关于spring，以及spring基于XML文件和注解的简单实现

一时失言乱红尘 2022-05-14 05:43 93阅读 0赞

什么是spring？

Spring是一个开源的轻量级Java SE（Java 标准版本）/Java EE（Java 企业版本）开发应用框架，其目的是用于简化企业级应用程序开发。是一个开源框架，是一个bean类工厂，核心是控制反转（IOC）、依赖注入(DI)和面向切面（AOP）。
在日常开发过程中，能提高我们的开发速度以及程序的性能：

  1. 高内聚低耦合：
    Spring就是一个大工厂（容器），可以将所有对象创建和依赖关系维护，交给Spring管理 ，客户端需要某个对象从而不需要主动的调用，而是对象被动的直接注入(DI)过来;
  2. AOP编程的支持
    Spring提供面向切面编程，可以方便的实现对程序进行权限拦截、运行监控等功能
  3. 方便集成各种优秀框架
    Spring不排斥各种优秀的开源框架，其内部提供了对各种优秀框架（如：Struts、Hibernate、MyBatis、Quartz等）的直接支持
  4. 降低JavaEE API的使用难度
    Spring 对JavaEE开发中非常难用的一些API（JDBC、JavaMail、远程调用等），都提供了封装，使这些API应用难度大大降低。

案例：控制反转、依赖注入bean类基于XML文件

1.pom文件配置
根据创建的Maven项目，项目所需要依赖何种jar包都可以直接去maven仓库找到依赖源。（maven仓库：https://mvnrepository.com/）

  1. <?xml version="1.0" encoding="UTF-8"?>
  3. <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  4.     <modelVersion>4.0.0</modelVersion>
  6.     <groupId>com.yc.hui</groupId>
  7.     <artifactId>maven_spring</artifactId>
  8.     <version>0.0.1-SNAPSHOT</version>
  9.     <packaging>war</packaging>
  11.     <name>maven_spring Maven Webapp</name>
  12.     <!-- FIXME change it to the project's website -->
  13.     <url>http://www.example.com</url>
  15.     <properties>
  16.         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  17.         <maven.compiler.source>1.7</maven.compiler.source>
  18.         <maven.compiler.target>1.7</maven.compiler.target>
  19.     </properties>
  21.     <dependencies>
  22.         <dependency>
  23.             <groupId>junit</groupId>
  24.             <artifactId>junit</artifactId>
  25.             <version>4.11</version>
  26.             <scope>test</scope>
  27.         </dependency>
  29.             <!--下面这俩个为spring的依赖jar包，必须要有这俩个，我们的spring容器才能加载项目才能启动成功-->
  30.         <dependency>
  31.             <groupId>org.springframework</groupId>
  32.             <artifactId>spring-context</artifactId>
  33.             <version>5.0.6.RELEASE</version>
  34.         </dependency>
  35.         <dependency>
  36.             <groupId>org.springframework</groupId>
  37.             <artifactId>spring-core</artifactId>
  38.             <version>5.0.6.RELEASE</version>
  39.         </dependency>
  42.     </dependencies>
  44.     <build>
  45.         <finalName>maven_spring</finalName>
  46.         <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
  47.             <plugins>
  48.                 <plugin>
  49.                     <artifactId>maven-clean-plugin</artifactId>
  50.                     <version>3.0.0</version>
  51.                 </plugin>
  52.                 <!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
  53.                 <plugin>
  54.                     <artifactId>maven-resources-plugin</artifactId>
  55.                     <version>3.0.2</version>
  56.                 </plugin>
  57.                 <plugin>
  58.                     <artifactId>maven-compiler-plugin</artifactId>
  59.                     <version>3.7.0</version>
  60.                 </plugin>
  61.                 <plugin>
  62.                     <artifactId>maven-surefire-plugin</artifactId>
  63.                     <version>2.20.1</version>
  64.                 </plugin>
  65.                 <plugin>
  66.                     <artifactId>maven-war-plugin</artifactId>
  67.                     <version>3.2.0</version>
  68.                 </plugin>
  69.                 <plugin>
  70.                     <artifactId>maven-install-plugin</artifactId>
  71.                     <version>2.5.2</version>
  72.                 </plugin>
  73.                 <plugin>
  74.                     <artifactId>maven-deploy-plugin</artifactId>
  75.                     <version>2.8.2</version>
  76.                 </plugin>
  77.             </plugins>
  78.         </pluginManagement>
  79.     </build>
  80. </project>

其中….依赖jar包
2.在src/main/resource路径下创建一个xxxx.xml作为spring的容器配置文件
我这里命名为application.xml

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 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">
  4.   <bean id="student" class="com.yc.bean.Student">
  5.         <property name="sid" value="1"></property>
  6.         <property name="sname" value="hui"></property>
  7.     </bean>
  9. </beans>

3.bean类
封装一个和application.xml配置文件中的类

  1. package com.yc.bean;
  3. import java.io.Serializable;
  5. public class Student implements Serializable{ 
  6.     private int sid;
  7.     private String sname;
  9.     @Override
  10.     public String toString() {
  11.         return "Student [sid=" + sid + ", sname=" + sname + "]";
  12.     }
  13.     /** * */
  14.     private static final long serialVersionUID = 1L;
  15.     public Student() {
  16.         super();
  17.         // TODO Auto-generated constructor stub
  18.     }
  19.     public int getSid() {
  20.         return sid;
  21.     }
  22.     public void setSid(int sid) {
  23.         this.sid = sid;
  24.     }
  25.     public String getSname() {
  26.         return sname;
  27.     }
  28.     public void setSname(String sname) {
  29.         this.sname = sname;
  30.     }
  32.     public Student(int sid, String sname) {
  33.         super();
  34.         this.sid = sid;
  35.         this.sname = sname;
  36.     }
  40. }

4.测试代码

  1. package com.yc.test;
  3. import org.junit.Test;
  4. import org.springframework.context.ApplicationContext;
  6. import org.springframework.context.support.ClassPathXmlApplicationContext;
  9. import com.yc.bean.Student;
  12. public class TTest {
  13.     @Test
  14.     public void test1(){
  15.         ApplicationContext context = new ClassPathXmlApplicationContext(new String[] {
  16.    "application.xml"});
  17.         Student s=(Student) context.getBean("student");
  19.         System.out.println(s);
  20.     }

5.测试结果：

这里写图片描述

案例：控制反转、依赖注入bean类基于注解

1.pom文件配置

  1. <?xml version="1.0" encoding="UTF-8"?>
  3. <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  4.     <modelVersion>4.0.0</modelVersion>
  6.     <groupId>com.yc.hui</groupId>
  7.     <artifactId>maven_spring</artifactId>
  8.     <version>0.0.1-SNAPSHOT</version>
  9.     <packaging>war</packaging>
  11.     <name>maven_spring Maven Webapp</name>
  12.     <!-- FIXME change it to the project's website -->
  13.     <url>http://www.example.com</url>
  15.     <properties>
  16.         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  17.         <maven.compiler.source>1.7</maven.compiler.source>
  18.         <maven.compiler.target>1.7</maven.compiler.target>
  19.     </properties>
  21.     <dependencies>
  22.         <dependency>
  23.             <groupId>junit</groupId>
  24.             <artifactId>junit</artifactId>
  25.             <version>4.11</version>
  26.             <scope>test</scope>
  27.         </dependency>
  29.             <!--下面这俩个为spring的依赖jar包，必须要有这俩个，我们的spring容器才能加载项目才能启动成功-->
  30.         <dependency>
  31.             <groupId>org.springframework</groupId>
  32.             <artifactId>spring-context</artifactId>
  33.             <version>5.0.6.RELEASE</version>
  34.         </dependency>
  35.         <dependency>
  36.             <groupId>org.springframework</groupId>
  37.             <artifactId>spring-core</artifactId>
  38.             <version>5.0.6.RELEASE</version>
  39.         </dependency>
  42.     </dependencies>
  44.     <build>
  45.         <finalName>maven_spring</finalName>
  46.         <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
  47.             <plugins>
  48.                 <plugin>
  49.                     <artifactId>maven-clean-plugin</artifactId>
  50.                     <version>3.0.0</version>
  51.                 </plugin>
  52.                 <!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
  53.                 <plugin>
  54.                     <artifactId>maven-resources-plugin</artifactId>
  55.                     <version>3.0.2</version>
  56.                 </plugin>
  57.                 <plugin>
  58.                     <artifactId>maven-compiler-plugin</artifactId>
  59.                     <version>3.7.0</version>
  60.                 </plugin>
  61.                 <plugin>
  62.                     <artifactId>maven-surefire-plugin</artifactId>
  63.                     <version>2.20.1</version>
  64.                 </plugin>
  65.                 <plugin>
  66.                     <artifactId>maven-war-plugin</artifactId>
  67.                     <version>3.2.0</version>
  68.                 </plugin>
  69.                 <plugin>
  70.                     <artifactId>maven-install-plugin</artifactId>
  71.                     <version>2.5.2</version>
  72.                 </plugin>
  73.                 <plugin>
  74.                     <artifactId>maven-deploy-plugin</artifactId>
  75.                     <version>2.8.2</version>
  76.                 </plugin>
  77.             </plugins>
  78.         </pluginManagement>
  79.     </build>
  80. </project>

其中….依赖jar包
2.创建一个类作为spring的容器

  1. package com.yc.bean;
  3. import org.springframework.context.annotation.Bean;
  4. import org.springframework.context.annotation.ComponentScan;
  5. import org.springframework.context.annotation.Configuration;
  7. @Configuration          //表示这是个容器
  8. public class App {
  9.     @Bean
  10.     public Student student(){
  11.         Student s= new Student();
  12.         s.setSid(1);
  13.         s.setSname("a");
  14.         return s;
  15.     }
  16. }

3.bean类

  1. package com.yc.bean;
  3. import java.io.Serializable;
  5. import org.springframework.stereotype.Component;
  6. import org.springframework.stereotype.Repository;
  8. //@Repository //Dao层
  9. //@Component //通用注解
  10. public class Student implements Serializable{ 
  11.     private int sid;
  12.     private String sname;
  13.     @Override
  14.     public String toString() {
  15.         return "Student [sid=" + sid + ", sname=" + sname + "]";
  16.     }
  17.     /** * */
  18.     private static final long serialVersionUID = 1L;
  19.     public Student() {
  20.         super();
  21.         // TODO Auto-generated constructor stub
  22.     }
  23.     public int getSid() {
  24.         return sid;
  25.     }
  26.     public void setSid(int sid) {
  27.         this.sid = sid;
  28.     }
  29.     public String getSname() {
  30.         return sname;
  31.     }
  32.     public void setSname(String sname) {
  33.         this.sname = sname;
  34.     }
  36.     public Student(int sid, String sname) {
  37.         super();
  38.         this.sid = sid;
  39.         this.sname = sname;
  40.     }
  44. }

4.测试代码

  1. package com.yc.test;
  3. import org.junit.Test;
  4. import org.springframework.context.ApplicationContext;
  5. import org.springframework.context.annotation.AnnotationConfigApplicationContext;
  7. import com.yc.bean.App;
  8. import com.yc.bean.Student;
  11. public class TTest {
  12.     @Test
  13.     public void test5(){
  14.         ApplicationContext context=new AnnotationConfigApplicationContext(App.class);
  15.         Student s=(Student)context.getBean("student");
  16.         System.out.println(s);
  17.     }

5.测试结果
这里写图片描述

下一篇咱们介绍springmvc的相关知识，编写不易，谢谢各位支持。

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