Spring源代码学习系列〇源代码下载、导入与Hello World

比眉伴天荒 2023-07-21 06:25 18阅读 0赞

> 最近确实受到一些打击，开始思考人生、也开始思考自己到底缺的是什么。决定从spring源代码开始学习，是我在思考后，作出的决定。但是同时我也不会放弃netty，等稍微有点时间了，我会继续开始netty相关的学习。

说起来很是惭愧，因为项目中每天都在用这个框架，也觉得自己大致懂spring是干什么的，除了偶尔看看SpringMVC的代码外，很少看过spring以及SpringBoot相关的源码，以致于连SpringBoot的自动配置也只是知道个大概。最近几天看了看SpringBoot的自动配置源码，算是从代码上有了一个了解，但是同时感觉自己对每天都在用到的Spring还所知盛少。所以，在这样的基础上，还去看netty，有一种眼高手低、“起房子我只要顶楼”的感觉。所以还是从头开始吧，毕竟这个框架，在毕业前就一致被问来问去，到现在都还没说太清楚，确实很是惭愧。

## 源代码的克隆 ##

从 https://github.com/spring-projects/spring-framework 克隆源代码到本地，然后导入到idea中。

如果从github上面克隆比较慢，可以先在github上面fork一份源代码到自己的账号上；

![format_png][]

然后在gitee上，导入绑定的github账号下的项目，这个速度比较快；

![format_png 1][]

最后直接从gitee上面克隆。

git clone git@gitee.com:sasurai/spring-framework.git

这样操作的话，速度比较快。

## 源代码的导入 ##

看多了网上的各种教程，包括书上面的，都没有[官方导入说明][Link 1]来得直接。

> The following has been tested against IntelliJ IDEA 2016.2.2
> 
> ## Steps ##
> 
> *Within your locally cloned spring-framework working directory:*
> 
> 1.  Precompile `spring-oxm` with `./gradlew :spring-oxm:compileTestJava`
> 2.  Import into IntelliJ (File -> New -> Project from Existing Sources -> Navigate to directory -> Select build.gradle)
> 3.  When prompted exclude the `spring-aspects` module (or after the import via File-> Project Structure -> Modules)
> 4.  Code away
> 
> ## Known issues ##
> 
> 1.  `spring-core` and `spring-oxm` should be pre-compiled due to repackaged dependencies.  
>     See `*RepackJar` tasks in the build and https://youtrack.jetbrains.com/issue/IDEA-160605).
> 2.  `spring-aspects` does not compile due to references to aspect types unknown to  
>     IntelliJ IDEA. See https://youtrack.jetbrains.com/issue/IDEA-64446 for details. In the meantime, the  
>     ‘spring-aspects’ can be excluded from the project to avoid compilation errors.
> 3.  While JUnit tests pass from the command line with Gradle, some may fail when run from  
>     IntelliJ IDEA. Resolving this is a work in progress. If attempting to run all JUnit tests from within  
>     IntelliJ IDEA, you will likely need to set the following VM options to avoid out of memory errors:  
>     \-XX:MaxPermSize=2048m -Xmx2048m -XX:MaxHeapSize=2048m
> 4.  If you invoke “Rebuild Project” in the IDE, you’ll have to generate some test  
>     resources of the `spring-oxm` module again (`./gradlew :spring-oxm:compileTestJava`)
> 
> ## Tips ##
> 
> In any case, please do not check in your own generated .iml, .ipr, or .iws files.  
> You’ll notice these files are already intentionally in .gitignore. The same policy goes for eclipse metadata.
> 
> ## FAQ ##
> 
> Q. What about IntelliJ IDEA’s own [Gradle support][]?
> 
> A. Keep an eye on https://youtrack.jetbrains.com/issue/IDEA-53476

与maven类似，import之后会使用gradle构建整个项目，这个过程中会下载依赖，默认的依赖下载网址是国外的，很慢，所以构建需要很长时间，甚至出现构建失败。

1.  多试几次
2.  使用阿里镜像
    
     *  在用户目录下的.gradle中，新建init.gradle文件：`vim ~/.gradle/init.gradle`
     *  内容是从网上抄过来的，内容如下：
        
            allprojects {
                repositories {
                    def ALIYUN_REPOSITORY_URL = 'http://maven.aliyun.com/nexus/content/groups/public'
                    def ALIYUN_JCENTER_URL = 'http://maven.aliyun.com/nexus/content/repositories/jcenter'
                    all {
                        ArtifactRepository repo ->
                            if (repo instanceof MavenArtifactRepository) {
                                def url = repo.url.toString()
                                if (url.startsWith('https://repo1.maven.org/maven2')) {
                                    project.logger.lifecycle "Repository ${repo.url} replaced by $ALIYUN_REPOSITORY_URL."
                                    remove repo
                                }
                                if (url.startsWith('https://jcenter.bintray.com/')) {
                                    project.logger.lifecycle "Repository ${repo.url} replaced by $ALIYUN_JCENTER_URL."
                                    remove repo
                                }
                            }
                    }
                    maven {
                        url ALIYUN_REPOSITORY_URL
                        url ALIYUN_JCENTER_URL
                    }
                }
            }
3.  架个梯子（尝试了，但是想过不太理想，可能是梯子本身太慢）

构建完成后，各个模块能够突出显示出来，与用maven构建后的效果类似。

![format_png 2][]

## 来一个基于源码的Hello World ##

新建一个module，然后在新建module的build.gradle中，加入对spring-framework中子模块的依赖

dependencies {
        testCompile group: 'junit', name: 'junit', version: '4.12'
        compile project(":spring-core")
        compile project(":spring-beans")
        compile project(":spring-context")
    }

只要注意这个写法就行了，与maven中加入依赖的效果是类似的，然后新建一个bean类

package main.beans;
    
    public class TestBean {
        
    	private String name;
    
    	public String getName() {
        
    		return name;
    	}
    
    	public void setName(String name) {
        
    		this.name = name;
    	}
    
    	@Override
    	public String toString() {
        
    		return "TestBean{" +
    				"name='" + name + '\'' +
    				'}';
    	}
    }

xml配置文件。这段是从书上敲过来的，太坑了，连大小写都还要再改，搞得一脸懵逼。

<?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="testBean" class="main.beans.TestBean"/>
    </beans>

测试类

package main;
    
    import main.beans.TestBean;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    public class TestMainApplication {
        
    	public static void main(String[] args) {
        
    		ClassPathXmlApplicationContext beanFactory = new ClassPathXmlApplicationContext("beanFactoryTest.xml");
    		TestBean testBean = beanFactory.getBean(TestBean.class);
    		System.out.println(testBean);
    	}
    }

启动测试类，输出如下：

![format_png 3][]

愉快地开始spring吧！

[format_png]: /images/20230528/03d70a79de044a1483dac61e163daf27.png
[format_png 1]: /images/20230528/8c3d5bd065ca4bcab0c2f1db9c731705.png
[Link 1]: https://github.com/spring-projects/spring-framework/blob/master/import-into-idea.md
[Gradle support]: https://confluence.jetbrains.net/display/IDEADEV/Gradle+integration
[format_png 2]: /images/20230528/30e1f633828147a58633e292e5e9f76c.png
[format_png 3]: /images/20230528/9147ec0661a543ddb2fdb145ca777e18.png