ognl_ognl用于什么_java(9)

（2）如果获取的get方法不为空，则通过java反射执行该方法。也就是调用了person中的getName（）方法获取值，其实到这里就分析完成了。后面分析一下getGetMethod是怎么获取相应的方法的。

11、getGetMethod（）代码：

 public static final Method getGetMethod(OgnlContext context, Class targetClass, String propertyName) throws IntrospectionException, OgnlException
    {
        Method              result = null;
        PropertyDescriptor  pd = getPropertyDescriptor(targetClass, propertyName);

        if (pd == null) {
            List        methods = getDeclaredMethods(targetClass, propertyName, false /* find 'get' methods */);

            if (methods != null) {
                for (int i = 0, icount = methods.size(); i < icount; i++) {
                    Method      m = (Method)methods.get(i);
                    Class[]     mParameterTypes = getParameterTypes(m);

                    if (mParameterTypes.length == 0) {
                        result = m;
                        break;
                    }
                }
            }
        } else {
            result = pd.getReadMethod();
        }
        return result;
    }

注释：（1）getPropertyDescriptor获取和属性name相关的方法，并且保存到PropertyDescriptor对象中。

PropertyDescriptor类表示JavaBean类通过存储器导出一个属性。主要方法：

<1、getPropertyType()，获得属性的Class对象。

<2、getReadMethod()，获得用于读取属性值的方法；getWriteMethod()，获得用于写入属性值的方法。ognl

<3、hashCode()，获取对象的哈希值。

<4、setReadMethod(MethodreadMethod)，设置用于读取属性值的方法；setWriteMethod(MethodwriteMethod)，设置用于写入属性值的方法；

(2)PropertyDescriptor获取对象后，如果不为空则调用pd.getReadMethod()方法：

 public synchronized Method getReadMethod() {
	Method readMethod = getReadMethod0();
	if (readMethod == null) {
	    Class cls = getClass0();
	    if (cls == null || (readMethodName == null && readMethodRef == null)) {
		// The read method was explicitly set to null.
		return null;
	    }
	    if (readMethodName == null) {
		Class type = getPropertyType0();
		if (type == boolean.class || type == null) {
		    readMethodName = "is" + getBaseName();
		} else {
		    readMethodName = "get" + getBaseName();
		}
	    }
	    
	    // Since there can be multiple write methods but only one getter
	    // method, find the getter method first so that you know what the
	    // property type is.  For booleans, there can be "is" and "get"
	    // methods.  If an "is" method exists, this is the official
	    // reader method so look for this one first.
	    readMethod = Introspector.findMethod(cls, readMethodName, 0);
	    if (readMethod == null) {
		readMethodName = "get" + getBaseName();
		readMethod = Introspector.findMethod(cls, readMethodName, 0);
	    }
	    try {
		setReadMethod(readMethod);
	    } catch (IntrospectionException ex) {
		// fall
	    }
	}
	return readMethod;
    }

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