初识Spring(四)

spring注入和MVC

action->service->dao

以前我们需要在action中new service的对象才能调用service中的方法，对应service调用dao层中的方法也是如此，现在spring要把这个解放出来。

step1 新建entity对象

User.java

package cn.itcast.c_property;public class User {    private int id;    private String name;    //////////////////  --> 通过容器注入属性值    public void setId(int id) {        this.id = id;    }    // //--> 通过容器注入属性值    public void setName(String name) {        this.name = name;    }    ////////////////    public int getId() {        return id;    }    public String getName() {        return name;    }    @Override    public String toString() {        return "User [id=" + id + ", name=" + name + "]";    }    public User() {        super();        System.out.println("------User对象创建【无参数构造器】------");    }    public User(int id, String name) {        System.out.println("-----User对象创建【带参数构造器】--------");        this.id = id;        this.name = name;    }    public void init_user() {        System.out.println("创建对象之后，初始化");    }    public void destroy_user() {        System.out.println("IOC容器销毁，user对象回收!");    }}

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UserDao.java

package cn.itcast.c_property;public class UserDao {    public void save() {        System.out.println("DB:保存用户");    }}

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UserService.java

package cn.itcast.c_property;public class UserService {    private UserDao userDao; // = new UserDao();    // IOC：对象的创建交给spring的外部容器完成    public void setUserDao(UserDao userDao) {        this.userDao = userDao;    }    public void save() {        userDao.save();    }}

UserAction.java

package cn.itcast.c_property;public class UserAction {    // Service: springIOC容器注入    private UserService userService;    public void setUserService(UserService userService) {        this.userService = userService;    }    public String execute() {        userService.save();        return null;    }}

step2 配置bean.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:p="http://www.springframework.org/schema/p"    xmlns:context="http://www.springframework.org/schema/context"    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">    <!-- ###############对象属性赋值############### -->    <!--  1) 通过构造函数 -->    <bean id="user1" class="cn.itcast.c_property.User" scope="prototype">        <constructor-arg value="100"></constructor-arg>        <constructor-arg value="Tom"></constructor-arg>    </bean>    <!-- 2) 通过set方法给属性注入值 -->    <bean id="user" class="cn.itcast.c_property.User" scope="prototype">        <property name="id" value="101"></property>        <property name="name" value="Jack"></property>    </bean>    <!--         案例：            action/service/dao     -->    <!-- dao instance -->    <bean id="userDao" class="cn.itcast.c_property.UserDao"></bean>    <!-- service instance -->    <bean id="userService" class="cn.itcast.c_property.UserService">        <property name="userDao" ref="userDao"></property>    </bean>    <!-- action instance -->    <bean id="userAction1" class="cn.itcast.c_property.UserAction">        <property name="userService" ref="userService"></property>    </bean></beans>      

Test.java
首先我们测试一下使用set方法给对象赋值

    @Test    public void testSet() {        // 从容器中获取        User user = (User) ac.getBean("user");        System.out.println(user);    }

运行结果：

——User对象创建【无参数构造器】——
User [id=101, name=Jack]

第二：

package cn.itcast.c_property;import org.junit.Test;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class App {    // 创建容器对象    private ApplicationContext ac = new ClassPathXmlApplicationContext("cn/itcast/c_property/bean.xml");    @Test    public void testExecuteAction() {        // 从容器中获取Action        UserAction userAction = (UserAction) ac.getBean("userAction1");        userAction.execute();    }}

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运行结果：

DB:保存用户

还有一个p空间需要spring 3.x以上才支持