javac的Resolve类解读

方法1：isInitializer()

/** An environment is an "initializer" if it is a constructor or
     *  an instance initializer.
     */
    static boolean isInitializer(Env<AttrContext> env) {
        Symbol owner = env.info.scope.owner;
        return owner.isConstructor() ||
                owner.owner.kind == TYP &&
                (owner.kind == VAR || owner.kind == MTH && (owner.flags() & BLOCK) != 0) &&
                (owner.flags() & STATIC) == 0;
    }

根据如上方法可以看出检查了如下三种情况的initializer：

public class TestInitializer {

	TestInitializer() { // constructor

	}

	int a = 2;   // instance variable initializer

	{  // instance initializer block
		a = 3;
	}
}

方法2：isAccessable()

/** Is class accessible in given environment?
     *  @param env    The current environment.
     *  @param c      The class whose accessibility is checked.
     */
    public boolean isAccessible(Env<AttrContext> env, TypeSymbol c) {
        return isAccessible(env, c, false);
    }

    public boolean isAccessible(Env<AttrContext> env, TypeSymbol c, boolean checkInner) {
        boolean isAccessible = false;
        switch ((short)(c.flags() & AccessFlags)) {
            case PRIVATE:
                isAccessible =
                    env.enclClass.sym.outermostClass() ==
                    c.owner.outermostClass();
                break;
            case 0:
                isAccessible =
                    env.toplevel.packge == c.owner // fast special case
                    ||
                    env.toplevel.packge == c.packge()
                    ||
                    // Hack: this case is added since synthesized default constructors
                    // of anonymous classes should be allowed to access
                    // classes which would be inaccessible otherwise.
                    env.enclMethod != null &&
                    (env.enclMethod.mods.flags & ANONCONSTR) != 0; // anonconstr 匿名构造函数
                break;
            default: // error recovery
            case PUBLIC:
                isAccessible = true;
                break;
            case PROTECTED:
                isAccessible =
                    env.toplevel.packge == c.owner // fast special case
                    ||
                    env.toplevel.packge == c.packge()
                    ||
                    isInnerSubClass(env.enclClass.sym, c.owner);
                break;
        }
        return (checkInner == false || c.type.getEnclosingType() == Type.noType) ?
            isAccessible :
            isAccessible && isAccessible(env, c.type.getEnclosingType(), checkInner);
    }　　

检查的是TypeSymbol是否在某个Env中被访问到，能否访问到最终还要看Java的权限控制符public、protected、default和private。

另外需要知道的是只有Inner Class才可以为protected和private进行修饰。重点看一下protected修饰的类的逻辑。

public class Test {

	protected class D {
		public D() {
			// TODO Auto-generated constructor stub
		}
	}
}

class A { // only public, abstract & final are permitted
	// protected class D{}
}

public class TestAccessible {

	protected class B { // public,protected,private are permitted

	}

	public void method() {
		new A();  // 走env.toplevel.packge == c.owner
		new B();  // 走env.toplevel.packge == c.packge
	}

	class C extends Test{
		public void method3(){
			new D(); // 走isInnerSubClass(env.enclClass.sym,c.owner)
		}
	}

}