Spring DI依赖注入实战教程_Java

1 概述

依赖
- a对象中有着b对象的引用，需要使用b对象完成一些操作
- a对象依赖b
注入
- 给a对象依赖的b对象赋值称为注入

2 注入方式

1、set注入

2、构造注入

3、自动注入

4、p命名空间注入

3 可以注入的数据类型

基本类型

自定义对象

容器类型

数组

集合

map

properties

4 set注入

创建对象的时候，spring工厂会调用set方法给对象中的属性赋值
如果一个对象中的属性没有添加set方法，使用property赋值的时候偶会报错

error:(11, 13) java: 找不到符号
  符号:   方法 setid(int)
  位置: 类型为com.sw.entity.user的变量 user

import lombok.data;
@data
public class user {
    private integer id;
    private string username;
    private string password;
    private string addr;
    private string info;
}

<!--  定义user  -->
<bean id="user" class="com.sw.entity.user">
    <property name="id" value="100111"></property>
    <property name="username" value="关羽"></property>
    <property name="info" value="卖杂粮的关羽"></property>
</bean>

5 构造器注入

通过对象的构造器注入属性

<constructor-arg name="id" value="100110"></constructor-arg>

package com.sw.entity;
public class hero {
    private integer id;
    private string username;
    private string password;
    private string addr;
    private string info;
    public hero() {
    }
    public hero(string username, string password) {
        this.username = username;
        this.password = password;
    }
    public hero(integer id, string username) {
        this.id = id;
        this.username = username;
    }
    public hero(integer id, string username, string password, string addr, string info) {
        this.id = id;
        this.username = username;
        this.password = password;
        this.addr = addr;
        this.info = info;
    }
    @override
    public string tostring() {
        return "hero{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", addr='" + addr + '\'' +
                ", info='" + info + '\'' +
                '}';
    }
}

    <!--  定义hero  -->
    <bean id="hero" class="com.sw.entity.hero">
        <constructor-arg name="id" value="100110"></constructor-arg>
        <constructor-arg name="username" value="刘备"></constructor-arg>
    </bean>
    <bean id="hero02" class="com.sw.entity.hero">
        <constructor-arg name="username" value="赵云"></constructor-arg>
        <constructor-arg name="password" value="zhao"></constructor-arg>
    </bean>

6 自动注入

在bean标签中声明autowire的方式

spring框架会在容器中查找符合参数的数据进行注入

bytype
byname

package com.sw.service.impl;
import com.sw.dao.herodao;
import com.sw.entity.hero;
import com.sw.service.heroservice;
public class heroserviceimpl implements heroservice {
    private herodao herodao;
    public void setherodao(herodao herodao) {
        this.herodao = herodao;
    }
    @override
    public hero queryherobyid(integer id) {
        return herodao.selectherobyid(id);
    }
}

    <!--  heroservice  -->
    <bean id="heroservice01" class="com.sw.service.impl.heroserviceimpl" autowire="bytype"></bean>
    <!--  heroservice  -->
    <bean id="heroservice02" class="com.sw.service.impl.heroserviceimpl" autowire="byname"></bean>

    @test
    public void gethero01(){
        classpathxmlapplicationcontext ioc = new classpathxmlapplicationcontext("applicationcontext.xml");
        heroservice heroservice = ioc.getbean("heroservice01",heroservice.class);
        hero hero = heroservice.queryherobyid(10010);
        system.out.println(hero);
    }
    @test
    public void gethero02(){
        classpathxmlapplicationcontext ioc = new classpathxmlapplicationcontext("applicationcontext.xml");
        heroservice heroservice = ioc.getbean("heroservice02",heroservice.class);
        hero hero = heroservice.queryherobyid(1001111);
        system.out.println(hero);
    }

自动注入还是通过set注入的方式注入

7 p命名空间注入

使用p作为属性的前缀，调用属性执行复制的操作
实质上还是使用set方法赋值

xmlns:p=“http://www.springframework.org/schema/p”

    <!--  stu  -->
    <bean id="stu" class="com.sw.entity.stu" p:id="100111" p:username="张三"></bean>

    @test
    public void getstu(){
        classpathxmlapplicationcontext ioc = 
        	new classpathxmlapplicationcontext("applicationcontext.xml");
        stu stu = ioc.getbean(stu.class);
        system.out.println(stu);
    }

8 数据源注入

使用spring工厂注入druid数据源
依赖

        <dependency>
            <groupid>com.alibaba</groupid>
            <artifactid>druid</artifactid>
            <version>1.1.10</version>
        </dependency>
        <dependency>
            <groupid>mysql</groupid>
            <artifactid>mysql-connector-java</artifactid>
            <version>5.1.47</version>
        </dependency>

在dao中声明数据源的引用

package com.sw.dao.impl;
import com.alibaba.druid.pool.druiddatasource;
import com.sw.dao.herodao;
import com.sw.entity.hero;
import java.sql.sqlexception;
public class herodaoimpl implements herodao {
    private druiddatasource datasource;
    public druiddatasource getdatasource() {
        return datasource;
    }
    public void setdatasource(druiddatasource datasource) {
        this.datasource = datasource;
    }
    @override
    public hero selectherobyid(integer id) {
        try {
            system.out.println(datasource.getconnection());
        } catch (sqlexception e) {
            e.printstacktrace();
        }
        hero hero = new hero();
        hero.setid(id);
        return hero;
    }
}

配置

      <!--  引入外部配置文件  -->
    <context:property-placeholder location="classpath:jdbc.properties"></context:property-placeholder>
  <!-- 配置数据源   -->
    <bean id="datasource" class="com.alibaba.druid.pool.druiddatasource">
        <property name="driverclassname" value="${jdbc.driver}"></property>
        <property name="url" value="${jdbc.url}"></property>
        <property name="username" value="${jdbc.username}"></property>
        <property name="password" value="${jdbc.password}"></property>
    </bean>
    <!--  herodao  -->
    <bean id="herodao" class="com.sw.dao.impl.herodaoimpl">
        <property name="datasource" ref="datasource"></property>
    </bean>

测试

package com.sw;
import com.sw.dao.herodao;
import com.sw.entity.hero;
import org.junit.test;
import org.springframework.context.support.classpathxmlapplicationcontext;
import java.sql.sqlexception;
public class testherodao {
    @test
    public void getherodao() {
        classpathxmlapplicationcontext ioc = new classpathxmlapplicationcontext("applicationcontext.xml");
        herodao herodao = ioc.getbean(herodao.class);
        hero hero = herodao.selectherobyid(222);
    }
}

4.9 容器类型数据注入

package com.sw.entity;
import lombok.data;
import java.util.list;
import java.util.map;
@data
public class person {
    private integer id;
    private string username;
    private string gender;
    private string info;
    private string[] hobby;
    private list<string> friend;
    private map<string,string> phones;
}

<?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
       https://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       https://www.springframework.org/schema/context/spring-context.xsd">
    <!--  person基本属性注入  -->
    <bean id="person01" class="com.sw.entity.person">
        <property name="id" value="100100"></property>
        <property name="username" value="宋江"></property>
        <property name="gender" value="male"></property>
        <property name="info" value="梁山头头"></property>
    </bean>
    <!--  注入数组  -->
    <bean id="person02" class="com.sw.entity.person">
        <property name="hobby">
            <array>
                <value>篮球</value>
                <value>足球</value>
                <value>乒乓球</value>
            </array>
        </property>
    </bean>
    <bean id="person03" class="com.sw.entity.person">
        <property name="friend">
            <list>
                <value>晁盖</value>
                <value>扈三娘</value>
                <value>王婆</value>
                <value>武松</value>
            </list>
        </property>
    </bean>
    <!--  map参数  -->
    <bean id="person04" class="com.sw.entity.person">
        <property name="phones">
            <map>
                <entry key="鲁智深" value="10010"></entry>
                <entry key="林冲" value="10086"></entry>
                <entry key="李逵" value="10000"></entry>
                <entry key="李鬼" value="100000"></entry>
            </map>
        </property>
    </bean>
</beans>

package com.sw;
import com.sw.entity.person;
import org.junit.test;
import org.springframework.context.support.classpathxmlapplicationcontext;
public class testperson {
    @test
    public void getperson01(){
        classpathxmlapplicationcontext ioc = new classpathxmlapplicationcontext("applicationcontext.xml");
        person person01 = ioc.getbean("person01", person.class);
        system.out.println(person01);
    }
    @test
    public void getperson02(){
        classpathxmlapplicationcontext ioc = new classpathxmlapplicationcontext("applicationcontext.xml");
        person person02 = ioc.getbean("person02", person.class);
        system.out.println(person02);
    }
    @test
    public void getperson03(){
        classpathxmlapplicationcontext ioc = new classpathxmlapplicationcontext("applicationcontext.xml");
        person person03 = ioc.getbean("person03", person.class);
        system.out.println(person03);
    }
    @test
    public void getperson04(){
        classpathxmlapplicationcontext ioc = new classpathxmlapplicationcontext("applicationcontext.xml");
        person person04 = ioc.getbean("person04", person.class);
        system.out.println(person04);
    }
}

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