ClassPathXmlApplicationContext源码分析

Posted 2021-03-20 凌林的芳香

ClassPathXmlApplicationContext源码解读

入口函数

通过ClassPathXmlApplicationContext类构造方法启动父类AbstractApplicationContext的函数refresh方法

ClassPathXmlApplicationContext源码：

package org.springframework.context.support;
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import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
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public class ClassPathXmlApplicationContext extends AbstractXmlApplicationContext {
    @Nullable
    private Resource[] configResources;
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    public ClassPathXmlApplicationContext() {
    }
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    public ClassPathXmlApplicationContext(ApplicationContext parent) {
        super(parent);
    }
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    public ClassPathXmlApplicationContext(String configLocation) throws BeansException {
        this(new String[]{configLocation}, true, (ApplicationContext)null);
    }
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    public ClassPathXmlApplicationContext(String... configLocations) throws BeansException {
        this(configLocations, true, (ApplicationContext)null);
    }
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    public ClassPathXmlApplicationContext(String[] configLocations, @Nullable ApplicationContext parent) throws BeansException {
        this(configLocations, true, parent);
    }
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    public ClassPathXmlApplicationContext(String[] configLocations, boolean refresh) throws BeansException {
        this(configLocations, refresh, (ApplicationContext)null);
    }
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    public ClassPathXmlApplicationContext(String[] configLocations, boolean refresh, @Nullable ApplicationContext parent) throws BeansException {
        super(parent);
        this.setConfigLocations(configLocations);
        if (refresh) {
            this.refresh();
        }
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    }
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    public ClassPathXmlApplicationContext(String path, Class<?> clazz) throws BeansException {
        this(new String[]{path}, clazz);
    }
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    public ClassPathXmlApplicationContext(String[] paths, Class<?> clazz) throws BeansException {
        this(paths, clazz, (ApplicationContext)null);
    }
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    public ClassPathXmlApplicationContext(String[] paths, Class<?> clazz, @Nullable ApplicationContext parent) throws BeansException {
        super(parent);
        Assert.notNull(paths, "Path array must not be null");
        Assert.notNull(clazz, "Class argument must not be null");
        this.configResources = new Resource[paths.length];
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        for(int i = 0; i < paths.length; ++i) {
            this.configResources[i] = new ClassPathResource(paths[i], clazz);
        }
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        this.refresh();
    }
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    @Nullable
    protected Resource[] getConfigResources() {
        return this.configResources;
    }
}
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ClassPathXmlApplicationContext(String configLocation) 一般使用这个方法，传入一个string类型的xml文件名，通过xml配置文件指定特定的组件，实例化到bean工厂里，即DefaultSingletonBeanRegistry 下的Map集合里

ClassPathXmlApplicationContext(String... configLocations)：可传入多个xml，装配到spring，bean工厂

public ClassPathXmlApplicationContext(String[] configLocations, boolean refresh) :传入String数组

@Test
    public void TestXmlBean(){
        ClassPathXmlApplicationContext context =new ClassPathXmlApplicationContext("classpath:xmlRegBean.xml");
        Animal cat =context.getBean("cat", Cat.class);
        cat.getName();
    }
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    @Test
    public void TestMultiXml(){
            ClassPathXmlApplicationContext context =new ClassPathXmlApplicationContext("classpath:xmlRegBean.xml","classpath:xmlRegBean2.xml");
            Animal cat =context.getBean("cat", Cat.class);
            cat.getName();
            System.out.println(cat);
            Animal cat2 =context.getBean("cat2", Cat.class);
            cat2.getName();
            System.out.println(cat2);
    }
    
 @Test
    public void TestArrayXml(){
        String[] arrXml = {"classpath:xmlRegBean.xml","classpath:xmlRegBean2.xml"};
        ClassPathXmlApplicationContext context =new ClassPathXmlApplicationContext(arrXml,true);
        Animal cat =context.getBean("cat", Cat.class);
        cat.getName();
        System.out.println(cat);
        Animal cat2 =context.getBean("cat2", Cat.class);
        cat2.getName();
        System.out.println(cat2);
    }