一 简介
Commons DbUtils是Apache组织提供的一个对JDBC进行简单封装的开源工具类库，使用它能够简化JDBC应用程序的开发，同时也不会影响程序的性能。
下载组件，引入jar文件：commons-dbutils-1.6.jar
maven配置：
<dependency>
<groupId>commons-dbutils</groupId>
<artifactId>commons-dbutils</artifactId>
<version>1.6</version>
</dependency>
二 核心类QueryRunner
-
带有Connection的
- Int update(Connection conn, String sql, Object param);执行更新带一个占位符的sql
- Int update(Connection conn, String sql, Object… param);执行更新带多个占位符的sql
- Int[] batch(Connection conn, String sql, Object[][] params) 批处理
- T query(Connection conn ,String sql, ResultSetHandler<T> rsh, Object... params) 查询方法
-
不带有Connection的
- Int update( String sql, Object param); 执行更新带一个占位符的sql
- Int update( String sql, Object… param);执行更新带多个占位符的sql
- Int[] batch( String sql, Object[][] params); 批处理
注意： 如果调用DbUtils组件的操作数据库方法，没有传入连接对象，那么在实例化QueryRunner对象的时候需要传入数据源对象：
QueryRunner qr = new QueryRunner(DataSource ds);
三 更新操作（包括delete 、insert、 update）
1 删除
package Dao;
import org.apache.commons.dbutils.QueryRunner;
import utils.jdbcUtil;
import java.sql.*;
/**
* Created by pc on 2017/9/9.
*/
public class DbUtils {
public static void main(String [] args){
try {
String sql = " delete from student where id =? ";
Connection conn = jdbcUtil.getConnection();
QueryRunner queryRunner= new QueryRunner();
queryRunner.update(conn,sql,7);
jdbcUtil.close(conn,null,null);
}catch (Exception e){
throw new RuntimeException(e);
}
}
}
7已删除
2 插入
方法一
package Dao;
import org.apache.commons.dbutils.QueryRunner;
import utils.jdbcUtil;
import java.sql.*;
public class DbUtils {
public static void main(String [] args){
try {
String sql = "INSERT INTO student (NAME,PASSWORD) VALUE (?,?)";
Connection conn = jdbcUtil.getConnection();
QueryRunner queryRunner= new QueryRunner();
queryRunner.update(conn,sql,"丹丹",123456);
jdbcUtil.close(conn,null,null);
}catch (Exception e){
throw new RuntimeException(e);
}
}
}
结果显示
方法二
package Dao;
import org.apache.commons.dbutils.QueryRunner;
import utils.jdbcUtil;
import java.sql.*;
/**
* Created by pc on 2017/9/9.
*/
public class DbUtils {
public static void main(String [] args){
try {
String sql = "INSERT INTO student (NAME,PASSWORD) VALUE (?,?)";
Connection conn = jdbcUtil.getConnection();
QueryRunner queryRunner= new QueryRunner();
queryRunner.batch(conn,sql,new Object[][]{{"李彦斌",666666},{"胡歌",888888}});
jdbcUtil.close(conn,null,null);
}catch (Exception e){
throw new RuntimeException(e);
}
}
}
结果显示
四 查询操作
DbUtils提供的封装结果的一些对象：
- BeanHandler: 查询返回单个对象
- BeanListHandler: 查询返回list集合，集合元素是指定的对象
- ArrayHandler, 查询返回结果记录的第一行，封装对对象数组, 即返回：Object[]
- ArrayListHandler, 把查询的每一行都封装为对象数组，再添加到list集合中
- ScalarHandler 查询返回结果记录的第一行的第一列 (在聚合函数统计的时候用)
- MapHandler 查询返回结果的第一条记录封装为map
- MapListHandler 查询返回结果封装为List<map>
1 自定义结果集封装数据
package Dao;
import entity.Student;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.ResultSetHandler;
import utils.jdbcUtil;
import java.sql.*;
/**
* Created by pc on 2017/9/9.
*/
public class DbUtils {
public static void main(String [] args) throws Exception{
final String sql = "select * from student where id = ?";
Connection conn =jdbcUtil.getConnection();
QueryRunner qr = new QueryRunner();
//查询
final Student student = qr.query(conn, sql, new ResultSetHandler<Student>() {
//自定义 封装一个Bean对象
public Student handle(ResultSet resultSet) throws SQLException {
if (resultSet.next()){
Student student1 = new Student();
student1.setId(resultSet.getInt("id"));
student1.setName(resultSet.getString("name"));
student1.setPassword(resultSet.getInt("password"));
return student1;
}
return null;
}
},1);
System.out.println(student.getId()+student.getName()+student.getPassword());
}
}
结果显示
2 查询使用组件提供的BeanHandler结果集对象封装数据
package Dao;
import entity.Student;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.ResultSetHandler;
import org.apache.commons.dbutils.handlers.BeanHandler;
import utils.jdbcUtil;
import java.sql.*;
/**
* Created by pc on 2017/9/9.
*/
public class DbUtils {
public static void main(String [] args) throws Exception{
final String sql = "select * from student where id = ?";
Connection conn =jdbcUtil.getConnection();
QueryRunner qr = new QueryRunner();
Student student = qr.query(conn,sql,new BeanHandler<Student>(Student.class),2);
System.out.println(student.getId()+student.getName()+student.getPassword());
conn.close();
}
}
结果显示
3 查询使用组件提供的BeanListHandler结果集对象封装数据
package Dao;
import entity.Student;
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 utils.jdbcUtil;
import java.sql.*;
import java.util.List;
public class DbUtils {
public static void main(String [] args) throws Exception{
final String sql = "select * from student where id = ?";
Connection conn =jdbcUtil.getConnection();
QueryRunner qr = new QueryRunner();
List<Student> student = qr.query(conn,sql,new BeanListHandler<Student>(Student.class),3);
System.out.println(student.get(0).getId()+student.get(0).getName()+student.get(0).getPassword());
conn.close();
}
}
运行结果
4 查询使用组件提供的MapHandler 结果集对象封装数据
package Dao;
import entity.Student;
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 utils.jdbcUtil;
import java.sql.*;
import java.util.List;
import java.util.Map;
public class DbUtils {
public static void main(String [] args) throws Exception{
final String sql = "select * from student";
Connection conn =jdbcUtil.getConnection();
QueryRunner qr = new QueryRunner();
Map<String,Object> stuent = qr.query(conn,sql,new MapHandler());
System.out.println(stuent);
conn.close();
}
}
运行结果
5 查询使用组件提供的ScalarHandler 结果集对象封装数据(在聚合函数统计时候用)
package Dao;
import entity.Student;
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.ScalarHandler;
import utils.jdbcUtil;
import java.sql.*;
import java.util.List;
import java.util.Map;
public class DbUtils {
public static void main(String [] args) throws Exception{
final String sql = "select count(*) from student";
Connection conn =jdbcUtil.getConnection();
QueryRunner qr = new QueryRunner();
Long stuent = qr.query(conn,sql,new ScalarHandler<Long>());
System.out.println(stuent);
conn.close();
}
}
运行结果
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