设计模式

异常处理方法

package com.whalefall.learncases.exception;

import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import java.sql.SQLException;

/**
 * @author WhaleFall
 * @create 2022-05-28 10:41
 * codes copy from => https://spring.io/blog/2013/11/01/exception-handling-in-spring-mvc
 */
@Slf4j
@ControllerAdvice// 指定为全局异常处理
public class ExceptionHandlingController {

    // Specify name of a specific view that will be used to display the error:
    @ExceptionHandler(SQLException.class)
    public String databaseError() {
        // Nothing to do.  Returns the logical view name of an error page, passed
        // to the view-resolver(s) in usual way.
        // Note that the exception is NOT available to this view (it is not added
        // to the model) but see "Extending ExceptionHandlerExceptionResolver"
        // below.
        return "databaseError";
    }

    // Total control - setup a model and return the view name yourself. Or
    // consider subclassing ExceptionHandlerExceptionResolver (see below).
    @ExceptionHandler(Exception.class)
    public ModelAndView handleError(HttpServletRequest req, Exception ex) {
        log.error("Request: " + req.getRequestURL() + " raised " + ex);

        ModelAndView mav = new ModelAndView();
        mav.addObject("exception", ex);
        mav.addObject("url", req.getRequestURL());
        mav.setViewName("error");
        return mav;
    }

}

基于接口设计

接口类

package com.whalefall.learncases.design;

/**
 * @author WhaleFall
 * @create 2022-07-25 19:21
 */
public interface IService {
    boolean doService();

    boolean doServiceBefore();

    boolean doServiceAfter();

    void doLog();
}

接口实现类

package com.whalefall.learncases.design;

import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

/**
 * @author WhaleFall
 * @create 2022-07-24 6:34
 */
@Slf4j
@Component
public class AService implements IService {
    @Override
    public boolean doService() {
        log.info("do A service");
        if (true)
            throw new RuntimeException("Exception msg1");
        return true;
    }

    @Override
    public boolean doServiceBefore() {
        return false;
    }

    @Override
    public boolean doServiceAfter() {
        return false;
    }

    @Override
    public void doLog() {
        if (true)
            throw new RuntimeException("Exception msg2");
        log.error("A1 do log");
    }
}

核心流程封装

可以使用单例设计模式

方法1单例设计模式

package com.whalefall.learncases.design;

import lombok.extern.slf4j.Slf4j;

import javax.validation.constraints.NotNull;
import java.util.function.Consumer;

/**
 * @author WhaleFall
 * @create 2022-07-24 6:26
 */
@Slf4j
public class SProcessService {
    private SProcessService() {

    }

    private static class SProcessServiceHolder {
        private static final SProcessService INSTANCE = new SProcessService();
    }
    
    public static SProcessService getInstance() {
        return SProcessServiceHolder.INSTANCE;
    } 
    
    public boolean handle(IService service, Consumer<Exception> exceptionConsumer) {
        serviceBefore(service);
        service(service, exceptionConsumer);
        serviceAfter(service);
        log(service, exceptionConsumer);
        return true;
    }

    private void serviceAfter(@NotNull IService service) {
        service.doServiceAfter();
    }

    private void serviceBefore(@NotNull IService service) {
        service.doServiceBefore();
    }

    private void service(@NotNull IService service, Consumer<Exception> exceptionConsumer) {
        try {
            service.doService();
        } catch (Exception e1) {
            exceptionConsumer.accept(e1);
            throw e1;
        }
    }

    private void log(@NotNull IService service, Consumer<Exception> exceptionConsumer) {
        try {
            service.doLog();
        } catch (Exception e2) {
            log.error("failed do log");
            exceptionConsumer.accept(e2);
        }
    }
}

方法2 注入容器中

package com.whalefall.learncases.design;

import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

import javax.validation.constraints.NotNull;
import java.util.function.Consumer;

/**
 * @author WhaleFall
 * @create 2022-07-24 6:26
 */
@Component
@Slf4j
public class ProcessService {
    
    public boolean handle(IService service, Consumer<Exception> exceptionConsumer) {
        serviceBefore(service);
        service(service, exceptionConsumer);
        serviceAfter(service);
        log(service, exceptionConsumer);
        return true;
    }

    private void serviceAfter(@NotNull IService service) {
        service.doServiceAfter();
    }

    private void serviceBefore(@NotNull IService service) {
        service.doServiceBefore();
    }

    private void service(@NotNull IService service, Consumer<Exception> exceptionConsumer) {
        try {
            service.doService();
        } catch (Exception e1) {
            exceptionConsumer.accept(e1);
            throw e1;
        }
    }

    private void log(@NotNull IService service, Consumer<Exception> exceptionConsumer) {
        try {
            service.doLog();
        } catch (Exception e2) {
            log.error("failed do log");
            exceptionConsumer.accept(e2);
        }
    }
}

调用案例

package com.whalefall.learncases.design;

import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author WhaleFall
 * @create 2022-07-24 6:37
 */
@RestController
@Slf4j
public class ControllerA {

    private IService service;

    private ProcessService processService;

    public ControllerA(IService service, ProcessService processService) {
        this.service = service;
        this.processService = processService;
    }

    @GetMapping("/testA")
    public boolean getA(){
       return processService.handle(service, e -> log.error(e.getMessage(), e));
    }
}

完整代码

DDD

实体对象不能直接赋值，领域对象不能直接new出来，应该使用工厂方法，建造者模式来实现。

协议

本作品代码部分采用 Apache 2.0协议进行许可。遵循许可的前提下，你可以自由地对代码进行修改，再发布，可以将代码用作商业用途。但要求你：
- 署名：在原有代码和衍生代码中，保留原作者署名及代码来源信息。
- 保留许可证：在原有代码和衍生代码中，保留Apache 2.0协议文件。
本作品文档部分采用知识共享署名 4.0 国际许可协议进行许可。遵循许可的前提下，你可以自由地共享，包括在任何媒介上以任何形式复制、发行本作品，亦可以自由地演绎、修改、转换或以本作品为基础进行二次创作。但要求你：
- 署名：应在使用本文档的全部或部分内容时候，注明原作者及来源信息。
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异常处理 方法​

基于接口设计​

DDD​

异常处理方法

基于接口设计

DDD