深入理解ContextClassLoader加载器

Thread.currentThread().getContextClassLoader();
this.getClass().getClassLoader();

 /* The context ClassLoader for this thread */
    private ClassLoader contextClassLoader;

//获取文件绝对地址,并不是jar里面的文件路径
URL resource = BlmSignature.class.getClassLoader().getResource(keystoreFilePath);
String path = resource.getPath();
//当发布到线上只发布jar文件, 所以就会报异常,找不到
FileInputStream keystoreinputStream=new FileInputStream(path);

//正确的做法是,获取到jar包里面的文件,需要注意类加载是否能加载到的问题,
//1. Spring工具
keystorePath = "classpath:"+keystoreFilePath;
ClassPathResource classPathResource = new ClassPathResource(keystorePath);
InputStream keystoreinputStream = classPathResource.getInputStream();
//使用类加载器加载classpath里面的
//指定Thread.currentThread().getContextClassLoader();加载器
SmileClassPathResource smileClassPathResource = new SmileClassPathResource(keystoreFilePath);
InputStream  keystoreinputStream=smileClassPathResource.getInputStream();

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
/**
 * @Package: org.smileframework.tool.io
 * @Description: 加载配置文件
 * @author: liuxin
 * @date: 2017/12/19 上午9:23
 */
public class SmileClassPathResource {
    private final String path;
    private ClassLoader classLoader;
    public SmileClassPathResource(String name) {
        this(name, getDefaultClassLoader());
    }
    public SmileClassPathResource(String name, ClassLoader classLoader) {
        this.path = name;
        this.classLoader = classLoader;
    }
    public static ClassLoader getDefaultClassLoader() {
        ClassLoader cl = null;
        try {
            cl = Thread.currentThread().getContextClassLoader();
        } catch (Throwable var3) {
            ;
        }
        if(cl == null) {
            cl = ClassUtils.class.getClassLoader();
            if(cl == null) {
                try {
                    cl = ClassLoader.getSystemClassLoader();
                } catch (Throwable var2) {
                    ;
                }
            }
        }
        return cl;
    }
    public InputStream getInputStream() {
        InputStream is;
        if (this.classLoader != null) {
            is = this.classLoader.getResourceAsStream(this.path);
        } else {//当还是加载不到,调用上层加载器
            is = ClassLoader.getSystemResourceAsStream(this.path);
        }
        if (is == null) {
            throw new RuntimeException(path + " cannot be opened because it does not exist");
        } else {
            return is;
        }
    }
    public String getResourceStreamAsString() {
        InputStream is = getInputStream();
        BufferedReader reader = new BufferedReader(new InputStreamReader(is));
        StringBuilder sb = new StringBuilder();
        String line = null;
        try {
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                is.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return sb.toString();
    }
    public static void main(String[] args) {
        SmileClassPathResource classPathResource = new SmileClassPathResource("logback.xml");
        System.out.println(classPathResource.getResourceStreamAsString());
    }
}