# DBCP

## DBCP(DataBase Connection Pool)

## 의존성 설정

이 문서에서는 [apache common dbcp](https://commons.apache.org/proper/commons-dbcp/download_dbcp.cgi)를 사용할 것이기 때문에 pom.xml에 maven 저장소에서 `apache dbcp2` 를 검색한 결과를 추가한다.

### pom.xml

```xml
<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-dbcp2</artifactId>
    <version>2.7.0</version>
</dependency>
```

데이터베이스 연결을 위해 필요한 의존성도 추가해야한다. [JDBC](http://www.sysout.co.kr/home/webbook/page/spring12jdbc) 문서를 참고.

## Spring Bean 등록

### DataSource 설정

`Apache Common DBCP`를 이용하기 위해서는 `DataSource`를 `org.apache.commons.dbcp2.BasicDataSource`로 등록해야 한다.

### src/main/webapp/WEB-INF/spring/root-context.xml

```xml
<bean id="dataSource" class="org.apache.commons.dbcp2.BasicDataSource">
	<property name="driverClassName" value="oracle.jdbc.OracleDriver"></property>
	<property name="url" value="jdbc:oracle:thin:@localhost:1521:xe"></property>
	<property name="username" value="test"></property>
	<property name="password" value="test"></property>
	
	<property name="maxTotal" value="20"></property>
	<property name="maxIdle" value="10"></property>
	<property name="maxWaitMillis" value="3000"></property>
</bean>
```

기존의 JDBC에서 설정한 `DriverManagerDataSource`와 비교하기 위해 코드를 살펴보면 다음과 같다.

```xml
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
	<property name="driverClassName" value="oracle.jdbc.OracleDriver"></property>
	<property name="url" value="jdbc:oracle:thin:@localhost:1521:xe"></property>
	<property name="username" value="test"></property>
	<property name="password" value="test"></property>
</bean>
```

추가된 항목은 다음과 같다.

* maxTotal : 유지할 Connection Pool의 최대 크기
* maxIdle : 유지할 Connection Pool 내부의 유휴 연결 개수
* maxWaitMillis : Connection Pool의 모든 연결이 사용중일 때의 대기시간(ms)

### JdbcTemplate 설정

생성한 `dataSource`를 `JdbcTemplate`에 설정한다.

```xml
<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
	<property name="dataSource" ref="dataSource"></property>
</bean>
```

## Test 수행

다른 코드들은 기존의 JDBC와 다르지 않기 때문에 select 구문만 수행하여 연결이 정상적으로 이루어지는지 확인한다.

> src/test/java : com.hakademy.spring13.Test01

```java
package com.hakademy.spring13;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.test.context.web.WebAppConfiguration;

@RunWith(SpringJUnit4ClassRunner.class)
@WebAppConfiguration
@ContextConfiguration(locations = {
	"file:src/main/webapp/WEB-INF/spring/root-context.xml",
	"file:src/main/webapp/WEB-INF/spring/appServlet/servlet-context.xml"
})
public class Test01 {

	@Autowired
	private JdbcTemplate jdbcTemplate;
	
	@Test
	public void selectCount() {
		String sql = "select count(*) from student";
		int count = jdbcTemplate.queryForObject(sql, Integer.class);
		System.out.println("count = "+count);
	}
	
}
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.sysout.co.kr/web/back-end/what-is-spring-framework/spring-jdbc/dbcp.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.