spring cloud中FeignClientBuilder的用法

这篇文章主要讲解了"spring cloud中FeignClientBuilder的用法"，文中的讲解内容简单清晰，易于学习与理解，下面请大家跟着小编的思路慢慢深入，一起来研究和学习"spring cloud中FeignClientBuilder的用法"吧！

序

本文主要研究一下spring cloud的FeignClientBuilder

FeignClientBuilder

spring-cloud-openfeign-core-2.2.0.M1-sources.jar!/org/springframework/cloud/openfeign/FeignClientBuilder.java

public class FeignClientBuilder {        private final ApplicationContext applicationContext;        public FeignClientBuilder(final ApplicationContext applicationContext) {                this.applicationContext = applicationContext;        }        public  Builder forType(final Class type, final String name) {                return new Builder<>(this.applicationContext, type, name);        }        /**         * Builder of feign targets.         *         * @param  type of target         */        public static final class Builder {                private FeignClientFactoryBean feignClientFactoryBean;                private Builder(final ApplicationContext applicationContext, final Class type,                                final String name) {                        this.feignClientFactoryBean = new FeignClientFactoryBean();                        this.feignClientFactoryBean.setApplicationContext(applicationContext);                        this.feignClientFactoryBean.setType(type);                        this.feignClientFactoryBean.setName(FeignClientsRegistrar.getName(name));                        this.feignClientFactoryBean.setContextId(FeignClientsRegistrar.getName(name));                        // preset default values - these values resemble the default values on the                        // FeignClient annotation                        this.url("").path("").decode404(false).fallback(void.class)                                        .fallbackFactory(void.class);                }                public Builder url(final String url) {                        this.feignClientFactoryBean.setUrl(FeignClientsRegistrar.getUrl(url));                        return this;                }                public Builder contextId(final String contextId) {                        this.feignClientFactoryBean.setContextId(contextId);                        return this;                }                public Builder path(final String path) {                        this.feignClientFactoryBean.setPath(FeignClientsRegistrar.getPath(path));                        return this;                }                public Builder decode404(final boolean decode404) {                        this.feignClientFactoryBean.setDecode404(decode404);                        return this;                }                public Builder fallback(final Class fallback) {                        FeignClientsRegistrar.validateFallback(fallback);                        this.feignClientFactoryBean.setFallback(fallback);                        return this;                }                public Builder fallbackFactory(final Class fallbackFactory) {                        FeignClientsRegistrar.validateFallbackFactory(fallbackFactory);                        this.feignClientFactoryBean.setFallbackFactory(fallbackFactory);                        return this;                }                /**                 * @param  the target type of the Feign client to be created                 * @return the created Feign client                 */                public  T build() {                        return this.feignClientFactoryBean.getTarget();                }        }}

• FeignClientBuilder提供了forType静态方法用于创建Builder；Builder的构造器创建了FeignClientFactoryBean，其build方法使用FeignClientFactoryBean的getTarget()来创建目标feign client

实例

public class FeignClientBuilderTests {        @Rule        public ExpectedException thrown = ExpectedException.none();        private FeignClientBuilder feignClientBuilder;        private ApplicationContext applicationContext;        private static Object getDefaultValueFromFeignClientAnnotation(                        final String methodName) {                final Method method = ReflectionUtils.findMethod(FeignClient.class, methodName);                return method.getDefaultValue();        }        private static void assertFactoryBeanField(final FeignClientBuilder.Builder builder,                        final String fieldName, final Object expectedValue) {                final Field factoryBeanField = ReflectionUtils                                .findField(FeignClientBuilder.Builder.class, "feignClientFactoryBean");                ReflectionUtils.makeAccessible(factoryBeanField);                final FeignClientFactoryBean factoryBean = (FeignClientFactoryBean) ReflectionUtils                                .getField(factoryBeanField, builder);                final Field field = ReflectionUtils.findField(FeignClientFactoryBean.class,                                fieldName);                ReflectionUtils.makeAccessible(field);                final Object value = ReflectionUtils.getField(field, factoryBean);                assertThat(value).as("Expected value for the field '" + fieldName + "':")                                .isEqualTo(expectedValue);        }        @Before        public void setUp() {                this.applicationContext = Mockito.mock(ApplicationContext.class);                this.feignClientBuilder = new FeignClientBuilder(this.applicationContext);        }        @Test        public void safetyCheckForNewFieldsOnTheFeignClientAnnotation() {                final List methodNames = new ArrayList();                for (final Method method : FeignClient.class.getMethods()) {                        methodNames.add(method.getName());                }                methodNames.removeAll(                                Arrays.asList("annotationType", "value", "serviceId", "qualifier",                                                "configuration", "primary", "equals", "hashCode", "toString"));                Collections.sort(methodNames);                // If this safety check fails the Builder has to be updated.                // (1) Either a field was removed from the FeignClient annotation and so it has to                // be removed                // on this builder class.                // (2) Or a new field was added and the builder class has to be extended with this                // new field.                assertThat(methodNames).containsExactly("contextId", "decode404", "fallback",                                "fallbackFactory", "name", "path", "url");        }        @Test        public void forType_preinitializedBuilder() {                // when:                final FeignClientBuilder.Builder builder = this.feignClientBuilder                                .forType(FeignClientBuilderTests.class, "TestClient");                // then:                assertFactoryBeanField(builder, "applicationContext", this.applicationContext);                assertFactoryBeanField(builder, "type", FeignClientBuilderTests.class);                assertFactoryBeanField(builder, "name", "TestClient");                assertFactoryBeanField(builder, "contextId", "TestClient");                // and:                assertFactoryBeanField(builder, "url",                                getDefaultValueFromFeignClientAnnotation("url"));                assertFactoryBeanField(builder, "path",                                getDefaultValueFromFeignClientAnnotation("path"));                assertFactoryBeanField(builder, "decode404",                                getDefaultValueFromFeignClientAnnotation("decode404"));                assertFactoryBeanField(builder, "fallback",                                getDefaultValueFromFeignClientAnnotation("fallback"));                assertFactoryBeanField(builder, "fallbackFactory",                                getDefaultValueFromFeignClientAnnotation("fallbackFactory"));        }        @Test        public void forType_allFieldsSetOnBuilder() {                // when:                final FeignClientBuilder.Builder builder = this.feignClientBuilder                                .forType(FeignClientBuilderTests.class, "TestClient").decode404(true)                                .fallback(Object.class).fallbackFactory(Object.class).path("Path/")                                .url("Url/");                // then:                assertFactoryBeanField(builder, "applicationContext", this.applicationContext);                assertFactoryBeanField(builder, "type", FeignClientBuilderTests.class);                assertFactoryBeanField(builder, "name", "TestClient");                // and:                assertFactoryBeanField(builder, "url", "http://Url/");                assertFactoryBeanField(builder, "path", "/Path");                assertFactoryBeanField(builder, "decode404", true);                assertFactoryBeanField(builder, "fallback", Object.class);                assertFactoryBeanField(builder, "fallbackFactory", Object.class);        }        @Test        public void forType_build() {                // given:                Mockito.when(this.applicationContext.getBean(FeignContext.class))                                .thenThrow(new ClosedFileSystemException()); // throw an unusual exception                                                                                                                                // in the                                                                                                                                // FeignClientFactoryBean                final FeignClientBuilder.Builder builder = this.feignClientBuilder                                .forType(TestClient.class, "TestClient");                // expect: 'the build will fail right after calling build() with the mocked                // unusual exception'                this.thrown.expect(Matchers.isA(ClosedFileSystemException.class));                builder.build();        }}

• FeignClientBuilderTests验证了safetyCheckForNewFieldsOnTheFeignClientAnnotation、forType_preinitializedBuilder、forType_allFieldsSetOnBuilder、forType_build

小结

FeignClientBuilder提供了forType静态方法用于创建Builder；Builder的构造器创建了FeignClientFactoryBean，其build方法使用FeignClientFactoryBean的getTarget()来创建目标feign client

感谢各位的阅读，以上就是"spring cloud中FeignClientBuilder的用法"的内容了，经过本文的学习后，相信大家对spring cloud中FeignClientBuilder的用法这一问题有了更深刻的体会，具体使用情况还需要大家实践验证。这里是，小编将为大家推送更多相关知识点的文章，欢迎关注！