Spring 数据源配置与应用

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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 implementsjavax.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. 
* User: leizhimin 
* Date: 2008-4-22 11:40:18 
* Note: 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. 
* User: leizhimin 
* Date: 2008-4-22 13:53:56 
* Note: 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. 
* User: leizhimin 
* Date: 2008-4-22 11:41:34 
* Note: 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。

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