spring注入的四种方式

配置文件spring.xml:

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"

xmlns:tx="http://www.springframework.org/schema/tx"

xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd

           http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd

           http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">

<!-- 注入方式一，直接使用类全名注入，属性必须有相应的set方法才可以注入成功，否则会失败 -->

<!-- 假如没有a属性，但是有setA方法，也可以配置a的property和value，但这样做并没有什么意义 -->

<bean id="userDao1" class="com.colorlight.spring.UserDaoImpl">

<property name="jdbcUrl" value="jdbc:mysql://localhost:3306/test"></property>

<property name="driverClass" value="com.mysql.jdbc.Driver"></property>

<property name="username" value="root"></property>

<property name="password" value="1"></property>

</bean>

<!-- 注入方式二：使用静态的工厂方法创建实例，必须配置相应的工厂类和工厂方法 -->

<bean id="userDao2" class="com.colorlight.spring.StaticDaoFactory"

factory-method="createUserDaoInstance">

<property name="jdbcUrl" value="jdbc:mysql://localhost:3306/test"></property>

<property name="driverClass" value="com.mysql.jdbc.Driver"></property>

<property name="username" value="root"></property>

<property name="password" value="2"></property>

</bean>

<!-- 注入方式三：使用非静态的工厂方法创建实例，必须先生成工厂的实例 -->

<bean id="daoFactory" class="com.colorlight.spring.NonStaticDaoFactory">

</bean>

<bean id="userDao3" factory-bean="daoFactory" factory-method="createUserDao">

<property name="jdbcUrl" value="jdbc:mysql://localhost:3306/test"></property>

<property name="driverClass" value="com.mysql.jdbc.Driver"></property>

<property name="username" value="root"></property>

<property name="password" value="3"></property>

</bean>

<!-- 注入方式四：使用构造函数注入 -->

<bean id="userDao4" class="com.colorlight.spring.UserDaoImpl">

<constructor-arg value="jdbc:mysql://localhost:3306/test" />

<constructor-arg value="com.mysql.jdbc.Driver" />

<constructor-arg value="root" />

<constructor-arg value="4" />

</bean>

</beans>

接口UserDao:

package com.colorlight.spring;

public interface UserDao {

void printInfo();

}

实现类UserDaoImpl：

package com.colorlight.spring;

public class UserDaoImpl implements UserDao {

private String jdbcUrl;

private String driverClass;

private String username;

private String password;

public UserDaoImpl(){

}

public UserDaoImpl(String url, String driver, String name, String pw) {

this.jdbcUrl = url;

this.driverClass = driver;

this.username = name;

this.password = pw;

}

public void printInfo() {

System.out.println("jdbcUrl  = " + jdbcUrl);

System.out.println("driverClass = " + driverClass);

System.out.println("username = " + username);

System.out.println("password = " + password);

}

public String getJdbcUrl() {

return jdbcUrl;

}

public void setJdbcUrl(String jdbcUrl) {

this.jdbcUrl = jdbcUrl;

}

public String getDriverClass() {

return driverClass;

}

public void setDriverClass(String driverClass) {

this.driverClass = driverClass;

}

public String getUsername() {

return username;

}

public void setUsername(String username) {

this.username = username;

}

public String getPassword() {

return password;

}

public void setPassword(String password) {

this.password = password;

}

}

静态方法类：

package com.colorlight.spring;

public class StaticDaoFactory {

public static UserDao createUserDaoInstance(){

return new UserDaoImpl();

}

}

非静态方法类：

package com.colorlight.spring;

public class NonStaticDaoFactory {

public UserDao createUserDao() {

return new UserDaoImpl();

}

}

测试类：

package com.colorlight.springscope;

import org.junit.Test;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MainTest {

ApplicationContext ac = new ClassPathXmlApplicationContext(

"applicationContext.xml", this.getClass());

// 单例

@Test

public void test1() {

System.out.println("在getBean()调用之前");

User user1 = (User) ac.getBean("user1");

User user2 = (User) ac.getBean("user1");

System.out.println(user1 != null);

System.out.println(user1 == user2);

}

// 多例

@Test

public void test2() {

System.out.println("在getBean()调用之前");

User user1 = (User) ac.getBean("user2");

User user2 = (User) ac.getBean("user2");

System.out.println(user1 != null);

System.out.println(user1 == user2);

}

}