junit测试

导入junit-4.8.2.jar

package test;

import org.junit.*;

import java.util.Optional;

public class ATest {

    /**
     * 1、@BeforeClass修饰的方法会在所有方法被调用前被执行
     * 而且该方法是静态的，所有当测试类被加载后接着就会运行它
     * 而且在内存中它只会存在一份实例，它比较适合加载配置文件
     * 2、@AfterClass所修饰的方法通常用来对资源的清理，如关闭数据库的连接
     * 3、@Before和@After会在每个测试方法的前后各执行一次
     */

    @BeforeClass
    public static void setUpBeforeClass() throws Exception {
        System.out.println("this is @BeforeClass ...");
    }

    @AfterClass
    public static void tearDownAfterClass() throws Exception {
        System.out.println("this is @AfterClass ...");
    }

    @Before
    public void setUp() throws Exception {
        System.out.println("this is @Before ...");
    }

    @After
    public void tearDown() throws Exception {
        System.out.println("this is @After ...");
    }

    @Test
    public void test1() {
        System.out.println("this is test1 ...");
        String userName = "Green";
        Optional<String> userNameOpt = Optional.of(userName);
        Assert.assertEquals(userName, userNameOpt.get());
    }

    @Test
    public void test2() {
        System.out.println("this is test2 ...");
        ATest aTest = new ATest();
        Integer value1 = null;
        Integer value2 = new Integer(10);

        // Optional.ofNullable - 允许传递为 null 参数
        Optional<Integer> a = Optional.ofNullable(value1);
        // Optional.of - 如果传递的参数是 null，抛出异常 NullPointerException
        Optional<Integer> b = Optional.of(value2);
        System.out.println(aTest.sum(a,b));
    }

    public Integer sum(Optional<Integer> a, Optional<Integer> b){
        // Optional.isPresent - 判断值是否存在
        System.out.println("第一个参数值存在: " + a.isPresent());
        System.out.println("第二个参数值存在: " + b.isPresent());

        //Integer value = a.get(); //值不存在所以会报错java.util.NoSuchElementException: No value present

        // Optional.orElse - 如果值存在，返回它，否则返回默认值
        Integer value1 = a.orElse(new Integer(1));

        //Optional.get - 获取值，值需要存在
        Integer value2 = b.get();
        return value1 + value2;
    }
}

 

执行结果

this is @BeforeClass ...
this is @Before ...
this is test1 ...
this is @After ...
this is @Before ...
this is test2 ...
第一个参数值存在: false
第二个参数值存在: true
11
this is @After ...
this is @AfterClass ...