@Resources, @Inject和@Autowired的區(qū)別是什么

這篇文章主要介紹“@Resources, @Inject和@Autowired的區(qū)別是什么”，在日常操作中，相信很多人在@Resources, @Inject和@Autowired的區(qū)別是什么問題上存在疑惑，小編查閱了各式資料，整理出簡(jiǎn)單好用的操作方法，希望對(duì)大家解答”@Resources, @Inject和@Autowired的區(qū)別是什么”的疑惑有所幫助！接下來，請(qǐng)跟著小編一起來學(xué)習(xí)吧！

@Resources

官方文檔里對(duì)@Resources的說明：

The @Resource annotation is part of the JSR-250 annotation collection and is packaged with Jakarta EE.

什么是JSR-250呢？訪問這個(gè)鏈接：https://id=250https://id=330

注入的優(yōu)先級(jí)：

1. Match by Type

2. Match by Qualifier

3. Match by Name

Match by Type

注意@Inject注入的最高優(yōu)先級(jí)方式為Match by Type，而非@Resource的Match by Name.

任意定義一個(gè)待注入的Component：

@Componentpublic class ArbitraryDependency {
    private final String label = "Arbitrary Dependency";
    public String toString() {
        return label;
    }}

使用@Inject注入：

@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(
  loader=AnnotationConfigContextLoader.class,
  classes=ApplicationContextTestInjectType.class)public class FieldInjectIntegrationTest {
    @Inject
    private ArbitraryDependency fieldInjectDependency;
    @Test
    public void givenInjectAnnotation_WhenOnField_ThenValidDependency(){
        assertNotNull(fieldInjectDependency);
        assertEquals("Arbitrary Dependency",
          fieldInjectDependency.toString());
    }}

Match by Qualifier

定義一個(gè)新的待注入組件：

public class AnotherArbitraryDependency extends ArbitraryDependency {
    private final String label = "Another Arbitrary Dependency";
    public String toString() {
        return label;
    }}

測(cè)試代碼：

@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(
  loader=AnnotationConfigContextLoader.class,
  classes=ApplicationContextTestInjectQualifier.class)public class FieldQualifierInjectIntegrationTest {
    @Inject
    private ArbitraryDependency defaultDependency;
    @Inject
    private ArbitraryDependency namedDependency;
    @Test
    public void givenInjectQualifier_WhenOnField_ThenDefaultFileValid(){
        assertNotNull(defaultDependency);
        assertEquals("Arbitrary Dependency",
          defaultDependency.toString());
    }
    @Test
    public void givenInjectQualifier_WhenOnField_ThenNamedFileValid(){
        assertNotNull(defaultDependency);
        assertEquals("Another Arbitrary Dependency",
          namedDependency.toString());
    }}

和之前@Resource的第一次試圖通過Match by Type注入一樣失敗，遇到異常：NoUniqueBeanDefinitionException

利用@Qualifier避免這個(gè)異常：

@Inject@Qualifier("defaultFile")private ArbitraryDependency defaultDependency;@Inject@Qualifier("namedFile")private ArbitraryDependency namedDependency;

Match by Name

public class YetAnotherArbitraryDependency extends ArbitraryDependency {
    private final String label = "Yet Another Arbitrary Dependency";
    public String toString() {
        return label;
    }}

消費(fèi)者代碼：

@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(
  loader=AnnotationConfigContextLoader.class,
  classes=ApplicationContextTestInjectName.class)public class FieldByNameInjectIntegrationTest {
    @Inject
    @Named("yetAnotherFieldInjectDependency")
    private ArbitraryDependency yetAnotherFieldInjectDependency;
    @Test
    public void givenInjectQualifier_WhenSetOnField_ThenDependencyValid(){
        assertNotNull(yetAnotherFieldInjectDependency);
        assertEquals("Yet Another Arbitrary Dependency",
          yetAnotherFieldInjectDependency.toString());
    }}

application context代碼：

@Configurationpublic class ApplicationContextTestInjectName {
    @Bean
    public ArbitraryDependency yetAnotherFieldInjectDependency() {
        ArbitraryDependency yetAnotherFieldInjectDependency =
          new YetAnotherArbitraryDependency();
        return yetAnotherFieldInjectDependency;
    }}

到此，關(guān)于“@Resources, @Inject和@Autowired的區(qū)別是什么”的學(xué)習(xí)就結(jié)束了，希望能夠解決大家的疑惑。理論與實(shí)踐的搭配能更好的幫助大家學(xué)習(xí)，快去試試吧！若想繼續(xù)學(xué)習(xí)更多相關(guān)知識(shí)，請(qǐng)繼續(xù)關(guān)注億速云網(wǎng)站，小編會(huì)繼續(xù)努力為大家?guī)砀鄬?shí)用的文章！