import org.springframework.expression.spel.support.StandardTypeLocator; //导入依赖的package包/类
@Test
	public void testImports() throws EvaluationException {
		StandardTypeLocator locator = new StandardTypeLocator();
		assertEquals(Integer.class,locator.findType("java.lang.Integer"));
		assertEquals(String.class,locator.findType("java.lang.String"));

		List<String> prefixes = locator.getImportPrefixes();
		assertEquals(1,prefixes.size());
		assertTrue(prefixes.contains("java.lang"));
		assertFalse(prefixes.contains("java.util"));

		assertEquals(Boolean.class,locator.findType("Boolean"));
		// currently does not know about java.util by default
//		assertEquals(java.util.List.class,locator.findType("List"));

		try {
			locator.findType("URL");
			fail("Should have failed");
		} catch (EvaluationException ee) {
			SpelEvaluationException sEx = (SpelEvaluationException)ee;
			assertEquals(SpelMessage.TYPE_NOT_FOUND,sEx.getMessageCode());
		}
		locator.registerImport("java.net");
		assertEquals(java.net.URL.class,locator.findType("URL"));
	}
 

import org.springframework.expression.spel.support.StandardTypeLocator; //导入依赖的package包/类
@Test
public void testResolvingList() throws Exception {
	StandardEvaluationContext context = TestScenarioCreator.getTestEvaluationContext();
	try {
		assertFalse(parser.parseExpression("T(List)!=null").getValue(context, Boolean.class));
		fail("should have failed to find List");
	} catch (EvaluationException ee) {
		// success - List not found
	}
	((StandardTypeLocator) context.getTypeLocator()).registerImport("java.util");
	assertTrue(parser.parseExpression("T(List)!=null").getValue(context, Boolean.class));
}
 

import org.springframework.expression.spel.support.StandardTypeLocator; //导入依赖的package包/类
public Object evaluate(String value, BeanExpressionContext evalContext) throws BeansException {
	if (!StringUtils.hasLength(value)) {
		return value;
	}
	try {
		Expression expr = this.expressionCache.get(value);
		if (expr == null) {
			expr = this.expressionParser.parseExpression(value, this.beanExpressionParserContext);
			this.expressionCache.put(value, expr);
		}
		StandardEvaluationContext sec = this.evaluationCache.get(evalContext);
		if (sec == null) {
			sec = new StandardEvaluationContext();
			sec.setRootObject(evalContext);
			sec.addPropertyAccessor(new BeanExpressionContextAccessor());
			sec.addPropertyAccessor(new BeanFactoryAccessor());
			sec.addPropertyAccessor(new MapAccessor());
			sec.addPropertyAccessor(new EnvironmentAccessor());
			sec.setBeanResolver(new BeanFactoryResolver(evalContext.getBeanFactory()));
			sec.setTypeLocator(new StandardTypeLocator(evalContext.getBeanFactory().getBeanClassLoader()));
			ConversionService conversionService = evalContext.getBeanFactory().getConversionService();
			if (conversionService != null) {
				sec.setTypeConverter(new StandardTypeConverter(conversionService));
			}
			customizeEvaluationContext(sec);
			this.evaluationCache.put(evalContext, sec);
		}
		return expr.getValue(sec);
	}
	catch (Exception ex) {
		throw new BeanExpressionException("Expression parsing failed", ex);
	}
}