Question

我是Maven的新手，我正在尝试编写一小段Java代码。我包括一些包裹。 Maven似乎下载了我预期需要的所有内容，但是当涉及编译时，它无法说它找不到特定的类。错误进一步表明它无法找到我的任何导入。有人能告诉我我错过了什么吗？

这是我的代码：

package in.myscratchpad.app;

import com.amazonaws.AmazonClientException;
import com.amazonaws.AmazonServiceException;
import com.amazonaws.auth.AWSCredentials;
import com.amazonaws.auth.profile.ProfileCredentialsProvider;
import com.amazonaws.regions.Region;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.dynamodb.AmazonDynamoDBClient;

/**
 * Hello world!
 *
 */
public class App
{
    public static void main( String[] args )
    {
        System.out.println( "Hello World!" );
        AmazonDynamoDBClientBuilder builder = AmazonDBClientBuilder.standard();
    }
}

这是我的pom.xml：

<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>in.myscratchpad.app</groupId>
  <artifactId>my-app</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>my-app</name>
  <url>http://maven.apache.org</url>
 <build>
  <plugins>
  <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-jar-plugin</artifactId>
    <version>2.4</version>
    <configuration>
      <archive>
        <manifest>
          <mainClass>in.myscratchpad.app.App</mainClass>
        </manifest>
      </archive>
    </configuration>
  </plugin>
  </plugins>
 </build>
  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>com.amazonaws</groupId>
      <artifactId>aws-java-sdk</artifactId>
      <version>1.11.60</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>
</project>

这些是我得到的错误：

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project my-app: Compilation failure: Compilation failure:
[ERROR] /home/ec2-user/projects/kinesisProducer1/my-app/src/main/java/in/myscratchpad/app/App.java:[3,21] package com.amazonaws does not exist
[ERROR] /home/ec2-user/projects/kinesisProducer1/my-app/src/main/java/in/myscratchpad/app/App.java:[4,21] package com.amazonaws does not exist
[ERROR] /home/ec2-user/projects/kinesisProducer1/my-app/src/main/java/in/myscratchpad/app/App.java:[5,26] package com.amazonaws.auth does not exist
[ERROR] /home/ec2-user/projects/kinesisProducer1/my-app/src/main/java/in/myscratchpad/app/App.java:[6,34] package com.amazonaws.auth.profile does not exist
[ERROR] /home/ec2-user/projects/kinesisProducer1/my-app/src/main/java/in/myscratchpad/app/App.java:[7,29] package com.amazonaws.regions does not exist
[ERROR] /home/ec2-user/projects/kinesisProducer1/my-app/src/main/java/in/myscratchpad/app/App.java:[8,29] package com.amazonaws.regions does not exist
[ERROR] /home/ec2-user/projects/kinesisProducer1/my-app/src/main/java/in/myscratchpad/app/App.java:[9,39] package com.amazonaws.services.dynamodb does not exist
[ERROR] /home/ec2-user/projects/kinesisProducer1/my-app/src/main/java/in/myscratchpad/app/App.java:[20,9] cannot find symbol
[ERROR] symbol:   class AmazonDynamoDBClientBuilder
[ERROR] location: class in.myscratchpad.app.App
[ERROR] /home/ec2-user/projects/kinesisProducer1/my-app/src/main/java/in/myscratchpad/app/App.java:[20,47] cannot find symbol
[ERROR] symbol:   variable AmazonDBClientBuilder
[ERROR] location: class in.myscratchpad.app.App
[ERROR] -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException

当我简单地保留没有AWS包的Hello，World代码时，它工作正常，当我尝试构建服务客户端时，我得到了这些错误。

Answer 1

它说

...cannot find symbol
[ERROR] symbol:   variable AmazonDBClientBuilder
[ERROR] location: class in.myscratchpad.app.App

哪些接缝可以清楚地解释它可以编译in.myscratchpad.app.App，因为它中有一个符号（即AmazonDBClientBuilder）无法找到！

我不知道这个课程是针对什么的，但鉴于此

您没有导入AmazonDBClientBuilder类
您将结果分配到AmazonDynamoDBClientBuilder类型

不是代码中的拼写错误，您应该使用AmazonDynamoDBClientBuilder.standard()代替吗？

下载依赖项后Maven无法找到类

1 个答案: