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---
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title: "Microservices Self-Registration Pattern in Java with Spring Boot and Eureka"
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shortTitle: Microservices Pattern - Self-Registration
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description: "Dynamically register and discover Java microservices using Spring Boot and Eureka for resilient, scalable communication."
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category: Service Discovery
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language: en
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tag:
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- Microservices
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- Self-Registration
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- Service Discovery
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- Eureka
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- Spring Boot
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- Spring Cloud
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- Java
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- Dynamic Configuration
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- Resilience
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---
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## Intent of Microservices Self-Registration Pattern
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The intent of the Self-Registration pattern is to enable microservices to automatically announce their presence and location to a central registry (like Eureka) upon startup, simplifying service discovery and allowing other services to find and communicate with them without manual configuration or hardcoded addresses. This promotes dynamic and resilient microservices architectures.
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## Example
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In this example we have implemented two microservices with utmost simplicity, Greeting Service and Context Service, to provide greeting and contextual information respectively.
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## When to use Microservices Self-Registration Pattern
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- **Dynamic Environments:** When your microservices are frequently deployed, scaled up or down, or their network locations (IP addresses and ports) change often. This is common in cloud-based or containerized environments (like Docker and Kubernetes).
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- **Large Number of Services:** As the number of microservices in your system grows, manually managing their configurations and dependencies becomes complex and error-prone. Self-registration automates this process.
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- **Need for Automatic Service** Discovery: When services need to find and communicate with each other without hardcoding network locations. This allows for greater flexibility and reduces coupling.
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- **Implementing Load Balancing:** Service registries like Eureka often integrate with load balancers, enabling them to automatically distribute traffic across available instances of a service that have registered themselves.
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- **Improving System Resilience:** If a service instance fails, the registry will eventually be updated (through heartbeats or health checks), and other services can discover and communicate with the remaining healthy instances.
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- **DevOps Automation:** This pattern aligns well with DevOps practices, allowing for more automated deployment and management of microservices.
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## Real-World Applications of Self-Registration pattern
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- E-Commerce platforms have numerous independent services for product catalogs, order processing, payments, shipping, etc. Self-registration allows these services to dynamically discover and communicate with each other as the system scales during peak loads or as new features are deployed.
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- Streaming services rely on many microservices for user authentication, content delivery networks (CDNs), recommendation engines, billing systems, etc. Self-registration helps these services adapt to varying user demands and infrastructure changes.
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- Social media These platforms use microservices for managing user profiles, timelines, messaging, advertising, and more. Self-registration enables these services to scale independently and handle the massive traffic they experience.
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## Advantages
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- Microservices can dynamically locate and communicate with each other without needing to know their specific network addresses beforehand. This is crucial in dynamic environments where IP addresses and ports can change frequently.
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- Reduces the need for manual configuration of service locations in each microservice. Services don't need to be updated every time another service's location changes.
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- Scaling microservices up or down becomes easier. New instances automatically register themselves with the service registry, making them immediately discoverable by other services without manual intervention.
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- If a service instance fails, it will eventually stop sending heartbeats to the registry and will be removed. Consumers can then discover and connect to other healthy instances, improving the system's overall resilience.
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- Services are less tightly coupled as they don't have direct dependencies on the physical locations of other services. This makes deployments and updates more flexible.
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- Service registries often integrate with load balancers. When a new service instance registers, the load balancer can automatically include it in the pool of available instances, distributing traffic effectively.
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- Microservices can be deployed across different environments (development, testing, production) without significant changes to their discovery mechanism, as long as they are configured to connect to the appropriate service registry for that environment.
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## Trade-offs
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- Introducing a service registry adds another component to your system that needs to be set up, managed, and monitored. This increases the overall complexity of the infrastructure.
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- The service registry itself becomes a critical component. If the service registry becomes unavailable, it can disrupt communication between microservices. High availability for the service registry is therefore essential.
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- Microservices need to communicate with the service registry for registration, sending heartbeats, and querying for other services. This can lead to increased network traffic.
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- There might be a slight delay between when a microservice instance starts and when it becomes fully registered and discoverable in the service registry. This needs to be considered, especially during scaling events.
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- You need to consider how your microservices will behave if they fail to register with the service registry upon startup. Robust error handling and retry mechanisms are often necessary.
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- Microservices need to include and configure client libraries (like the Eureka Discovery Client) to interact with the service registry. This adds a dependency to your application code.
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- In distributed service registries, ensuring consistency of the registry data across all nodes can be a challenge. Different registries might have different consistency models (e.g., eventual consistency).
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## References
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- Microservices Patterns: https://microservices.io/
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- Eureka Documentation: https://github.com/Netflix/eureka | https://spring.io/projects/spring-cloud-netflix
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- Spring Boot Documentation: https://spring.io/projects/spring-boot
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- Spring Cloud OpenFeignDocumentation: https://spring.io/projects/spring-cloud-openfeign
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- Spring Boot Actuator Documentation: https://www.baeldung.com/spring-boot-actuators
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/mvnw text eol=lf
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*.cmd text eol=crlf
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HELP.md
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target/
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!.mvn/wrapper/maven-wrapper.jar
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!**/src/main/**/target/
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!**/src/test/**/target/
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### STS ###
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.apt_generated
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.classpath
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.factorypath
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.project
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.settings
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.springBeans
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.sts4-cache
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### IntelliJ IDEA ###
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.idea
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*.iws
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*.iml
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*.ipr
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### NetBeans ###
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/nbproject/private/
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/nbbuild/
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/dist/
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/nbdist/
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/.nb-gradle/
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build/
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!**/src/main/**/build/
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!**/src/test/**/build/
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### VS Code ###
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.vscode/
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# Licensed to the Apache Software Foundation (ASF) under one
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# or more contributor license agreements. See the NOTICE file
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# distributed with this work for additional information
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# regarding copyright ownership. The ASF licenses this file
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# to you under the Apache License, Version 2.0 (the
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# "License"); you may not use this file except in compliance
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# with the License. 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,
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# software distributed under the License is distributed on an
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# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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# KIND, either express or implied. See the License for the
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# specific language governing permissions and limitations
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# under the License.
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wrapperVersion=3.3.2
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distributionType=only-script
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distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.9/apache-maven-3.9.9-bin.zip
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#!/bin/sh
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# ----------------------------------------------------------------------------
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# Licensed to the Apache Software Foundation (ASF) under one
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# or more contributor license agreements. See the NOTICE file
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# distributed with this work for additional information
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# regarding copyright ownership. The ASF licenses this file
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# to you under the Apache License, Version 2.0 (the
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# "License"); you may not use this file except in compliance
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# with the License. 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,
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# software distributed under the License is distributed on an
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# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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# KIND, either express or implied. See the License for the
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# specific language governing permissions and limitations
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# under the License.
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# ----------------------------------------------------------------------------
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# ----------------------------------------------------------------------------
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# Apache Maven Wrapper startup batch script, version 3.3.2
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#
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# Optional ENV vars
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# -----------------
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# JAVA_HOME - location of a JDK home dir, required when download maven via java source
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# MVNW_REPOURL - repo url base for downloading maven distribution
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# MVNW_USERNAME/MVNW_PASSWORD - user and password for downloading maven
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# MVNW_VERBOSE - true: enable verbose log; debug: trace the mvnw script; others: silence the output
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# ----------------------------------------------------------------------------
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set -euf
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[ "${MVNW_VERBOSE-}" != debug ] || set -x
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# OS specific support.
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native_path() { printf %s\\n "$1"; }
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case "$(uname)" in
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CYGWIN* | MINGW*)
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[ -z "${JAVA_HOME-}" ] || JAVA_HOME="$(cygpath --unix "$JAVA_HOME")"
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native_path() { cygpath --path --windows "$1"; }
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;;
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esac
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# set JAVACMD and JAVACCMD
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set_java_home() {
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# For Cygwin and MinGW, ensure paths are in Unix format before anything is touched
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if [ -n "${JAVA_HOME-}" ]; then
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if [ -x "$JAVA_HOME/jre/sh/java" ]; then
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# IBM's JDK on AIX uses strange locations for the executables
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JAVACMD="$JAVA_HOME/jre/sh/java"
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JAVACCMD="$JAVA_HOME/jre/sh/javac"
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else
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JAVACMD="$JAVA_HOME/bin/java"
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JAVACCMD="$JAVA_HOME/bin/javac"
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if [ ! -x "$JAVACMD" ] || [ ! -x "$JAVACCMD" ]; then
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echo "The JAVA_HOME environment variable is not defined correctly, so mvnw cannot run." >&2
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echo "JAVA_HOME is set to \"$JAVA_HOME\", but \"\$JAVA_HOME/bin/java\" or \"\$JAVA_HOME/bin/javac\" does not exist." >&2
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return 1
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fi
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fi
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else
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JAVACMD="$(
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'set' +e
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'unset' -f command 2>/dev/null
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'command' -v java
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)" || :
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JAVACCMD="$(
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'set' +e
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'unset' -f command 2>/dev/null
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'command' -v javac
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)" || :
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if [ ! -x "${JAVACMD-}" ] || [ ! -x "${JAVACCMD-}" ]; then
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echo "The java/javac command does not exist in PATH nor is JAVA_HOME set, so mvnw cannot run." >&2
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return 1
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fi
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fi
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}
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# hash string like Java String::hashCode
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hash_string() {
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str="${1:-}" h=0
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while [ -n "$str" ]; do
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char="${str%"${str#?}"}"
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h=$(((h * 31 + $(LC_CTYPE=C printf %d "'$char")) % 4294967296))
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str="${str#?}"
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done
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printf %x\\n $h
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}
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verbose() { :; }
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[ "${MVNW_VERBOSE-}" != true ] || verbose() { printf %s\\n "${1-}"; }
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die() {
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printf %s\\n "$1" >&2
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exit 1
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}
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trim() {
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# MWRAPPER-139:
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# Trims trailing and leading whitespace, carriage returns, tabs, and linefeeds.
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# Needed for removing poorly interpreted newline sequences when running in more
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# exotic environments such as mingw bash on Windows.
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printf "%s" "${1}" | tr -d '[:space:]'
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}
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# parse distributionUrl and optional distributionSha256Sum, requires .mvn/wrapper/maven-wrapper.properties
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while IFS="=" read -r key value; do
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case "${key-}" in
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distributionUrl) distributionUrl=$(trim "${value-}") ;;
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distributionSha256Sum) distributionSha256Sum=$(trim "${value-}") ;;
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esac
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done <"${0%/*}/.mvn/wrapper/maven-wrapper.properties"
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[ -n "${distributionUrl-}" ] || die "cannot read distributionUrl property in ${0%/*}/.mvn/wrapper/maven-wrapper.properties"
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case "${distributionUrl##*/}" in
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maven-mvnd-*bin.*)
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MVN_CMD=mvnd.sh _MVNW_REPO_PATTERN=/maven/mvnd/
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case "${PROCESSOR_ARCHITECTURE-}${PROCESSOR_ARCHITEW6432-}:$(uname -a)" in
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*AMD64:CYGWIN* | *AMD64:MINGW*) distributionPlatform=windows-amd64 ;;
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:Darwin*x86_64) distributionPlatform=darwin-amd64 ;;
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:Darwin*arm64) distributionPlatform=darwin-aarch64 ;;
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:Linux*x86_64*) distributionPlatform=linux-amd64 ;;
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*)
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echo "Cannot detect native platform for mvnd on $(uname)-$(uname -m), use pure java version" >&2
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distributionPlatform=linux-amd64
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;;
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esac
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distributionUrl="${distributionUrl%-bin.*}-$distributionPlatform.zip"
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;;
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maven-mvnd-*) MVN_CMD=mvnd.sh _MVNW_REPO_PATTERN=/maven/mvnd/ ;;
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*) MVN_CMD="mvn${0##*/mvnw}" _MVNW_REPO_PATTERN=/org/apache/maven/ ;;
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esac
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# apply MVNW_REPOURL and calculate MAVEN_HOME
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# maven home pattern: ~/.m2/wrapper/dists/{apache-maven-<version>,maven-mvnd-<version>-<platform>}/<hash>
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[ -z "${MVNW_REPOURL-}" ] || distributionUrl="$MVNW_REPOURL$_MVNW_REPO_PATTERN${distributionUrl#*"$_MVNW_REPO_PATTERN"}"
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distributionUrlName="${distributionUrl##*/}"
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distributionUrlNameMain="${distributionUrlName%.*}"
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distributionUrlNameMain="${distributionUrlNameMain%-bin}"
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MAVEN_USER_HOME="${MAVEN_USER_HOME:-${HOME}/.m2}"
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MAVEN_HOME="${MAVEN_USER_HOME}/wrapper/dists/${distributionUrlNameMain-}/$(hash_string "$distributionUrl")"
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exec_maven() {
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unset MVNW_VERBOSE MVNW_USERNAME MVNW_PASSWORD MVNW_REPOURL || :
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exec "$MAVEN_HOME/bin/$MVN_CMD" "$@" || die "cannot exec $MAVEN_HOME/bin/$MVN_CMD"
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}
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if [ -d "$MAVEN_HOME" ]; then
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verbose "found existing MAVEN_HOME at $MAVEN_HOME"
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exec_maven "$@"
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fi
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case "${distributionUrl-}" in
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*?-bin.zip | *?maven-mvnd-?*-?*.zip) ;;
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*) die "distributionUrl is not valid, must match *-bin.zip or maven-mvnd-*.zip, but found '${distributionUrl-}'" ;;
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esac
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# prepare tmp dir
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if TMP_DOWNLOAD_DIR="$(mktemp -d)" && [ -d "$TMP_DOWNLOAD_DIR" ]; then
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clean() { rm -rf -- "$TMP_DOWNLOAD_DIR"; }
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trap clean HUP INT TERM EXIT
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else
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die "cannot create temp dir"
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fi
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mkdir -p -- "${MAVEN_HOME%/*}"
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# Download and Install Apache Maven
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verbose "Couldn't find MAVEN_HOME, downloading and installing it ..."
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verbose "Downloading from: $distributionUrl"
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verbose "Downloading to: $TMP_DOWNLOAD_DIR/$distributionUrlName"
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# select .zip or .tar.gz
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if ! command -v unzip >/dev/null; then
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distributionUrl="${distributionUrl%.zip}.tar.gz"
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distributionUrlName="${distributionUrl##*/}"
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fi
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# verbose opt
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__MVNW_QUIET_WGET=--quiet __MVNW_QUIET_CURL=--silent __MVNW_QUIET_UNZIP=-q __MVNW_QUIET_TAR=''
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[ "${MVNW_VERBOSE-}" != true ] || __MVNW_QUIET_WGET='' __MVNW_QUIET_CURL='' __MVNW_QUIET_UNZIP='' __MVNW_QUIET_TAR=v
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# normalize http auth
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case "${MVNW_PASSWORD:+has-password}" in
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'') MVNW_USERNAME='' MVNW_PASSWORD='' ;;
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has-password) [ -n "${MVNW_USERNAME-}" ] || MVNW_USERNAME='' MVNW_PASSWORD='' ;;
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esac
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if [ -z "${MVNW_USERNAME-}" ] && command -v wget >/dev/null; then
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verbose "Found wget ... using wget"
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wget ${__MVNW_QUIET_WGET:+"$__MVNW_QUIET_WGET"} "$distributionUrl" -O "$TMP_DOWNLOAD_DIR/$distributionUrlName" || die "wget: Failed to fetch $distributionUrl"
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elif [ -z "${MVNW_USERNAME-}" ] && command -v curl >/dev/null; then
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verbose "Found curl ... using curl"
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curl ${__MVNW_QUIET_CURL:+"$__MVNW_QUIET_CURL"} -f -L -o "$TMP_DOWNLOAD_DIR/$distributionUrlName" "$distributionUrl" || die "curl: Failed to fetch $distributionUrl"
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elif set_java_home; then
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verbose "Falling back to use Java to download"
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javaSource="$TMP_DOWNLOAD_DIR/Downloader.java"
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targetZip="$TMP_DOWNLOAD_DIR/$distributionUrlName"
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cat >"$javaSource" <<-END
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public class Downloader extends java.net.Authenticator
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{
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protected java.net.PasswordAuthentication getPasswordAuthentication()
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{
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return new java.net.PasswordAuthentication( System.getenv( "MVNW_USERNAME" ), System.getenv( "MVNW_PASSWORD" ).toCharArray() );
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}
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public static void main( String[] args ) throws Exception
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{
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setDefault( new Downloader() );
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java.nio.file.Files.copy( java.net.URI.create( args[0] ).toURL().openStream(), java.nio.file.Paths.get( args[1] ).toAbsolutePath().normalize() );
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}
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}
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END
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# For Cygwin/MinGW, switch paths to Windows format before running javac and java
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verbose " - Compiling Downloader.java ..."
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"$(native_path "$JAVACCMD")" "$(native_path "$javaSource")" || die "Failed to compile Downloader.java"
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verbose " - Running Downloader.java ..."
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"$(native_path "$JAVACMD")" -cp "$(native_path "$TMP_DOWNLOAD_DIR")" Downloader "$distributionUrl" "$(native_path "$targetZip")"
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fi
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# If specified, validate the SHA-256 sum of the Maven distribution zip file
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if [ -n "${distributionSha256Sum-}" ]; then
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distributionSha256Result=false
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if [ "$MVN_CMD" = mvnd.sh ]; then
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echo "Checksum validation is not supported for maven-mvnd." >&2
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echo "Please disable validation by removing 'distributionSha256Sum' from your maven-wrapper.properties." >&2
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exit 1
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elif command -v sha256sum >/dev/null; then
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if echo "$distributionSha256Sum $TMP_DOWNLOAD_DIR/$distributionUrlName" | sha256sum -c >/dev/null 2>&1; then
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distributionSha256Result=true
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fi
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elif command -v shasum >/dev/null; then
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if echo "$distributionSha256Sum $TMP_DOWNLOAD_DIR/$distributionUrlName" | shasum -a 256 -c >/dev/null 2>&1; then
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distributionSha256Result=true
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fi
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else
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echo "Checksum validation was requested but neither 'sha256sum' or 'shasum' are available." >&2
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echo "Please install either command, or disable validation by removing 'distributionSha256Sum' from your maven-wrapper.properties." >&2
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exit 1
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fi
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if [ $distributionSha256Result = false ]; then
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echo "Error: Failed to validate Maven distribution SHA-256, your Maven distribution might be compromised." >&2
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echo "If you updated your Maven version, you need to update the specified distributionSha256Sum property." >&2
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exit 1
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fi
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fi
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# unzip and move
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if command -v unzip >/dev/null; then
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unzip ${__MVNW_QUIET_UNZIP:+"$__MVNW_QUIET_UNZIP"} "$TMP_DOWNLOAD_DIR/$distributionUrlName" -d "$TMP_DOWNLOAD_DIR" || die "failed to unzip"
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else
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tar xzf${__MVNW_QUIET_TAR:+"$__MVNW_QUIET_TAR"} "$TMP_DOWNLOAD_DIR/$distributionUrlName" -C "$TMP_DOWNLOAD_DIR" || die "failed to untar"
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fi
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printf %s\\n "$distributionUrl" >"$TMP_DOWNLOAD_DIR/$distributionUrlNameMain/mvnw.url"
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mv -- "$TMP_DOWNLOAD_DIR/$distributionUrlNameMain" "$MAVEN_HOME" || [ -d "$MAVEN_HOME" ] || die "fail to move MAVEN_HOME"
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clean || :
259+
exec_maven "$@"

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