标签：rtb let 技术 data 处理 ide 并且 test dha
commons-dbutils 是 Apache 组织提供的一个开源 JDBC工具类库，它是对JDBC的简单封装，学习成本极低，并且使用dbutils能极大简化jdbc编码的工作量，同时也不会影响程序的性能。
API包说明：
该类简单化了SQL查询，它与ResultSetHandler组合在一起使用可以完成大部分的数据库操作，能够大大减少编码量。
测试
// 测试添加
@Test
public void testInsert() throws Exception {
QueryRunner runner = new QueryRunner();
Connection conn = JDBCUtils.getConnection3();
String sql = "insert into customers(name,email,birth)values(?,?,?)";
int count = runner.update(conn, sql, "何成飞", "he@qq.com", "1992-09-08");
System.out.println("添加了" + count + "条记录");
JDBCUtils.closeResource(conn, null);
}// 测试删除
@Test
public void testDelete() throws Exception {
QueryRunner runner = new QueryRunner();
Connection conn = JDBCUtils.getConnection3();
String sql = "delete from customers where id < ?";
int count = runner.update(conn, sql,3);
System.out.println("删除了" + count + "条记录");
JDBCUtils.closeResource(conn, null);
}该接口用于处理 java.sql.ResultSet，将数据按要求转换为另一种形式。
ResultSetHandler 接口提供了一个单独的方法：Object handle (java.sql.ResultSet .rs)。
接口的主要实现类：
测试
/*
* 测试查询:查询一条记录
*
* 使用ResultSetHandler的实现类：BeanHandler
*/
@Test
public void testQueryInstance() throws Exception{
QueryRunner runner = new QueryRunner();
Connection 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);
JDBCUtils.closeResource(conn, null);
}/*
* 测试查询:查询多条记录构成的集合
*
* 使用ResultSetHandler的实现类：BeanListHandler
*/
@Test
public void testQueryList() throws Exception{
QueryRunner runner = new QueryRunner();
Connection 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);
JDBCUtils.closeResource(conn, null);
}/*
* 自定义ResultSetHandler的实现类
*/
@Test
public void testQueryInstance1() throws Exception{
QueryRunner runner = new QueryRunner();
Connection 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 new Customer(1,"Tom","tom@126.com",new Date(123323432L));
if(rs.next()){
int id = rs.getInt("id");
String name = rs.getString("name");
String email = rs.getString("email");
Date birth = rs.getDate("birth");
return new Customer(id, name, email, birth);
}
return null;
}
};
Customer customer = runner.query(conn, sql, handler, 23);
System.out.println(customer);
JDBCUtils.closeResource(conn, null);
}/*
* 如何查询类似于最大的，最小的，平均的，总和，个数相关的数据，
* 使用ScalarHandler
*
*/
@Test
public void testQueryValue() throws Exception{
QueryRunner runner = new QueryRunner();
Connection conn = JDBCUtils.getConnection3();
//测试一：
// String sql = "select count(*) from customers where id < ?";
// ScalarHandler handler = new ScalarHandler();
// long count = (long) runner.query(conn, sql, handler, 20);
// System.out.println(count);
//测试二：
String sql = "select max(birth) from customers";
ScalarHandler handler = new ScalarHandler();
Date birth = (Date) runner.query(conn, sql, handler);
System.out.println(birth);
JDBCUtils.closeResource(conn, null);
}JAVA JDBC Apache-DBUtils实现CRUD操作
标签：rtb let 技术 data 处理 ide 并且 test dha
原文地址：https://www.cnblogs.com/superxuezhazha/p/12433138.html
