了针对于数据库的增删改查操作
 * 
 */
public class QueryRunnerTest {
    //测试插入
    @Test
    public void testInsert() {
        Connection conn = null;
        try {
            QueryRunner runner = new QueryRunner();
            conn = JDBCUtils.getConnection3();
            String sql = "insert into customers(name,email,birth)values(?,?,?)";
            int insertCount = runner.update(conn, sql, "蔡徐坤","caixukun@126.com","1997-09-08");
            System.out.println("添加了" + insertCount + "条记录");
        } catch (SQLException e) {
            e.printStackTrace();
        }finally{
            JDBCUtils.closeResource(conn, null);
        }
    }
    //测试查询
    /*
     * BeanHander:是ResultSetHandler接口的实现类，用于封装表中的一条记录。
     */
    @Test
    public void testQuery1(){
        Connection conn = null;
        try {
            QueryRunner runner = new QueryRunner();
            conn = JDBCUtils.getConnection3();
            String sql = "select id,name,email,birth from customers where id = ?";
            BeanHandler<Customer> handler = new BeanHandler<>(Customer.class);
            Customer customer = runner.query(conn, sql, handler, 23);
            System.out.println(customer);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
            JDBCUtils.closeResource(conn, null);
        }
    }
    /*
     * BeanListHandler:是ResultSetHandler接口的实现类，用于封装表中的多条记录构成的集合。
     */
    @Test
    public void testQuery2() {
        Connection conn = null;
        try {
            QueryRunner runner = new QueryRunner();
            conn = JDBCUtils.getConnection3();
            String sql = "select id,name,email,birth from customers where id < ?";
            BeanListHandler<Customer>  handler = new BeanListHandler<>(Customer.class);
            List<Customer> list = runner.query(conn, sql, handler, 23);
            list.forEach(System.out::println);
        } catch (SQLException e) {
            e.printStackTrace();
        }finally{
            JDBCUtils.closeResource(conn, null);
        }
    }
    /*
     * MapHander:是ResultSetHandler接口的实现类，对应表中的一条记录。
     * 将字段及相应字段的值作为map中的key和value
     */
    @Test
    public void testQuery3(){
        Connection conn = null;
        try {
            QueryRunner runner = new QueryRunner();
            conn = JDBCUtils.getConnection3();
            String sql = "select id,name,email,birth from customers where id = ?";
            MapHandler handler = new MapHandler();
            Map<String, Object> map = runner.query(conn, sql, handler, 23);
            System.out.println(map);
        } catch (SQLException e) {
            e.printStackTrace();
        }finally{
            JDBCUtils.closeResource(conn, null);
        }
    }
    /*
     * MapListHander:是ResultSetHandler接口的实现类，对应表中的多条记录。
     * 将字段及相应字段的值作为map中的key和value。将这些map添加到List中
     */
    @Test
    public void testQuery4(){
        Connection conn = null;
        try {
            QueryRunner runner = new QueryRunner();
            conn = JDBCUtils.getConnection3();
            String sql = "select id,name,email,birth from customers where id < ?";
            MapListHandler handler = new MapListHandler();
            List<Map<String, Object>> list = runner.query(conn, sql, handler, 23);
            list.forEach(System.out::println);
        } catch (SQLException e) {
            e.printStackTrace();
        }finally{
            JDBCUtils.closeResource(conn, null);
        }
    }
    /*
     * ScalarHandler:用于查询特殊值
     */
    @Test
    public void testQuery5(){
        Connection conn = null;
        try {
            QueryRunner runner = new QueryRunner();
            conn = JDBCUtils.getConnection3();
            String sql = "select count(*) from customers";
            ScalarHandler handler = new ScalarHandler();
            Long count = (Long) runner.query(conn, sql, handler);
            System.out.println(count);
        } catch (SQLException e) {
            e.printStackTrace();
        }finally{
            JDBCUtils.closeResource(conn, null);
        }
    }
    @Test
    public void testQuery6(){
        Connection conn = null;
        try {
            QueryRunner runner = new QueryRunner();
            conn = JDBCUtils.getConnection3();
            String sql = "select max(birth) from customers";
            ScalarHandler handler = new ScalarHandler();
            Date maxBirth = (Date) runner.query(conn, sql, handler);
            System.out.println(maxBirth);
        } catch (SQLException e) {
            e.printStackTrace();
        }finally{
            JDBCUtils.closeResource(conn, null);
        }
    }
    /*
     * 自定义ResultSetHandler的实现类
     */
    @Test
    public void testQuery7(){
        Connection conn = null;
        try {
            QueryRunner runner = new QueryRunner();
            conn = JDBCUtils.getConnection3();
            String sql = "select id,name,email,birth from customers where id = ?";
            ResultSetHandler<Customer> handler = new ResultSetHandler<Customer>(){
                @Override
                public Customer handle(ResultSet rs) throws SQLException {
//                    System.out.println("handle");
//                    return null;
//                    return new Customer(12, "成龙", "Jacky@126.com", new Date(234324234324L));
                    if(rs.next()){
                        int id = rs.getInt("id");
                        String name = rs.getString("name");
                        String email = rs.getString("email");
                        Date birth = rs.getDate("birth");
                        Customer customer = new Customer(id, name, email, birth);
                        return customer;
                    }
                    return null;
                }
            };
            Customer customer = runner.query(conn, sql, handler,23);
            System.out.println(customer);
        } catch (SQLException e) {
            e.printStackTrace();
        }finally{
            JDBCUtils.closeResource(conn, null);
        }
    }
}

关闭

    public static void closeResource1(Connection conn,Statement ps,ResultSet rs){
        DbUtils.closeQuietly(conn);
        DbUtils.closeQuietly(ps);
        DbUtils.closeQuietly(rs);
    }