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远程仓库中有jar，但是编译时找不到：
artifacts could not be resolved...
...was cached in the local repository
详细错误信息：
Failed to execute goal on project amps-dcm:
Could not resolve dependencies for project com.zollty.pss:amps-dcm:war:0.0.1-SNAPSHOT:
The following artifacts could not be resolved: org.zollty.util:zollty-util:jar:1.0, org.zollty.log:zollty-log:jar:1.0:
Failure to find org.zollty.util:zollty-util:jar:1.0 in http://172.27.18.106:8081/nexus/content/groups/public
was cached in the local repository,
resolution will not be reattempted until the update interval of LocalMirrorId has elapsed or updates are forced -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR]
解决方案：
打开本地仓库目录，找到那个jar的位置，把残留的文件夹全都删除。然后再重新下载这个jar。
还是不行？有可能是parent项目中也存在xxx.lastUpdate的文件。所以把parent项目也清理一下。
例如：
<parent>
<groupId>org.zollty</groupId>
<artifactId>zollty-org</artifactId>
<version>1.0</version>
</parent>
那么，请检查
D:\C\Java\maven3\repo\org\zollty\zollty-org\1.0 目录！！
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transitive dependencies (if any) will not be available, enable debug logging for more details
详细错误如下：
[WARNING] The POM for org.zollty.util:zollty-util:jar:1.0 is invalid, transitive dependencies (if any) will not be available, enable debug logging for more details
解决方法： 显式引入:zollty-util:jar:1.0依赖的jar即可。
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maven 无法确定 <T>T 的类型参数;对于上限为 long,java.lang.Object 的类型变量 T
无法确定 <X>X 的类型参数；对于上限为 X,java.lang.Object 的类型变量 X，不存在唯一最大实例
原因是，默认编译器（javac）的问题。
解决方案：使用其他编译器，比如eclipse所用的编译器（JDT compiler from eclipse）。
在pom.xml中配置如下：
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>${java-version}</source>
<target>${java-version}</target>
<compilerId>eclipse</compilerId>
</configuration>
<dependencies>
<dependency>
<groupId>org.codehaus.plexus</groupId>
<artifactId>plexus-compiler-eclipse</artifactId>
<version>2.3</version>
</dependency>
</dependencies>
</plugin>参见：
http://www.eclipse.org/forums/index.php/t/1229/
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使用JDT compiler时出现 枚举类型switch报错 问题：
Cannot switch on a value of type. Only convertible int values or enum variables are permitted
例如：
class Foo {
static enum MyEnum { A }
void foo() { switch ( MyEnum.A ) { case A: } }
}分析和解决方法：
Turns out that the setting org.eclipse.jdt.core.compiler.compliance needs to be set to the target version in order for it to be able to recognize java.lang.Enum.
This setting is only set by plexus-compiler-eclipse when both targetVersion AND optimize is set. [1]
Modify your pom like this and it should work:
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version> <!-- or 3.0 -->
<configuration>
<compilerId>eclipse</compilerId>
<source>1.6</source>
<target>1.6</target>
<optimize>true</optimize> <!-- add this line! -->
I'm not sure why it was decided in plexus-compiler-eclipse that optimization would affect the compliance level, so this is in fact a workaround.
参见：https://github.com/sonatype/plexus-compiler/blob/master/plexus-compilers/plexus-compiler-eclipse/src/main/java/org/codehaus/plexus/compiler/eclipse/EclipseJavaCompiler.java#L156
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Maven报错：'version' contains an expression but should be a constant.
是因为 父pom还没有发布到仓库中，建议在仓库中检查一下父pom是否正确。
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报错：No compiler is provided in this environment. Perhaps you are running on a JRE rather than a JDK?
原因：JRE环境指定的是JRE目录，而不是JDK目录。
解决方法：
● Click on Windows -> Preferences -> Java -> Installed JREs -> Add -> Standard VM and Select JAVA_HOME.
● Select New JRE from Installed JREs and Press OK
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maven运行命令mvn mybatis-generator:generate 提示找不到数据库驱动问题
错误信息如下：
mybatis-generator classNotFoundException: com.mysql.jdbc.Driver
Caused by: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:50)
at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:244)
把驱动文件放在这个文件夹里 \Java\jdk1.6.0_02\jre\lib\ext
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Maven WTP无法引用工程中的项目模块(org.eclipse.wst.common.component)
也就是说，在org.eclipse.wst.common.component文件中缺少如下的语句：
<dependent-module archiveName="tre-client-2.0.2-SNAPSHOT.jar" deploy-path="/WEB-INF/lib"
handle="module:/resource/tre-client/tre-client">
<dependency-type>uses</dependency-type>
</dependent-module>
那是因为 被引用的项目的pom配置有问题，经我检查，问题出在如下一行
<resources>
<resource>
<directory>${basedir}/src/main/resources</directory>
</resource>
<resource>
<directory>${basedir}/src/main/java/com/zollty/report/client</directory>
<includes>
<include>*.xsd</include>
</includes>
<targetPath>${project.build.directory}/classes/com/zollty/report/client</targetPath>
</resource>
</resources> 但是，在这个目录下面，找不到任何 .xsd 文件，运行maven指令的时候不会报错，但是在这个WTP中就检测到了这个问题，所以没有生成这个引用。
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eclipse如何将Maven依赖的jar发布到tomcat的WEB-INF/lib下面
使用到m2e这个eclipse插件。
在.classpath文件中设置：
<classpathentry kind="con" path="org.eclipse.m2e.MAVEN2_CLASSPATH_CONTAINER">
<attributes>
<attribute name="maven.pomderived" value="true"/>
<attribute name="org.eclipse.jst.component.dependency" value="/WEB-INF/lib"/>
</attributes>
</classpathentry>
注意，有些插件是：
<classpathentry kind="con" path="org.maven.ide.eclipse.MAVEN2_CLASSPATH_CONTAINER">
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配置了拷贝(overlays)引入的war包的Eclipse-Maven 项目，当发布到服务器上时，没有拷贝到war中的文件到发布的服务器上。
<overlays> 的pom配置如下：
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.1.1</version>
<configuration>
<attachClasses>true</attachClasses>
<overlays>
<overlay>
<groupId>com.zollty.pss</groupId>
<artifactId>abframe</artifactId>
</overlay>
<overlay>
<!-- don't remove this tag. empty groupId/artifactId represents the current build -->
</overlay>
</overlays>
</configuration>
</plugin>
原因： 没有配置支持overlays的Eclipse插件，即m2e-wtp插件。
查看.project和.classpath文件：
有些Eclipse插件是这样
.project文件
<natures>
...
<nature>org.maven.ide.eclipse.maven2Nature</nature>
...
</natrues>
.classpath 文件
<classpathentry kind="con" path="org.maven.ide.eclipse.MAVEN2_CLASSPATH_CONTAINER">
<attributes>
<attribute name="maven.pomderived" value="true"/>
<attribute name="org.eclipse.jst.component.dependency" value="/WEB-INF/lib"/>
</attributes>
</classpathentry>
但是有些Eclipse插件是这样
.project文件
<natures>
...
<nature>org.eclipse.m2e.core.maven2Nature</nature>
...
</natures>
.classpath 文件
<classpathentry kind="con" path="org.eclipse.m2e.MAVEN2_CLASSPATH_CONTAINER">
<attributes>
<attribute name="maven.pomderived" value="true"/>
<attribute name="org.eclipse.jst.component.dependency" value="/WEB-INF/lib"/>
</attributes>
</classpathentry>
经测试，上面第二个配置可以正确使用maven的war包依赖自动发布的功能。
如果是第一个配置，那需要安装m2e-wtp插件。
安装后，完整的配置如下：
.project文件
<?xml version="1.0" encoding="UTF-8"?>
<projectDescription>
<name>amps-dcm</name>
<comment></comment>
<projects>
</projects>
<buildSpec>
<buildCommand>
<name>org.eclipse.wst.jsdt.core.javascriptValidator</name>
<arguments>
</arguments>
</buildCommand>
<buildCommand>
<name>org.eclipse.wst.common.project.facet.core.builder</name>
<arguments>
</arguments>
</buildCommand>
<buildCommand>
<name>com.genuitec.eclipse.j2eedt.core.WebClasspathBuilder</name>
<arguments>
</arguments>
</buildCommand>
<buildCommand>
<name>org.eclipse.jdt.core.javabuilder</name>
<arguments>
</arguments>
</buildCommand>
<buildCommand>
<name>com.genuitec.eclipse.j2eedt.core.J2EEProjectValidator</name>
<arguments>
</arguments>
</buildCommand>
<buildCommand>
<name>com.genuitec.eclipse.j2eedt.core.DeploymentDescriptorValidator</name>
<arguments>
</arguments>
</buildCommand>
<buildCommand>
<name>org.eclipse.wst.validation.validationbuilder</name>
<arguments>
</arguments>
</buildCommand>
<buildCommand>
<name>com.genuitec.eclipse.ast.deploy.core.DeploymentBuilder</name>
<arguments>
</arguments>
</buildCommand>
<buildCommand>
<name>org.eclipse.m2e.core.maven2Builder</name>
<arguments>
</arguments>
</buildCommand>
</buildSpec>
<natures>
<nature>org.eclipse.m2e.core.maven2Nature</nature>
<nature>org.eclipse.jem.workbench.JavaEMFNature</nature>
<nature>org.eclipse.wst.common.modulecore.ModuleCoreNature</nature>
<nature>com.genuitec.eclipse.ast.deploy.core.deploymentnature</nature>
<nature>com.genuitec.eclipse.j2eedt.core.webnature</nature>
<nature>org.eclipse.jdt.core.javanature</nature>
<nature>org.eclipse.wst.common.project.facet.core.nature</nature>
<nature>org.eclipse.wst.jsdt.core.jsNature</nature>
</natures>
</projectDescription>
.classpath 文件
<?xml version="1.0" encoding="UTF-8"?>
<classpath>
<classpathentry kind="src" output="target/classes" path="src/main/java">
<attributes>
<attribute name="optional" value="true"/>
<attribute name="maven.pomderived" value="true"/>
</attributes>
</classpathentry>
<classpathentry excluding="**" kind="src" output="target/classes" path="src/main/resources">
<attributes>
<attribute name="maven.pomderived" value="true"/>
</attributes>
</classpathentry>
<classpathentry kind="src" output="target/test-classes" path="src/test/java">
<attributes>
<attribute name="optional" value="true"/>
<attribute name="maven.pomderived" value="true"/>
</attributes>
</classpathentry>
<classpathentry excluding="**" kind="src" output="target/test-classes" path="src/test/resources">
<attributes>
<attribute name="maven.pomderived" value="true"/>
</attributes>
</classpathentry>
<classpathentry
kind="con"
path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.6">
<attributes>
<attribute name="maven.pomderived" value="true"/>
</attributes>
</classpathentry>
<classpathentry kind="con" path="org.eclipse.m2e.MAVEN2_CLASSPATH_CONTAINER">
<attributes>
<attribute name="maven.pomderived" value="true"/>
<attribute name="org.eclipse.jst.component.dependency" value="/WEB-INF/lib"/>
</attributes>
</classpathentry>
<classpathentry kind="output" path="target/classes"/>
</classpath>