Shiro Filter中利用Callable和Runnable的委派模式

Callable模式

package com.wjz.core;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;

public class SubjectCallable<V> implements Callable<V> {
    
    private Callable<V> delegate;
    
    private List<V> resouces;
    
    public SubjectCallable(Callable<V> delegate) {
        this.delegate = delegate;
    }
    
    @Override
    public V call() throws Exception {
        preCall();
        V v = doCall(this.delegate);
        postCall(v);
        return v;
    }

    private void add(V v) {
        resouces.add(v);
    }

    private void postCall(V v) {
        if (v == null) {
            throw new RuntimeException();
        }
        add(v);
    }

    private void preCall() {
        if (resouces == null) {
            resouces = new ArrayList<V>();
        }
    }

    private V doCall(Callable<V> target) throws Exception {
        return target.call();
    }

}

Runnable模式

package com.wjz.core;

public class SubjectRunnable<V> implements Runnable {
    
    private Runnable delegate;

    @Override
    public void run() {
        doRun(this.delegate);
    }

    private void doRun(Runnable target) {
        target.run();
    }

}

Demo

package com.wjz.core;

import java.util.concurrent.Callable;

public class DelegatingSubject {

    public <V> V execute(Callable<V> delegate) {
        Callable<V> associated = associateWith(delegate);
        try {
            return associated.call();
        } catch (Exception e) {
            throw new RuntimeException();
        }
    }

    private <V> Callable<V> associateWith(Callable<V> delegate) {
        return new SubjectCallable<>(delegate);
    }
}