package org.springframework.boot.diagnostics;
/**
 * 該接口用戶分析異常堆棧信息，將其轉(zhuǎn)換為用戶可讀的對(duì)象信息，通常情況下，對(duì)象包含錯(cuò)誤描述和建議.
 * @since 1.4.0
 */
@FunctionalInterface
public interface FailureAnalyzer {
	/**
	 * 返回異常錯(cuò)誤的分析對(duì)象，或null
	 * @param failure the failure
	 * @return the analysis or {@code null}
	 */
	FailureAnalysis analyze(Throwable failure);
}

package org.springframework.boot.diagnostics;
/**
 * The result of analyzing a failure.
 *
 * @author Andy Wilkinson
 * @since 1.4.0
 */
public class FailureAnalysis {
  // 問題描述
	private final String description;
  // 動(dòng)作(解決問題的方法)
	private final String action;
  // 問題原因
	private final Throwable cause;
	public FailureAnalysis(String description, String action, Throwable cause) {
		this.description = description;
		this.action = action;
		this.cause = cause;
	}
  // get 方法...
}

package org.springframework.boot.diagnostics.analyzer;
import org.springframework.boot.diagnostics.AbstractFailureAnalyzer;
import org.springframework.boot.diagnostics.FailureAnalysis;
import org.springframework.boot.web.server.PortInUseException;
class PortInUseFailureAnalyzer extends AbstractFailureAnalyzer<PortInUseException> {
	@Override
	protected FailureAnalysis analyze(Throwable rootFailure, PortInUseException cause) {
		return new FailureAnalysis("Web server failed to start. Port " + cause.getPort() + " was already in use.",
				"Identify and stop the process that's listening on port " + cause.getPort() + " or configure this "
						+ "application to listen on another port.",
				cause);
	}
}

public abstract class AbstractFailureAnalyzer<T extends Throwable> implements FailureAnalyzer {
	@Override
	public FailureAnalysis analyze(Throwable failure) {
		T cause = findCause(failure, getCauseType());
		return (cause != null) ? analyze(failure, cause) : null;
	}
	/**
	 * 重新定義鉤子方法，將參數(shù)與泛型對(duì)象關(guān)聯(lián)，具象化了每一個(gè)子類需要實(shí)現(xiàn)的功能
	 */
	protected abstract FailureAnalysis analyze(Throwable rootFailure, T cause);
	@SuppressWarnings("unchecked")
	protected Class<? extends T> getCauseType() {
		return (Class<? extends T>) ResolvableType.forClass(AbstractFailureAnalyzer.class, getClass()).resolveGeneric();
	}
	@SuppressWarnings("unchecked")
	protected final <E extends Throwable> E findCause(Throwable failure, Class<E> type) {
		while (failure != null) {
			if (type.isInstance(failure)) {
				return (E) failure;
			}
			failure = failure.getCause();
		}
		return null;
	}
}

//PortInUseFailureAnalyzer 負(fù)責(zé)解析 PortInUseException 異常
class PortInUseFailureAnalyzer extends AbstractFailureAnalyzer<PortInUseException>{
  ...
}

package com.andy.spring.boot.docker.exception;
public class CustomApplicationException extends RuntimeException {
    public CustomApplicationException(String msg){
        super(msg);
    }
}

package com.andy.spring.boot.docker.analyzer;
import com.andy.spring.boot.docker.exception.CustomApplicationException;
import org.springframework.boot.diagnostics.AbstractFailureAnalyzer;
import org.springframework.boot.diagnostics.FailureAnalysis;
public class CustomApplicationFailureAnalyzer extends AbstractFailureAnalyzer<CustomApplicationException> {
    @Override
    protected FailureAnalysis analyze(Throwable rootFailure, CustomApplicationException cause) {
        return new FailureAnalysis("Yeah, 自定義失敗分析器出現(xiàn)了...!",
                "Ummm... 啥都不做，刪庫跑路",
                cause);
    }
}

package com.andy.spring.boot.docker.service;
import com.andy.spring.boot.docker.exception.CustomApplicationException;
import org.springframework.stereotype.Component;
@Component
public class CacheService {
    public CacheService() {
        throw new CustomApplicationException("bean 初始化異常");
    }
}