QueryRunner的添加与查询操作

Apache-DBUtils实现CRUD操作，commmons-dbutils是Apache组织提供的开源JDBC工具类，

封装了针对于数据库的增删改查操作，Class QueryRunner

TestQueryRunner

package com.aff.util;
import java.sql.Connection;
import java.sql.Date;
import java.util.List;
import java.util.Map;
import org.apache.commons.dbutils.QueryRunner;
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.aff.bean.Customer;
//commmons-dbutils是Apache组织提供的一个开源的jdbc工具类库，
//封装了针对于数据库的增删改查操作
public class TestQueryRunner {
    // 测试插入
    @Test
    public void testInsert() {
        Connection conn = null;
        try {
            QueryRunner runner = new QueryRunner();
            conn = JDBCUtilsDruid.getConnection();
            String sql = "insert into customers (name,email,birth)values(?,?,?)";
            runner.update(conn, sql, "蔡徐坤", "cxk@126.com", "1997-2-24");
            System.out.println("添加成功");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCUtilsDruid.closeResource(conn, null, null);
        }
    }

    // 测试查询
    // ResultSetHandler 是个接口
    // 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 = JDBCUtilsDBCP.getConnection();
            String sql = "select  id,name,birth from customers where id =?";
            BeanHandler<Customer> handler = new BeanHandler<>(Customer.class);
            Customer customer = runner.query(conn, sql, handler, 20);
            System.out.println(customer);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCUtilsDBCP.closeResource(conn, null, null);
        }
    }

    // BeanListHander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() throws Exception {
        Connection conn = null;
        try {
            QueryRunner runner = new QueryRunner();
            conn = JDBCUtilsC3P0.getConnection();
            String sql = "select  id,name,birth from customers where id <?";
            BeanListHandler<Customer> handler = new BeanListHandler<>(Customer.class);
            List<Customer> list = runner.query(conn, sql, handler, 20);
            list.forEach(System.out::println);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCUtilsC3P0.closeResource(conn, null, 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
    // 键--值 键--值 体现 key-value
    // {name=何苗苗, birth=1996-02-03, id=20}
    @Test
    public void testQuery3() throws Exception {
        Connection conn = null;
        try {
            QueryRunner runner = new QueryRunner();
            conn = JDBCUtilsC3P0.getConnection();
            String sql = "select  id,name,birth from customers where id =?";
            MapHandler handler = new MapHandler();
            Map<String, Object> map = runner.query(conn, sql, handler, 20);
            System.out.println(map);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCUtilsC3P0.closeResource(conn, null, null);
        }
    }

    // MapListHander是ResultSetHandler接口的实现类，对应表中的多条记录
    // 将字段及相应的值作为map中的key和value，将这些map添加到list中
    @Test
    public void testQuery4() throws Exception {
        Connection conn = null;
        try {
            QueryRunner runner = new QueryRunner();
            conn = JDBCUtilsC3P0.getConnection();
            String sql = "select  id,name,birth from customers where id <?";
            MapListHandler listHandler = new MapListHandler();
            List<Map<String, Object>> list = runner.query(conn, sql, listHandler, 20);
            list.forEach(System.out::println);
            /*
              {name=朱茵, birth=2014-01-16, id=16}
              {name=何苗, birth=2014-01-17, id=18}
              {name=芳芳, birth=1996-03-04, id=19}
             */
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCUtilsC3P0.closeResource(conn, null, null);
        }
    }

    //
    // ScalarHandler是ResultSetHandler接口的实现类， 用于查询特殊值
    //返回表中的记录数
    @Test
    public void testQuery5() throws Exception {
        Connection conn = null;
        try {
            QueryRunner runner = new QueryRunner();
            conn = JDBCUtilsC3P0.getConnection();
            String sql = "select count(*) from customers";
            ScalarHandler handler = new ScalarHandler();
            Long count = (Long) runner.query(conn, sql, handler);
            System.out.println(count);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCUtilsC3P0.closeResource(conn, null, null);
        }
    }
    // ScalarHandler是ResultSetHandler接口的实现类，
    //返回表中的最大出生日期
    @Test
    public void testQuery6() throws Exception {
        Connection conn = null;
        try {
            QueryRunner runner = new QueryRunner();
            conn = JDBCUtilsC3P0.getConnection();
            String sql = "select max(birth) from customers";
            ScalarHandler handler = new ScalarHandler();
            Date maxBirth = (Date) runner.query(conn, sql, handler);
            System.out.println(maxBirth);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCUtilsC3P0.closeResource(conn, null, null);
        }
    }
}

使用Dbutils关闭资源

例如：

JDBCUtilsC3P0

package com.aff.util;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.apache.commons.dbutils.DbUtils;

import com.mchange.v2.c3p0.ComboPooledDataSource;

//使用C3P0数据库连接池
public class JDBCUtilsC3P0 {
    // 把池子拿到外边，连接池一个就够，需要的连接从池子中拿
    private static ComboPooledDataSource cbpds = new ComboPooledDataSource("helloc3p0");

    public static Connection getConnection() throws SQLException {
        Connection conn = cbpds.getConnection();
        return conn;
    }
    public static void closeResource(Connection conn, PreparedStatement ps, ResultSet rs) {
        // 7.资源的关闭
        DbUtils.closeQuietly(conn);
        DbUtils.closeQuietly(ps);
        DbUtils.closeQuietly(rs);
    }
}