带有非嵌入式Tomcat的Spring引导:加载程序违反约束错误

Question

尝试使用Spring显示JSP时出错。这是我的配置：

• Spring源STS (最后版本)
• Spring 1.1.8 (最近一次发布)
• Java 1.7
• Tomcat 8.0.14 (我不使用嵌入式tomcat，所以我在添加spring引导应用程序时手动启动)

我的JSP文件是基本文件：

TEST

这是我的pom.xml：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>

<groupId>com.edhec</groupId>
<artifactId>stdapps</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>

<name>stdapps</name>
<description>Project stdapps</description>

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.1.8.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-security</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-rest</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-websocket</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-tomcat</artifactId>
        <scope>provided</scope>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-c3p0</artifactId>
        <version>4.3.6.Final</version>
    </dependency>
    <dependency>
        <groupId>com.oracle</groupId>
        <artifactId>ojdbc14</artifactId>
        <version>10.2.0.4.0</version>
    </dependency>
    <!-- CAS Client -->
    <dependency>
       <groupId>org.jasig.cas.client</groupId>
       <artifactId>cas-client-core</artifactId>
       <version>3.3.3</version>
       <scope>runtime</scope>
       <type>jar</type>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-cas</artifactId>
        <type>jar</type>
        <scope>compile</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-taglibs</artifactId>
    </dependency>
    <dependency>
        <groupId>commons-beanutils</groupId>
        <artifactId>commons-beanutils</artifactId>
        <version>1.9.2</version>
    </dependency>
    <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-lang3</artifactId>
        <version>3.3.2</version>
    </dependency>

</dependencies>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <start-class>com.edhec.stdapps.Application</start-class>
    <java.version>1.7</java.version>
    <tomcat.version>8.0.14</tomcat.version>
</properties>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

​

下面是我遇到的错误：

java.lang.LinkageError: loader constraint violation: when resolving method "org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(Ljavax/servlet/ServletConfig;)Lorg/apache/tomcat/InstanceManager;" the class loader (instance of org/apache/jasper/servlet/JasperLoader) of the current class, org/apache/jsp/WEB_002dINF/views/agreement2/index_jsp, and the class loader (instance of java/net/URLClassLoader) for resolved class, org/apache/jasper/runtime/InstanceManagerFactory, have different Class objects for the type .getInstanceManager(Ljavax/servlet/ServletConfig;)Lorg/apache/tomcat/InstanceManager; used in the signature

我认为它与el或jsp-api版本有关系，我尝试在pom.xml中手动添加，但得到了相同的错误，有时也有'noClassDefFoundError在我编译的jsp‘。

有人看到出什么问题了吗？

Answer 1

由于您对spring-boot-starter-web和spring-boot-starter-websocket的依赖以及它们的传递依赖，所以您将Tomcat打包到war文件中。这将导致Tomcat类的两个不同版本可用，并导致约束冲突。您需要将Tomcat依赖项标记为提供的，这样它们就不会在WEB-INF/lib中打包。

将下列依赖项添加到pom中：

<dependency> 
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-tomcat</artifactId>
    <scope>provided</scope>
</dependency>
<dependency>
    <groupId>org.apache.tomcat.embed</groupId>
    <artifactId>tomcat-embed-websocket</artifactId>
    <scope>provided</scope>
</dependency>

最好将依赖项标记为提供的，而不是完全排除它们，因为它允许将war文件部署到Tomcat或使用java -jar执行。这是因为所提供的依赖项打包在WEB-INF/lib-provided中，它们将被独立的Servlet容器忽略，但在使用嵌入式容器时是可用的。

Answer 2

在gradle中，我将这一行添加到依赖项中：

dependencies {
   ...
   providedRuntime('org.springframework.boot:spring-boot-starter-tomcat')
   ...
}