MethodArea.java

package minijvm.engine;

import java.util.HashMap;
import java.util.Map;

import minijvm.clz.ClassFile;
import minijvm.constant.MethodRefInfo;
import minijvm.loader.ClassFileLoader;
import minijvm.method.Method;

public class MethodArea {
	
	public static final MethodArea instance = new MethodArea();
	
	/**
	 * 注意：我们做了极大的简化， ClassLoader 只有一个， 实际JVM中的ClassLoader,是一个双亲委托的模型
	 */
	
	private ClassFileLoader clzLoader = null;
	
	Map<String,ClassFile> map = new HashMap<String,ClassFile>();
	
	private MethodArea(){		
	}
	
	public static MethodArea getInstance(){
		return instance;
	}
	
	public void setClassFileLoader(ClassFileLoader clzLoader){
		this.clzLoader = clzLoader;
	}
	
	public Method getMainMethod(String className) throws ClassNotFoundException{
		
		ClassFile clzFile = this.findClassFile(className);
		
		return clzFile.getMainMethod();
	}
	
	
	public  ClassFile findClassFile(String className) {
		
		if(map.get(className) != null){
			return map.get(className);
		}
		// 看来该class 文件还没有load过
		ClassFile clzFile = null;
        try {
            clzFile = this.clzLoader.loadClass(className);
        } catch (ClassNotFoundException e) {
            throw new RuntimeException("没有找到对应类文件");
        }
		
		map.put(className, clzFile);
		
		return clzFile;
		
	}
	
	
	public Method getMethod(String className, String methodName, String paramAndReturnType){
		
		return null;
	}
	
	
	public Method getMethod(MethodRefInfo methodRef) {		
		ClassFile clz = this.findClassFile(methodRef.getClassName());
		Method m = clz.getMethod(methodRef.getMethodName(), methodRef.getParamAndReturnType());
		if (m == null) {
		    throw new RuntimeException("找不到方法：" + methodRef.getMethodName());
		}
		return m;
			
	}
}