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slf4j: add slf4j integration module (OpenFeign#94)
Adds a new "slf4j" module. A few methods in Logger are now protected rather than package protected to allow access by Logger subclasses that aren't inner classes of Logger.
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‎CHANGES.md‎

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### Version 6.1.0
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* Add [SLF4J](http://www.slf4j.org/) integration
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### Version 6.0.1
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* Fix for BasicAuthRequestInterceptor when username and/or password are long.
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‎README.md‎

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@@ -141,6 +141,17 @@ Integration requires you to pass your ribbon client name as the host part of the
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MyService api = Feign.create(MyService.class, "https://myAppProd", new RibbonModule());
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```
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### SLF4J
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[SLF4JModule](https://github.com/Netflix/feign/tree/master/slf4j) allows directing Feign's logging to [SLF4J](http://www.slf4j.org/), allowing you to easily use a logging backend of your choice (Logback, Log4J, etc.)
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To use SLF4J with Feign, add both the SLF4J module and an SLF4J binding of your choice to your classpath. Then, configure Feign to use the Slf4jLogger:
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```java
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GitHub github = Feign.builder()
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.logger(new Slf4jLogger())
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.target(GitHub.class, "https://api.github.com");
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```
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### Decoders
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`Feign.builder()` allows you to specify additional configuration such as how to decode a response.
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@@ -198,3 +209,5 @@ GitHub github = Feign.builder()
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.logLevel(Logger.Level.FULL)
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.target(GitHub.class, "https://api.github.com");
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```
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The SLF4JModule (see above) may also be of interest.

‎build.gradle‎

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@@ -118,3 +118,18 @@ project(':feign-ribbon') {
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testCompile 'com.google.mockwebserver:mockwebserver:20130706'
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}
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}
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project(':feign-slf4j') {
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apply plugin: 'java'
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test {
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useTestNG()
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}
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dependencies {
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compile project(':feign-core')
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compile 'org.slf4j:slf4j-api:1.7.5'
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testCompile 'org.testng:testng:6.8.5'
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testCompile 'org.slf4j:slf4j-simple:1.7.5'
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}
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}

‎core/src/main/java/feign/Logger.java‎

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@@ -70,14 +70,13 @@ public static class ErrorLogger extends Logger {
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public static class JavaLogger extends Logger {
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final java.util.logging.Logger logger = java.util.logging.Logger.getLogger(Logger.class.getName());
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@Override void logRequest(String configKey, Level logLevel, Request request) {
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@Override protected void logRequest(String configKey, Level logLevel, Request request) {
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if (logger.isLoggable(java.util.logging.Level.FINE)) {
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super.logRequest(configKey, logLevel, request);
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}
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}
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@Override
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Response logAndRebufferResponse(String configKey, Level logLevel, Response response, long elapsedTime) throws IOException {
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@Override protected Response logAndRebufferResponse(String configKey, Level logLevel, Response response, long elapsedTime) throws IOException {
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if (logger.isLoggable(java.util.logging.Level.FINE)) {
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return super.logAndRebufferResponse(configKey, logLevel, response, elapsedTime);
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}
@@ -110,16 +109,14 @@ public String format(LogRecord record) {
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}
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public static class NoOpLogger extends Logger {
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@Override void logRequest(String configKey, Level logLevel, Request request) {
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@Override protected void logRequest(String configKey, Level logLevel, Request request) {
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}
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@Override
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Response logAndRebufferResponse(String configKey, Level logLevel, Response response, long elapsedTime) throws IOException {
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@Override protected Response logAndRebufferResponse(String configKey, Level logLevel, Response response, long elapsedTime) throws IOException {
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return response;
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}
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@Override
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protected void log(String configKey, String format, Object... args) {
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@Override protected void log(String configKey, String format, Object... args) {
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}
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}
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@@ -133,7 +130,7 @@ protected void log(String configKey, String format, Object... args) {
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*/
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protected abstract void log(String configKey, String format, Object... args);
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void logRequest(String configKey, Level logLevel, Request request) {
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protected void logRequest(String configKey, Level logLevel, Request request) {
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log(configKey, "---> %s %s HTTP/1.1", request.method(), request.url());
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if (logLevel.ordinal() >= Level.HEADERS.ordinal()) {
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@@ -160,7 +157,7 @@ void logRetry(String configKey, Level logLevel) {
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log(configKey, "---> RETRYING");
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}
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Response logAndRebufferResponse(String configKey, Level logLevel, Response response, long elapsedTime) throws IOException {
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protected Response logAndRebufferResponse(String configKey, Level logLevel, Response response, long elapsedTime) throws IOException {
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log(configKey, "<--- HTTP/1.1 %s %s (%sms)", response.status(), response.reason(), elapsedTime);
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if (logLevel.ordinal() >= Level.HEADERS.ordinal()) {
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return ioe;
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}
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static String methodTag(String configKey) {
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protected static String methodTag(String configKey) {
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return new StringBuilder().append('[').append(configKey.substring(0, configKey.indexOf('('))).append("] ").toString();
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}
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}

‎settings.gradle‎

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rootProject.name='feign'
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include 'core', 'sax', 'gson', 'jackson', 'jaxrs', 'ribbon', 'example-github', 'example-wikipedia'
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include 'core', 'sax', 'gson', 'jackson', 'jaxrs', 'ribbon', 'slf4j', 'example-github', 'example-wikipedia'
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rootProject.children.each { childProject ->
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childProject.name = 'feign-' + childProject.name

‎slf4j/README.md‎

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SLF4J
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===================
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This module allows directing Feign's logging to [SLF4J](http://www.slf4j.org/), allowing you to easily use a logging backend of your choice (Logback, Log4J, etc.)
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To use SLF4J with Feign, add both the SLF4J module and an SLF4J binding of your choice to your classpath. Then, configure Feign to use the Slf4jLogger:
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```java
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GitHub github = Feign.builder()
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.logger(new Slf4jLogger())
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.target(GitHub.class, "https://api.github.com");
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```

‎slf4j/src/main/java/feign/slf4j/Slf4jLogger.java‎

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/*
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* Copyright 2013 Netflix, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package feign.slf4j;
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import feign.Request;
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import feign.Response;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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import java.io.IOException;
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/**
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* Logs to SLF4J at the debug level, if the underlying logger has debug logging enabled. The underlying logger can
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* be specified at construction-time, defaulting to the logger for {@link feign.Logger}.
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*/
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public class Slf4jLogger extends feign.Logger {
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private final Logger logger;
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public Slf4jLogger() {
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this(feign.Logger.class);
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}
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public Slf4jLogger(Class<?> clazz) {
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this(LoggerFactory.getLogger(clazz));
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}
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public Slf4jLogger(String name) {
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this(LoggerFactory.getLogger(name));
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}
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Slf4jLogger(Logger logger) {
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this.logger = logger;
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}
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@Override protected void logRequest(String configKey, Level logLevel, Request request) {
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if (logger.isDebugEnabled()) {
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super.logRequest(configKey, logLevel, request);
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}
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}
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@Override protected Response logAndRebufferResponse(String configKey, Level logLevel, Response response, long elapsedTime) throws IOException {
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if (logger.isDebugEnabled()) {
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return super.logAndRebufferResponse(configKey, logLevel, response, elapsedTime);
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}
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return response;
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}
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@Override protected void log(String configKey, String format, Object... args) {
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// Not using SLF4J's support for parameterized messages (even though it would be more efficient) because it would
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// require the incoming message formats to be SLF4J-specific.
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logger.debug(String.format(methodTag(configKey) + format, args));
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}
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}

‎slf4j/src/test/java/feign/slf4j/ReflectionUtil.java‎

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/*
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* Copyright 2013 Netflix, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package feign.slf4j;
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import java.lang.reflect.Field;
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import java.lang.reflect.Method;
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/**
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* Lightweight approach to using reflection to bypass access restrictions for testing. If this class grows, it may be
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* better to use a testing library instead, such as Powermock.
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*/
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class ReflectionUtil {
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static void setStaticField(Class<?> declaringClass, String fieldName, Object fieldValue) throws Exception {
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Field field = declaringClass.getDeclaredField(fieldName);
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field.setAccessible(true);
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field.set(null, fieldValue);
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}
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static void invokeVoidNoArgMethod(Class<?> declaringClass, String methodName, Object instance) throws Exception {
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Method method = declaringClass.getDeclaredMethod(methodName);
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method.setAccessible(true);
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method.invoke(instance);
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}
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}

‎slf4j/src/test/java/feign/slf4j/SimpleLoggerUtil.java‎

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/*
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* Copyright 2013 Netflix, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package feign.slf4j;
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import org.slf4j.LoggerFactory;
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import org.slf4j.impl.SimpleLogger;
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import org.slf4j.impl.SimpleLoggerFactory;
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import java.io.File;
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/**
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* A testing utility to allow control over {@link SimpleLogger}. In some cases, reflection is used to bypass access
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* restrictions.
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*/
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class SimpleLoggerUtil {
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static void initialize(File file, String logLevel) throws Exception {
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System.setProperty(SimpleLogger.SHOW_THREAD_NAME_KEY, "false");
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System.setProperty(SimpleLogger.LOG_FILE_KEY, file.getAbsolutePath());
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System.setProperty(SimpleLogger.DEFAULT_LOG_LEVEL_KEY, logLevel);
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resetSlf4j();
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}
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static void resetToDefaults() throws Exception {
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System.clearProperty(SimpleLogger.SHOW_THREAD_NAME_KEY);
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System.clearProperty(SimpleLogger.LOG_FILE_KEY);
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System.clearProperty(SimpleLogger.DEFAULT_LOG_LEVEL_KEY);
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resetSlf4j();
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}
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private static void resetSlf4j() throws Exception {
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ReflectionUtil.setStaticField(SimpleLogger.class, "INITIALIZED", false);
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ReflectionUtil.invokeVoidNoArgMethod(SimpleLoggerFactory.class, "reset", LoggerFactory.getILoggerFactory());
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}
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}

‎slf4j/src/test/java/feign/slf4j/Slf4jLoggerTest.java‎

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/*
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* Copyright 2013 Netflix, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
14+
* limitations under the License.
15+
*/
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package feign.slf4j;
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18+
import feign.Feign;
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import feign.Logger;
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import feign.Request;
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import feign.RequestTemplate;
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import feign.Response;
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import feign.Util;
24+
import org.slf4j.LoggerFactory;
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import org.testng.annotations.AfterMethod;
26+
import org.testng.annotations.Test;
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28+
import java.io.File;
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import java.io.FileReader;
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import java.util.Collection;
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import java.util.Collections;
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33+
import static org.testng.Assert.assertEquals;
34+
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public class Slf4jLoggerTest {
36+
private static final String CONFIG_KEY = "someMethod()";
37+
private static final Request REQUEST =
38+
new RequestTemplate().method("GET").append("http://api.example.com").request();
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private static final Response RESPONSE =
40+
Response.create(200, "OK", Collections.<String, Collection<String>>emptyMap(), new byte[0]);
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private File logFile;
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private Slf4jLogger logger;
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@AfterMethod
46+
void tearDown() throws Exception {
47+
SimpleLoggerUtil.resetToDefaults();
48+
logFile.delete();
49+
}
50+
51+
@Test public void useFeignLoggerByDefault() throws Exception {
52+
initializeSimpleLogger("debug");
53+
logger = new Slf4jLogger();
54+
logger.log(CONFIG_KEY, "This is my message");
55+
assertLoggedMessages("DEBUG feign.Logger - [someMethod] This is my message\n");
56+
}
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58+
@Test public void useLoggerByNameIfRequested() throws Exception {
59+
initializeSimpleLogger("debug");
60+
logger = new Slf4jLogger("named.logger");
61+
logger.log(CONFIG_KEY, "This is my message");
62+
assertLoggedMessages("DEBUG named.logger - [someMethod] This is my message\n");
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}
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@Test public void useLoggerByClassIfRequested() throws Exception {
66+
initializeSimpleLogger("debug");
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logger = new Slf4jLogger(Feign.class);
68+
logger.log(CONFIG_KEY, "This is my message");
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assertLoggedMessages("DEBUG feign.Feign - [someMethod] This is my message\n");
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}
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@Test public void useSpecifiedLoggerIfRequested() throws Exception {
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initializeSimpleLogger("debug");
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logger = new Slf4jLogger(LoggerFactory.getLogger("specified.logger"));
75+
logger.log(CONFIG_KEY, "This is my message");
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assertLoggedMessages("DEBUG specified.logger - [someMethod] This is my message\n");
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}
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@Test public void logOnlyIfDebugEnabled() throws Exception {
80+
initializeSimpleLogger("info");
81+
logger = new Slf4jLogger();
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logger.log(CONFIG_KEY, "A message with %d formatting %s.", 2, "tokens");
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logger.logRequest(CONFIG_KEY, Logger.Level.BASIC, REQUEST);
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logger.logAndRebufferResponse(CONFIG_KEY, Logger.Level.BASIC, RESPONSE, 273);
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assertLoggedMessages("");
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}
87+
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@Test public void logRequestsAndResponses() throws Exception {
89+
initializeSimpleLogger("debug");
90+
logger = new Slf4jLogger();
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logger.log(CONFIG_KEY, "A message with %d formatting %s.", 2, "tokens");
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logger.logRequest(CONFIG_KEY, Logger.Level.BASIC, REQUEST);
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logger.logAndRebufferResponse(CONFIG_KEY, Logger.Level.BASIC, RESPONSE, 273);
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assertLoggedMessages(
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"DEBUG feign.Logger - [someMethod] A message with 2 formatting tokens.\n" +
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"DEBUG feign.Logger - [someMethod] ---> GET http://api.example.com HTTP/1.1\n" +
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"DEBUG feign.Logger - [someMethod] <--- HTTP/1.1 200 OK (273ms)\n"
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);
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}
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private void initializeSimpleLogger(String logLevel) throws Exception {
102+
logFile = File.createTempFile(getClass().getName(), ".log");
103+
SimpleLoggerUtil.initialize(logFile, logLevel);
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}
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private void assertLoggedMessages(String expectedMessages) throws Exception {
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assertEquals(Util.toString(new FileReader(logFile)), expectedMessages);
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}
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}

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