设计模式【十】-责任链模式

解耦，每一阶段只需关心当前的处理，处理完后推送下一节点即可

定义统一接口及方法;

子类实现方法如execute，并定义成员变量nextNode;

应用时候，创建子类实例，并给实例赋值nextNode;

调用方法execute，execute内部自己方法执行完成后，执行nextNode的execute犯法.

package com.hz.design.responsechain.logger;


public abstract class AbstractLogger {

    public static final int DEBUG = 1;
    public static final int INFO = 2;
    public static final int ERROR = 3;

    protected int level;

    protected AbstractLogger nextLogger;

    public AbstractLogger() {
    }

    public AbstractLogger(int level) {
        this.level = level;
    }

    public void setNextLevel(AbstractLogger logger) {
        this.nextLogger = logger;
    }

    public void log(int level, String message) {
        if (this.level >= level) {
            this.write(message);
        }
        if (nextLogger != null) {
            nextLogger.log(level, message);
        }
    }

    protected abstract void write(String message);

}

package com.hz.design.responsechain.logger;


public class ErrorLogger extends AbstractLogger {

    public ErrorLogger(int level) {
        super(level);
    }

    @Override
    protected void write(String message) {
        System.out.println("Error log: " + message);
    }
}

package com.hz.design.responsechain.logger;


public class InfoLogger extends AbstractLogger {

    public InfoLogger(int level) {
        super(level);
    }

    @Override
    protected void write(String message) {
        System.out.println("Info log: " + message);
    }
}

package com.hz.design.responsechain.logger;


public class ConsoleLogger extends AbstractLogger {

    public ConsoleLogger(int level) {
        super(level);
    }

    @Override
    protected void write(String message) {
        System.out.println("Console log: " + message);
    }
}

package com.hz.design.responsechain;

import com.hz.design.responsechain.logger.AbstractLogger;
import com.hz.design.responsechain.logger.ConsoleLogger;
import com.hz.design.responsechain.logger.ErrorLogger;
import com.hz.design.responsechain.logger.InfoLogger;
import jdk.nashorn.internal.runtime.logging.DebugLogger;

import javax.sound.sampled.Line;


public class ResponseChainTest {

    private static AbstractLogger getChainOfLoggers() {
        ErrorLogger errorLogger = new ErrorLogger(AbstractLogger.ERROR);
        InfoLogger infoLogger = new InfoLogger(AbstractLogger.INFO);
        ConsoleLogger consoleLogger = new ConsoleLogger(AbstractLogger.DEBUG);

        errorLogger.setNextLevel(infoLogger);
        infoLogger.setNextLevel(consoleLogger);

        return errorLogger;
    }

    public static void main(String[] args) {

        AbstractLogger loggerChain = getChainOfLoggers();

        loggerChain.log(AbstractLogger.INFO, "debug: 打印日志");

    }
}

Connected to the target VM, address: '127.0.0.1:55228', transport: 'socket'
Error log: debug: 打印日志
Info log: debug: 打印日志
Disconnected from the target VM, address: '127.0.0.1:55228', transport: 'socket'

Process finished with exit code 0

菜鸟教程-责任链模式