Dbutils Essentials Summary

I. Dbutils Core API

1. Queryrunner

Update method

Query method

2. All kinds of handler implement Resultsethandler interface

Beanhandler

Beanlisthandler

Beanmaphandler

Arrayhandler

Arraylisthandler

Maplisthandler

Scalarhandler

Columnlisthandler

Keyedhandler

Two. Handler hierarchy

Generating class diagrams using idea

Three. Queryrunner Query for Entities

Dbutils principle: Perform sql-> return resultset-> reflection Create entity Object->handler

Benefit: No need to face pstmt and RS objects

Four. Using threadlocal to achieve con transparency

Threadlocal is a container for isolating threads

Specific operation:

1) When you get con, look in the TL container

2) When the con is created, it is stored in the TL container

3) After the con is used, remove from the TL container and the TL container will be destroyed when the thread ends.

Five. Using connection pooling

Frequent creation of con objects results in significant overhead and a limited number of connections to the database, which can be pooled using the DPCP connection pool

Six. A picture to understand Maplisthandler

Report:

Add DPCP dependency in Pom.xml

1 <Dependency>2     <groupId>Org.apache.commons</groupId>3     <Artifactid>Commons-dbcp2</Artifactid>4     <version>2.0.1</version>5 </Dependency>

Pom.xml adding dbutils dependencies

1 <Dependency>2     <groupId>Commons-beanutils</groupId>3     <Artifactid>Commons-beanutils</Artifactid>4     <version>1.6</version>5 </Dependency>

Dbutils Essentials Summary