Spring
Spring的优势
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方便解耦,简化开发
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AOP编程支持
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声明式事务的支持 统一事务管理
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方便程序的测试
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方便继承各种优秀的框架
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降低JavaEE API的使用难度 工具模板
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Java 源码是经典学习范例
Spring程序开发步骤
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导入Spring 开发的基本包坐标
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编写Dao接口和实现类
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创建Spring核心配置文件
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在Spring配置文件中配置UserDaoImpl
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实现Spring的API获取Bean实例
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>5.2.11.RELEASE</version>
</dependency>
</dependencies>
package com.cyz.dao;
public interface UserDao {
public void save();
}
package com.cyz.dao.impl;
import com.cyz.dao.UserDao;
public class UserDaoImpl implements UserDao {
-
applicationContext.xml
package com.cyz.demo;
import com.cyz.dao.UserDao;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class UserDaoDemo {
public static void main(String[] args) {
ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
UserDao userDao = (UserDao)app.getBean("userDao");
userDao.save();
}
}
Spring配置文件
Bean标签基本配置
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用于配置对象交由Sprng来创建
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默认情况下他调用的是类中的无参构造函数,如果没有无参构造函数则不能创建成功
基本属性
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id: Bean示例在Spring容器中的唯一标识
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class:Bean的全限定名称
Bean标签范围配置
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scope: 指对象的作用范围,取值如下:
取值返回 | 说明 |
---|---|
singleton | 默认值,单例的 |
prototype | 多例的 |
request | Web项目中,Spring创建一个Bean的对象,将对象存入到request域中 |
session | Web项目中,Spring创建一个Bean的对象,将对象存入到request域中 |
global session | Web项目中,应用在Portlet环境,如果没有Protlet环境那么globalSession相当于session |
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13</version>
</dependency>
package com.cyz.test;
import com.cyz.dao.UserDao;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class SpringTest {
测试无参构造
package com.cyz.dao.impl;
import com.cyz.dao.UserDao;
public class UserDaoImpl implements UserDao {
public UserDaoImpl(){
System.out.println("UserDaoImpl无参构造。。。。");
}
1) 当scope的取值是singleton时
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Bean 的实例化个数:1个
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Bean的实例化实机:当Spring核心文件加载时,实例化配置的Bean实例
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Bean的生命周期
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对象创建: 当应用加载,创建容器时,对象就被创建了
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对象运行:只要容器在,对象一直活着
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对象销毁:当应用卸载,摧毁容器时,对象就被销毁了
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1) 当scope的取值是prototype时
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Bean 的实例化个数:多个
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Bean的实例化实机:当调用getBean()方法时实例化Bean
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Bean的生命周期
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对象创建: 当使用对象时,创建新的对象实例
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对象运行:只要对象在使用中,就一直活着
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对象销毁:当对象长时间不用时,被Java的垃圾回收器回收了
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Bean的生命周期配置
配置对象初始化方法和销毁方法
package com.cyz.dao.impl;
import com.cyz.dao.UserDao;
public class UserDaoImpl implements UserDao {
public UserDaoImpl(){
System.out.println("UserDaoImpl无参构造。。。。");
}
public void init(){
System.out.println("初始化方法。。。。");
}
public void destory(){
System.out.println("销毁方法。。。。");
}
package com.cyz.test;
import com.cyz.dao.UserDao;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
// 注意使用的是 ClassPathXmlApplicationContext
// 调用close() 手动关闭容器才看到 自动销毁太快了看不到
public class SpringTest {
Bean实例化方式(三种)
无参构造实例化
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默认使用
工厂静态方法实例化
package com.cyz.factory;
import com.cyz.dao.UserDao;
import com.cyz.dao.impl.UserDaoImpl;
public class StaticFactory {
public static UserDao getUserDao(){
return new UserDaoImpl();
}
}
工程实例方法实例化
package com.cyz.factory;
import com.cyz.dao.UserDao;
import com.cyz.dao.impl.UserDaoImpl;
public class DynamicFactory {
public UserDao getUserDao(){
return new UserDaoImpl();
}
}
依赖注入
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分析
package com.cyz.service;
public interface UserService {
public void save();
}
package com.cyz.service.impl;
import com.cyz.dao.UserDao;
import com.cyz.service.UserService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class UserServiceImpl implements UserService {
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模拟
package com.cyz.demo;
import com.cyz.service.UserService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class UserCon troller {
public static void main(String[] args) {
ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
UserService userService = (UserService)app.getBean("userService");
userService.save();
}
}
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方式是不合理的 需要在容器内部进行注入
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实现方式:
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set
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构造方法
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概念
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依赖注入是Spring框架核心IOC的具体实现
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在编写程序时,通过控制反转,把对象的创建交给Spring,但是代码中不可能出现没有依赖的情况
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IOC解耦只是降低他们的依赖关系,但不会消除,例如: 业务层仍会调用持久层的方法
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业务层和持久层交由Spring管理维护,坐等框架把持久层对象传入业务层,而不用自己去获取
Set方法注入
package com.cyz.service.impl;
import com.cyz.dao.UserDao;
import com.cyz.service.UserService;
public class UserServiceImpl implements UserService {
private UserDao userDao;
public void setUserDao(UserDao userDao) {
this.userDao = userDao;
}
package com.cyz.demo;
import com.cyz.service.UserService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class UserController {
public static void main(String[] args) {
ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
UserService userService = (UserService)app.getBean("userService");
userService.save();
}
}
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注意自己new 的bean拿不到useDao
package com.cyz.demo;
import com.cyz.dao.UserDao;
import com.cyz.service.UserService;
import com.cyz.service.impl.UserServiceImpl;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class UserController {
public static void main(String[] args) {
// ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
// UserService userService = (UserService)app.getBean("userService");
// userService.save();
UserService userService = new UserServiceImpl();
userService.save();
}
}
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p命名空间简化set注入
xmlns:p="http://www.springframework.org/schema/p"
构造方法注入
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有参构造
package com.cyz.service.impl;
import com.cyz.dao.UserDao;
import com.cyz.service.UserService;
public class UserServiceImpl implements UserService {
private UserDao userDao;
public UserServiceImpl() {
}
public UserServiceImpl(UserDao userDao) {
this.userDao = userDao;
}
package com.cyz.demo;
import com.cyz.dao.UserDao;
import com.cyz.service.UserService;
import com.cyz.service.impl.UserServiceImpl;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class UserController {
public static void main(String[] args) {
ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
UserService userService = (UserService)app.getBean("userService");
userService.save();
}
}
Bean的依赖注入的数据类型
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以上注入的引用Bean,那么除了对象,普通类型,集合等都可以注入到容器
引用数据类型
普通数据类型
package com.cyz.dao.impl;
import com.cyz.dao.UserDao;
public class UserDaoImpl implements UserDao {
// 普通数据类型 set/get
private String username;
private int age;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public UserDaoImpl(){
System.out.println("UserDaoImpl无参构造。。。。");
}
<bean id="userDao" class="com.cyz.dao.impl.UserDaoImpl">
<property name="username" value="zhangsan"/>
<property name="age" value="18"/>
</bean>
package com.cyz.demo;
import com.cyz.service.UserService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class UserController {
public static void main(String[] args) {
ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
UserService userService = (UserService)app.getBean("userService");
userService.save();
}
}
集合数据类型
package com.cyz.dao.impl;
import com.cyz.dao.UserDao;
import com.cyz.domain.User;
import java.util.List;
import java.util.Map;
import java.util.Properties;
public class UserDaoImpl implements UserDao {
// 集合类型 get/set
private List<String> stringList;
private List<User> userList;
private Map<String, User> userMap;
private Properties properties;
public List<String> getStringList() {
return stringList;
}
public void setStringList(List<String> stringList) {
this.stringList = stringList;
}
public Map<String, User> getUserMap() {
return userMap;
}
public void setUserMap(Map<String, User> userMap) {
this.userMap = userMap;
}
public Properties getProperties() {
return properties;
}
public void setProperties(Properties properties) {
this.properties = properties;
}
public List<User> getUserList() {
return userList;
}
public void setUserList(List<User> userList) {
this.userList = userList;
}
public UserDaoImpl(){
System.out.println("UserDaoImpl无参构造。。。。");
}
package com.cyz.domain;
public class User {
private String name;
private String address;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}