DBUtils Tool Notes [Simple]

Introduction to DBUtils

Commons DbUtils is an open source tool class library provided by the Apache organization that simply encapsulates JDBC . Using it can simplify the development of JDBC applications without affecting the performance of the program.

DBUtis的API

    QueryRunner class: execute sql statement
    ResultSetHandler interface: encapsulate the result set into a bean
    DBUtils class: tool class closes resource transaction related

Quick Start (Small Case)

Create a user table

create table user(
id varchar(50) primary key,
name varchar(20),
age int,
addr varchar(255),
idcard varchar(20),
account int);

Original jdbc way:

Using DBUtils way:

QueryRunner details

How QueryRunner is created
    QueryRunner runner = new QueryRunner();//Manual transaction
    QueryRunner runner = new QueryRunner(DataSource);// There are three methods of automatic transaction
QueryRunner :             update() batch() query()

update method

Parameters:
    Connection: connection object
    sql: sql statement (must have)
    params: the value of the placeholder position in the sql statement
Method of composition:
        update(Connection,sql,params): To manually control the transaction sql, you need to pass in the parameter
        update(Connection ,sql): Manually control transaction sql without parameters For example: delete from user;
        update(sql,params): Automatically control transaction sql requires parameters
        update(sql): Automatically control transaction sql does not require parameters

Automatic transaction execution update

Manual transaction execution update

batch method -- batch

Parameters:
    Connection: connection object
    sql: sql statement (must have)
    params: the value of the placeholder position in the sql statement Two-dimensional array
Method of composition:
    batch(Connection,sql,params): all batches if the transaction is rolled back The sql does not take effect
    batch(sql,params)

Automatic transaction execution batch

Manual transaction execution batch

query method

Parameters:
    Connection: connection object
    sql: sql statement (must have)
    params: the value of the placeholder position in the sql statement 2D array
    ResultSetHandler: encapsulated result set (must have)
Composition method:
    query(connection,sql,params,resultsetHandler )
    query(connection,sql,resultsetHandler)
    query(sql,params,resultsetHandler)
    query(sql,resultsetHandler)

ResultSetHandler: encapsulates the result set

handle方法（ResultSet）

custom generic handler

DBUtils provides implementations of 9 ResultSetHandler interfaces

BeanListHandler : The return is a list list encapsulated in entity beans

BeanHandler : The return is the entity bean

ArrayHandler: The return value is an array

ArrayListHandler: The return value is List<Object[]> Each row of data in the result set is encapsulated into an array, and multiple data are put into the collection