Spring学习笔记（一）

Spring学习笔记（一）

Spring核心思想：

IOC:  Inversion Of Control (控制反转) / DI: Dependency Injection (依赖注入)

AOP: Aspect Oriented Programming (面向切面编程)

IOC

1. 简单的应用

Model

package com.wangj.spring.model;

public class User {
    private String username;
    private String password;

    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;
    }
}

Dao

package com.wangj.spring.dao;

import com.wangj.spring.model.User;

public interface UserDao {
    void save(User user);
}

DaoImpl

package com.wangj.spring.dao.impl;

import com.wangj.spring.dao.UserDao;
import com.wangj.spring.model.User;

public class UserDaoImpl implements UserDao {
    @Override
    public void save(User user) {
        System.out.println(String.format("user(%s) saved!", user.getUsername()));
    }
}

Service

package com.wangj.spring.service;

import com.wangj.spring.dao.UserDao;
import com.wangj.spring.model.User;

public class UserService {
    private UserDao userDao;

    public void add(User user) {
        userDao.save(user);
    }

    public UserDao getUserDao() {
        return userDao;
    }

    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }
}

jar

applicationContext.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:aop="http://www.springframework.org/schema/aop"
    xmlns:p="http://www.springframework.org/schema/p" 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.xsd
            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
            http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
            http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">

    <bean id="userDao" class="com.wangj.spring.dao.impl.UserDaoImpl">
    </bean>

    <bean id="userService" class="com.wangj.spring.service.UserService">
        <property name="userDao" ref="userDao"></property>
    </bean>
</beans>

test

package com.wangj.spring;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;

import com.wangj.spring.model.User;
import com.wangj.spring.service.UserService;

public class SpringDemo {
    public static void main(String[] args) {
        ApplicationContext applicationContext = new FileSystemXmlApplicationContext("config/applicationContext.xml");

        UserService service = (UserService) applicationContext.getBean("userService");

        User user = new User();
        user.setUsername("wangj");
        user.setPassword("wangj1130");
        service.add(user);
    }
}

2. 具体用法（XML配置）

• bean注入方法

1. set方法注入

<bean id="userService" class="com.wangj.spring.service.UserService">
    <property name="userDao" ref="userDao"></property>
</bean>

2. 构造方法注入
<bean id="userService" class="com.wangj.spring.service.UserService">
<constructor-arg>
    <ref bean="userDao"/>
    <!-- <bean class="com.wangj.test.spring.dao.impl.UserDaoImpl"/> --> <!-- 重新new对象 -->
</constructor-arg>
</bean>

当构造方法里含有多个参数时：
1）根据类型
<bean id="exampleBean" class="examples.ExampleBean">
    <constructor-arg type="int" value="7500000"/>
    <constructor-arg type="java.lang.String" value="42"/>
</bean>
2）根据顺序
<bean id="exampleBean" class="examples.ExampleBean">
    <constructor-arg index="0" value="7500000"/>
    <constructor-arg index="1" value="42"/>
</bean>

• bean scope属性：

　　scope="singleton" //(默认)每次使用同一个对象

　　　　　="prototype" //每次都new一个新的（Struts Action）

　　　　　=request、session、global session（不重要）

• 集合注入

<bean name="userDAO" class="com.wangj.dao.impl.UserDAOImpl">
      <property name="sets">
          <set>
              <value>1</value>
              <value>2</value>
          </set>
      </property>
      <property name="lists">
          <list>
              <value>1</value>
              <value>2</value>
              <value>3</value>
          </list>
      </property>
      <property name="maps">
          <map>
              <entry key="1" value="1"></entry>
              <entry key="2" value="2"></entry>
              <entry key="3" value="3"></entry>
              <entry key="4" value="4"></entry>
          </map>
      </property>
</bean>

• autowire 自动装配

　　autowire="byName" // 根据名称自动装配，该名称为setXxx()方法中xxx(set后的字符串首字母小写)，与变量名无关

　　　　　　="byType" // 根据类型自动装配

　　　　　　="default" // 跟<beans 节点中 default-autowire属性一致，如果<beans节点中未配置default-autowire属性，则报异常

• bean生命周期

　　lazy-init="true" // 什么时用到什么时候初始化（sping初始化默认将所有bean加载到内存）

　　init-method="init" // 容器初始化时调用

　　destroy-method="destroy" // 容器销毁时调用

　　(init-method、destroy-method 一般不和prototype一起用)