Groovy动态语言 运行在JVM中的动态语言 可以方便的处理业务逻辑变化大的业务

				class SafeNavigationTest extends GroovyTestCase {
				
				    void testNullNavigation() {
				        def x = null
				        def y = x?.bar
				
				        assert y == null
				    }
				
				    void testNormalPropertyNavigation() {
				        def x = ['a':456, 'foo':['bar':123, 'x':456], 'z':99]
				        
				        def y = x?.foo?.bar
				        
				        println("found y ${x?.foo?.bar}")
				        
				        assert y == 123
				    }
				
				    void testNullPropertyNavigation() {
				        def x = null
				        
				        def y = x?.foo?.bar
				        
				        assert y == null
				
				
				        def java.awt.Color color = null
				        def a = color?.alpha
				        assert a == null
				
				    }
				    
				    void testNormalMethodCall() {
				        def x = 1234
				        
				        def y = x?.toString()
				        
				        assert y == "1234"
				    }
				
				    void testNullMethodCall() {
				        def x = null
				        
				        def y = x?.toString()
				        
				        assert y == null
				    }
				
				}