Spring 数据源配置与应用

Spring对数据库操作都依赖数据源。

Spring有默认的数据源实现
org.springframework.jdbc.datasource.DriverManagerDataSource，但也可以配置其他的数据源
实现，比如DBCP的数据源public class BasicDataSource implements
javax.sql.DataSource。

一旦获取到数据源DataSource实例，就可以通过DataSource获取到数据库连接，操作数据库。

下面是Spring数据源的一个简单配置和应用。
应用环境：MySQL5

drop table if exists user;

/*==============================================================*/
/* Table: user */
/*==============================================================*/
create table user
(
id bigint AUTO_INCREMENT not null,
name varchar(24),
age int,
primary key (id)
);

public class User {
private Integer id;
private String name;
private Integer age;

public Integer getId() {
return id;
}

public void setId(Integer id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public Integer getAge() {
return age;
}

public void setAge(Integer age) {
this.age = age;
}
}

public interface IUserDAO {
public void insert(User user);

public User find(Integer id);
}

/**
* Created by IntelliJ IDEA.<br>
* <b>User</b>: leizhimin<br>
* <b>Date</b>: 2008-4-22 11:40:18<br>
* <b>Note</b>: 子类DAO
*/
public class UserDAO extends BaseDAO implements IUserDAO {
public void insert(User user) {
String name = user.getName();
int age = user.getAge().intValue();

Connection conn = null;
Statement stmt = null;

try {
conn = getConnection();
stmt = conn.createStatement();
stmt.execute("INSERT INTO user (name,age) " + "VALUES('" + name + "'," + age + ")");
} catch (SQLException e) {
e.printStackTrace();
}
finally {
if (stmt != null) {
try {
stmt.close();
}
catch (SQLException e) {
e.printStackTrace();
}
}
if (conn != null) {
try {
conn.close();
}
catch (SQLException e) {
e.printStackTrace();
}
}
}
}

public User find(Integer id) {
Connection conn = null;
Statement stmt = null;

try {
conn = getConnection();
stmt = conn.createStatement();

ResultSet result = stmt.executeQuery(
"SELECT * FROM user WHERE id=" + id.intValue());
if (result.next()) {
Integer i = new Integer(result.getInt(1));
String name = result.getString(2);
Integer age = new Integer(result.getInt(3));

User user = new User();
user.setId(i);
user.setName(name);
user.setAge(age);

return user;
}
} catch (SQLException e) {
e.printStackTrace();
}
finally {
if (stmt != null) {
try {
stmt.close();
}
catch (SQLException e) {
e.printStackTrace();
}
}
if (conn != null) {
try {
conn.close();
}
catch (SQLException e) {
e.printStackTrace();
}
}
}

return null;
}
}

/**
* Created by IntelliJ IDEA.<br>
* <b>User</b>: leizhimin<br>
* <b>Date</b>: 2008-4-22 13:53:56<br>
* <b>Note</b>: 基类DAO，提供了数据源注入
*/
public class BaseDAO {
private DataSource dataSource;

public DataSource getDataSource() {
return dataSource;
}

public void setDataSource(DataSource dataSource) {
this.dataSource = dataSource;
}

public Connection getConnection() {
Connection conn = null;
try {
conn = dataSource.getConnection();
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}
}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING/DTD BEAN/EN"
"http://www.springframework.org/dtd/spring-beans.dtd">

<beans>
<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName">
<value>com.mysql.jdbc.Driver</value>
</property>
<property name="url">
<value>jdbc:mysql://localhost:3306/springdb</value>
</property>
<property name="username">
<value>root</value>
</property>
<property name="password">
<value>leizhimin</value>
</property>
</bean>

<bean id="baseDAO" class="com.lavasoft.springnote.ch05_jdbc02.BaseDAO" abstract="true">
<property name="dataSource">
<ref bean="dataSource"/>
</property>
</bean>

<bean id="userDAO"
class="com.lavasoft.springnote.ch05_jdbc02.UserDAO" parent="baseDAO">
</bean>
</beans>

/**
* Created by IntelliJ IDEA.<br>
* <b>User</b>: leizhimin<br>
* <b>Date</b>: 2008-4-22 11:41:34<br>
* <b>Note</b>: 客户端测试
*/
public class SpringDAODemo {
public static void main(String[] args) {
ApplicationContext context = new FileSystemXmlApplicationContext("D://_spring//src//com//lavasoft//springnote//ch05_jdbc02//bean-jdbc.xml");
User user = new User();
user.setName("caterpillar");
user.setAge(new Integer(30));
IUserDAO userDAO = (IUserDAO) context.getBean("userDAO");
userDAO.insert(user);
user = userDAO.find(new Integer(1));
System.out.println("name: " + user.getName());
}
}

运行结果：

log4j:WARN No appenders could be found for logger (org.springframework.core.CollectionFactory).
log4j:WARN Please initialize the log4j system properly.
name: jdbctemplate

Process finished with exit code 0

注意：Spring配置文件中对继承的配置，DataSource注入方式，通过继承来注入，从而简化编程。

上面用的是Spring的自己的数据源实现，现在假如要换成apache的DBCP数据源，则配置改为如下即可：

<bean id="dataSource"
class="org.apache.commons.dbcp.BasicDataSource" singleton="true">
<property name="driverClassName">
<value>com.mysql.jdbc.Driver</value>
</property>
<property name="url">
<value>jdbc:mysql://localhost:3306/springdb</value>
</property>
<property name="username">
<value>root</value>
</property>
<property name="password">
<value>leizhimin</value>
</property>
</bean>

实际上仅仅是更改一下数据源的calss实现。

本文出自 “熔 岩” 博客