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[Java知识库]spring课程学习2

SPring课程学习2

SpringIOC

spring注入

set注入

纯粹的set注入。都是简单的数据类型，在IOC容器中使用<property接定义即可

<bean id="student" class="com.lean_spring.entity.Student">
    <property name="gender" value="男"></property>
    <property name="intro" value="shuai"></property>
    <property name="salary" value="10.00"></property>
    <property name="ID" value="100"></property>
    <property name="name" value="name"></property>
</bean>

在测试中运行即可得到数据

在student中添加list类型

我们再创建一个Book类，在student中用list存储，

package com.lean_spring.entity;

public class Book {
    private String no;
    private String name;
    private String auther;

    @Override
    public String toString() {
        return "Book{" +
                "no='" + no + '\'' +
                ", name='" + name + '\'' +
                ", auther='" + auther + '\'' +
                '}';
    }

    public String getNo() {
        return no;
    }

    public void setNo(String no) {
        this.no = no;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAuther() {
        return auther;
    }

    public void setAuther(String auther) {
        this.auther = auther;
    }
}

student：

package com.lean_spring.entity;

import java.util.List;

public class Student {
    private Integer ID;
    private String name;
    private char gender;
    private Double salary;
    private String intro;
    private Computer computer;
    private List<Book> book;

    public Student() {
    }
    public Student(Integer ID, String name, char gender, Double salary, String intro, Computer computer) {
        this.ID = ID;
        this.name = name;
        this.gender = gender;
        this.salary = salary;
        this.intro = intro;
        this.computer = computer;
    }


    @Override
    public String toString() {
        return "Student{" +
                "ID=" + ID +
                ", name='" + name + '\'' +
                ", gender=" + gender +
                ", salary=" + salary +
                ", intro='" + intro + '\'' +
                ", computer=" + computer +
                ", book=" + book +
                '}';
    }

    public Integer getID() {
        return ID;
    }

    public void setID(Integer ID) {
        this.ID = ID;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public char getGender() {
        return gender;
    }

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

    public Double getSalary() {
        return salary;
    }

    public void setSalary(Double salary) {
        this.salary = salary;
    }

    public String getIntro() {
        return intro;
    }

    public void setIntro(String intro) {
        this.intro = intro;
    }
    public Computer getComputer() {
        return computer;
    }

    public void setComputer(Computer computer) {
        this.computer = computer;
    }

    public List<Book> getBook() {
        return book;
    }

    public void setBook(List<Book> book) {
        this.book = book;
    }
}

再IOC中声明它：

<bean id="student4" class="com.lean_spring.entity.Student">
    <property name="gender" value="男"></property>
    <property name="intro" value="shuai"></property>
    <property name="salary" value="10.00"></property>
    <property name="ID" value="100"></property>
    <property name="name" value="name"></property>
    <property name="computer" ref="computer"></property>
    <property name="book" >
        <list>

        </list>
    </property>
</bean>

在测试中我们同时测试student2与student4

@Test
    public void testStudentTest4(){
        Student student2=app.getBean("student2",Student.class);
        System.out.println(student2);
        Student student4=app.getBean("student4",Student.class);
        System.out.println(student4);
    }
}

运行后：

在这里插入图片描述

可以看到student2中的book是null而student4中则是空数据，student4多做一步new arrylist[]；

我们把book添加入数据（bean数据添加与ref的使用参考下文构造器注入），在IOC中添加：

<bean id="book" class="com.lean_spring.entity.Book">
    <property name="name" value="book1"></property>
    <property name="no" value="1"></property>
    <property name="auther" value="auther1"></property>
</bean>

<bean id="student4" class="com.lean_spring.entity.Student">
    <property name="gender" value="男"></property>
    <property name="intro" value="shuai"></property>
    <property name="salary" value="10.00"></property>
    <property name="ID" value="100"></property>
    <property name="name" value="name"></property>
    <property name="computer" ref="computer"></property>
    <property name="book" >
        <list>
            <ref bean="book"></ref>
            <bean id="book2" class="com.lean_spring.entity.Book">
                <property name="name" value="book2"></property>
                <property name="no" value="2"></property>
                <property name="auther" value="auther2"></property>
            </bean>
        </list>
    </property>
</bean>

在测试中再次运行testStudentTest4()

在这里插入图片描述

在student4中book已经有了数据而student2仍然是null。

在student中添加map类型

在student中添加map属性。增加get（），set（）方法，更新toString（）方法，其他照旧

package com.lean_spring.entity;

import java.util.List;
import java.util.Map;

public class Student {
    private Integer ID;
    private String name;
    private char gender;
    private Double salary;
    private String intro;
    private Computer computer;
    private List<Book> book;
    private Map<String ,Object> map;
    private Map<String ,Object> map2;

    @Override
    public String toString() {
        return "Student{" +
                "ID=" + ID +
                ", name='" + name + '\'' +
                ", gender=" + gender +
                ", salary=" + salary +
                ", intro='" + intro + '\'' +
                ", computer=" + computer +
                ", book=" + book +
                ", map=" + map +
                ", map2=" + map2 +
                '}';
    }

    public Map<String, Object> getMap2() {
        return map2;
    }

    public void setMap2(Map<String, Object> map2) {
        this.map2 = map2;
    }

    public Map<String, Object> getMap() {
        return map;
    }

    public void setMap(Map<String, Object> map) {
        this.map = map;
    }

    public Student() {
    }
    public Student(Integer ID, String name, char gender, Double salary, String intro, Computer computer) {
        this.ID = ID;
        this.name = name;
        this.gender = gender;
        this.salary = salary;
        this.intro = intro;
        this.computer = computer;
    }


    public Integer getID() {
        return ID;
    }

    public void setID(Integer ID) {
        this.ID = ID;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public char getGender() {
        return gender;
    }

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

    public Double getSalary() {
        return salary;
    }

    public void setSalary(Double salary) {
        this.salary = salary;
    }

    public String getIntro() {
        return intro;
    }

    public void setIntro(String intro) {
        this.intro = intro;
    }
    public Computer getComputer() {
        return computer;
    }

    public void setComputer(Computer computer) {
        this.computer = computer;
    }

    public List<Book> getBook() {
        return book;
    }

    public void setBook(List<Book> book) {
        this.book = book;
    }
}

在IOC中为map添加数据（在student4上进行添加）：

<bean id="student4" class="com.lean_spring.entity.Student">
        <property name="gender" value="男"></property>
        <property name="intro" value="shuai"></property>
        <property name="salary" value="10.00"></property>
        <property name="ID" value="100"></property>
        <property name="name" value="name"></property>
        <property name="computer" ref="computer"></property>
        <property name="book" >
            <list>
                <ref bean="book"></ref>
                <bean id="book2" class="com.lean_spring.entity.Book">
                    <property name="name" value="book2"></property>
                    <property name="no" value="2"></property>
                    <property name="auther" value="auther2"></property>
                </bean>
            </list>
        </property>
        <property name="map">
            <map>
                <entry key="性别" value="女"></entry>
                <entry key="电脑" value-ref="computer"></entry>
                <entry key="书籍" >
                    <bean id="book3" class="com.lean_spring.entity.Book">
                        <property name="name" value="book3"></property>
                        <property name="no" value="3"></property>
                        <property name="auther" value="auther3"></property>
                    </bean>
                </entry>
                <entry key="mp">
                    <map>
                        <entry key="子map" value="测试"></entry>
                    </map>
                </entry>
            </map>
        </property>
        <property name="map2" ref="map01"></property>
    </bean>
    <util:map id="map01">
        <entry key="key01" value="mp01"></entry>
        <entry key="key02" value="mp02"></entry>
        <entry key="key03" value="mp03"></entry>
        <entry key="key04" value="mp04"></entry>
    </util:map>

继续运行测试testStudentTest4()，map的数据就可以被引出来了：
在这里插入图片描述

对数据进行修改（以student示例）：

<bean id="student" class="com.lean_spring.entity.Student">
    <property name="gender" value="男"></property>
    <property name="intro" value="shuai"></property>
    <property name="salary" value="10.00"></property>
    <property name="ID" value="100"></property>
    <property name="name" value="name"></property>
    <property name="computer" ref="computer"></property>
    <property name="computer.brand" value="shako"></property>
</bean>

运行testStudentTest4()后：

在这里插入图片描述

可以看到student2与student4中computer的brand数据都被修改了。

构造器注入

首先在类中写入无常构造

package com.lean_spring.entity;

public class Student {
    private Integer ID;
    private String name;
    private char gender;
    private Double salary;
    private String intro;
    private Computer computer;

    public Student() {
    }

    public Student(Integer ID, String name, char gender, Double salary, String intro, Computer computer) {
        this.ID = ID;
        this.name = name;
        this.gender = gender;
        this.salary = salary;
        this.intro = intro;
        this.computer = computer;
    }

    public Computer getComputer() {
        return computer;
    }

    public void setComputer(Computer computer) {
        this.computer = computer;
    }

    @Override
    public String toString() {
        return "Student{" +
                "ID=" + ID +
                ", name='" + name + '\'' +
                ", gender=" + gender +
                ", salary=" + salary +
                ", intro='" + intro + '\'' +
                ", computer=" + computer +
                '}';
    }

    public Integer getID() {
        return ID;
    }

    public void setID(Integer ID) {
        this.ID = ID;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public char getGender() {
        return gender;
    }

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

    public Double getSalary() {
        return salary;
    }

    public void setSalary(Double salary) {
        this.salary = salary;
    }

    public String getIntro() {
        return intro;
    }

    public void setIntro(String intro) {
        this.intro = intro;
    }
}

在IOC中使用<constructor-arg定义

<bean id="computer" class="com.lean_spring.entity.Computer">
        <property name="id" value="dll"></property>
        <property name="brand" value="dsy"></property>
    </bean>

<bean id="student2" class="com.lean_spring.entity.Student">
    <constructor-arg name="ID" value="1000"></constructor-arg>
    <constructor-arg name="name" value="name"></constructor-arg>
    <constructor-arg name="gender" value='s'></constructor-arg>
    <constructor-arg name="salary" value="1000"></constructor-arg>
    <constructor-arg name="intro" value="评价"></constructor-arg>
    <constructor-arg name="computer" ref="computer"></constructor-arg>
</bean>

值得注意的是这里的computer对象使用ref标签可以指向注入它即可。

我们还可以利用bean来为数据注入对象：

<bean id="student3" class="com.lean_spring.entity.Student">
    <constructor-arg name="ID" value="1000"></constructor-arg>
    <constructor-arg name="name" value="name"></constructor-arg>
    <constructor-arg name="gender" value='s'></constructor-arg>
    <constructor-arg name="salary" value="1000"></constructor-arg>
    <constructor-arg name="intro" value="评价"></constructor-arg>
    <constructor-arg name="computer"><bean id="computer" class="com.lean_spring.entity.Computer">
        <property name="id" value="dll"></property>
        <property name="brand" value="dsy"></property>
    </bean></constructor-arg>
</bean>

在测试中运行：

@Test
public void testStudentTest3(){
    Student student3=app.getBean("student3",Student.class);
    System.out.println(student3);
}

依然可以得到computer的数据：
在这里插入图片描述

注解注入

大部分使用注解注入，相互依赖，需要开启自动扫描：

<!--    开启注解扫描-->
<context:annotation-config></context:annotation-config>
<context:component-scan base-package="com.lean_spring.entity"/>

bean的作用域

prototype表示多实例，每次获取对线的时候，IOC会创建一个对象

创建一个类C用于测试：

package com.lean_spring.entity;

public class C {
    public C() {

    }
}

在IOC中添加关于C的定义：

<bean id="c" class="com.lean_spring.entity.C" scope="prototype"></bean>

在测试中添加testC（）：

@Test
public void testC(){
    C c=app.getBean("c",C.class);
    System.out.println(c);
    C c2=app.getBean("c",C.class);
    System.out.println(c2);
}

运行后可以看到：

在这里插入图片描述

两个对象并不是同一个

singleton单实例，默认的，每次容器启动的时候，就会创建一个对象，每次获取的时候，都是获取这个对象

修改IOC中的scope属性就可开始测试：

<bean id="c" class="com.lean_spring.entity.C" scope="singleton"></bean>

再次运行测试：
在这里插入图片描述

两个c,c2是相同的一个对象。

request在web环境下，每次请求都会创建一个对象

session在web环境下，每一个会话周期会创建一个对象

bean的自动装配

autowire自动装配

default 默认值，关闭自动装配，使用手动装配

新建两个D，E类进行测试

package com.lean_spring.entity;

public class D {
    private E e;

    @Override
    public String toString() {
        return "D{" +
                "e=" + e +
                '}';
    }

    public E getE() {
        return e;
    }

    public void setE(E e) {
        this.e = e;
    }
}

package com.lean_spring.entity;

public class E {
    private String name;

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

在IOC容器中来声明：

<bean id="d" class="com.lean_spring.entity.D" autowire="default">
    </bean>
    <bean id="e" class="com.lean_spring.entity.E">
        <property name="name" value="eeee"></property>
    </bean>

在进行测试

 @Test
    public void testDE(){
        D d=app.getBean("d",D.class);
        System.out.println(d);
    }
}

在这里插入图片描述

可以发现其运行出的是空值

byname通过bean的名称进行自动装配，要求名称与bean的名称一致

更改IOC中d的autowire标签

<bean id="d" class="com.lean_spring.entity.D" autowire="byName">
</bean>
<bean id="e" class="com.lean_spring.entity.E">
    <property name="name" value="eeee"></property>
</bean>

再次运行textSE（）：

在这里插入图片描述

e中的数据已经被装配好了

bytype通过类型来进行自动装配，要求同一个类型在IOC容器中只能有一个

同样修改IOC后运行依然可以装配

如果IOC中E类型有2个以上那么bean会报错：

在这里插入图片描述

通过构造器进行注入

先在D类中加入构造器

package com.lean_spring.entity;

public class D {
    private E e;

    public D() {
    }

    public D(E e) {
        this.e = e;
    }

    @Override
    public String toString() {
        return "D{" +
                "e=" + e +
                '}';
    }

    public E getE() {
        return e;
    }

    public void setE(E e) {
        this.e = e;
    }
}

constructor先通过名称来查找，然后对照类型进行查找，当有两个形同类型时不会报错

<bean id="d" class="com.lean_spring.entity.D" autowire="constructor">
    </bean>
    <bean id="e" class="com.lean_spring.entity.E">
        <property name="name" value="eeee"></property>
    </bean><bean id="e2" class="com.lean_spring.entity.E">
    <property name="name" value="eeee2"></property>
</bean>