[Java知识库]3. Spring-IOC操作Bean管理-基于xml配置文件实现1

一、基于xml方式创建对象

 <!--配置User对象创建-->
 <bean id="user" class="com.znb.spring5.User"></bean>

1. 在spring配置文件中使用bean标签，标签里面添加对应属性，就可以实现对象的创建。

2. bean标签中的常用属性

    id属性：唯一标识
    class属性：类的全路径
   

3. 创建对象的时候，默认也是去执行无参的构造方法。

二、基于xml方式注入属性

1. set方法注入属性

1. 创建实体类

package com.znb.spring5;

public class Book {

    private String bookName;
    private String bookAuthor;

    public String getBookAuthor() {
        return bookAuthor;
    }

    public void setBookAuthor(String bookAuthor) {
        this.bookAuthor = bookAuthor;
    }

    public String getBookName() {
        return bookName;
    }

    public void setBookName(String bookName) {
        this.bookName = bookName;
    }

    public void bookAndAuthor(){
        System.out.println(this.bookName + "的作者是" + this.bookAuthor);
    }
}

2. 编写配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

   <!-- &lt;!&ndash;配置User对象创建&ndash;&gt;
    <bean id="user" class="com.znb.spring5.User"></bean>-->

    <!--创建对象-->
    <bean id="book" class="com.znb.spring5.Book">
        <!--注入属性-->
        <property name="bookName" value="红楼梦"></property>
        <property name="bookAuthor" value="曹雪芹"></property>
    </bean>
</beans>

3. 测试

package com.znb.spring5;

import junit.framework.TestCase;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class BookTest extends TestCase {

    public void testBookAndAuthor() {
        ApplicationContext context = new ClassPathXmlApplicationContext("bean1.xml");
        Book book = context.getBean("book", Book.class);
        book.bookAndAuthor();
    }
}

4. 结果
   

2. 有参构造注入

1. 实体类

public class Orders {
    private String orderName;
    private String address;

    public Orders(String orderName, String address) {
        this.orderName = orderName;
        this.address = address;
    }

    public void Print(){
        System.out.println("订单名称： " + this.orderName + "; 订单地址： " + this.address);
    }

}

2. 编写配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
       
    <bean id="orders" class="com.znb.spring5.Orders">
        <constructor-arg name="orderName" value="手机"></constructor-arg>
        <constructor-arg name="address" value="China"></constructor-arg>
    </bean>

</beans>

3. 测试

public class OrdersTest extends TestCase {

    public void testPrint() {
        ApplicationContext context = new ClassPathXmlApplicationContext("bean1.xml");
        Orders orders = context.getBean("orders", Orders.class);
        orders.Print();

    }
}

4. 运行结果
   

3. 基于xml方式注入属性的特殊情况

①. null值

<!--注入空值null-->
    <bean id="orders" class="com.znb.spring5.Orders">
        <constructor-arg name="address">
            <null></null>
        </constructor-arg>
        <constructor-arg name="orderName" value="zz"></constructor-arg>
    </bean>

②. 特殊字符

<!--注入特殊字符
        1. 使用转义字符
        2. CDATA域
    -->
     <bean id="book" class="com.znb.spring5.Book">
        <!--注入属性-->
        <property name="bookName">
            <value>
                <![CDATA[<<特殊字符>>]]>
            </value>
        </property>
        <property name="bookAuthor" value="&lt;&gt;曹雪芹"></property>
    </bean>

4. 基于xml方式注入属性-外部bean

1. 创建service类和dao类

UserService类

public class UserService {

    //创建UserDao类型属性，生成set方法
    private UserDao userDao;

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

    public void add(){
        System.out.println("service add!");
        userDao.update();
    }
}

UserDao类

public interface UserDao {
    public void update();
}

UserDaoImpl类

public class UserDaoImpl implements UserDao {
    @Override
    public void update() {
        System.out.println("dao update!");
    }
}

2. 编写配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!--1. 创建service和dao对象-->
    <bean id="userService" class="com.znb.spring5.service.UserService">
        <!--2. 注入userDao对象
            name:为类中属性的名称
            ref:为创建的对象的id值
        -->
        <property name="userDao" ref="userDaoImpl"></property>
    </bean>
    <bean id="userDaoImpl" class="com.znb.spring5.dao.impl.UserDaoImpl"></bean>
</beans>

3. 测试类

public class UserServiceTest extends TestCase {

    public void testAdd() {
        ApplicationContext context = new ClassPathXmlApplicationContext("bean2.xml");
        UserService userService = context.getBean("userService", UserService.class);
        userService.add();
    }
}

4. 测试结果
   

5. 基于xml方式注入属性-内部bean和级联赋值

1. 实体类

//员工类
public class Emp {
    private String empName;
    private String gender;
    //员工属于的部门
    private Dept dept;

    public void setDept(Dept dept) {
        this.dept = dept;
    }

    public void setEmpName(String empName) {
        this.empName = empName;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public void show(){
        System.out.println("员工姓名： " + this.empName + "; 性别：" + this.gender + "; 部门： " + this.dept);
    }
}

//部门类
public class Dept {
    private String deptName;

    public void setDeptName(String deptName) {
        this.deptName = deptName;
    }

    @Override
    public String toString() {
        return "Dept{" +
                "deptName='" + deptName + '\'' +
                '}';
    }
}

2. 配置文件
   内部bean

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!--内部bean-->
    <bean id="emp" class="com.znb.spring5.bean.Emp">
        <!--设备两个普通属性-->
        <property name="empName" value="张三"></property>
        <property name="gender" value="男"></property>
        <!--设置对象类型属性-->
        <property name="dept">
            <bean id="dept" class="com.znb.spring5.bean.Dept">
                <property name="deptName" value="设计部"></property>
            </bean>
        </property>
    </bean>
</beans>

级联赋值

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!--级联赋值-->
    <bean id="emp" class="com.znb.spring5.bean.Emp">
        <property name="empName" value="李四"></property>
        <property name="gender" value="女"></property>
        <!--级联赋值-->
        <property name="dept" ref="dept1"></property>
    </bean>
    <bean id="dept1" class="com.znb.spring5.bean.Dept">
        <property name="deptName" value="安保部"></property>
    </bean>
</beans>

3. 测试内部bean

public class EmpTest extends TestCase {

    public void testShow() {
        ApplicationContext context = new ClassPathXmlApplicationContext("bean3.xml");
        Emp emp = context.getBean("emp", Emp.class);
        emp.show();
    }
}

4. 测试级联赋值

public class EmpTest1 extends TestCase {

    public void testShow() {
        ApplicationContext context = new ClassPathXmlApplicationContext("bean4.xml");
        Emp emp = context.getBean("emp", Emp.class);
        emp.show();
    }
}