如何将JFreeChart库添加到JDK?错误:软件包org.jfree.chart不存在 [英] How to add JFreeChart library to JDK? Error: package org.jfree.chart does not exist

问题描述

经过使用其他语言的一些经验之后，我开始使用Java.对于所有这些人，我一直在使用Atom代码编辑器.因此，我使用Java进行了管理，但是最近我发现我需要使用外部库JFreeChart.

I'm starting with Java after some experience with other languages. For all of them I have been using Atom code editor. And so I have managed with Java but recently I have found out that I need to use an external library JFreeChart.

我正在使用JDK 8在cmd(Windows)上运行Java，并且没有使用任何IDE.

I am using JDK 8 to run Java on cmd (Windows) and I'm not using any IDE.

我到目前为止已经尝试过:

I tried so far:

javac -cp "lib/*" ./Test.java

在 lib 文件夹中具有 jfreechart-1.0.19.jar 和 jcommon-1.0.23.jar .

将Maven与pom.xml一起使用:

Using Maven with 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>org.codehaus.mojo</groupId>
    <artifactId>my-project</artifactId>
    <version>1.0</version>

    <!-- https://mvnrepository.com/artifact/org.jfree/jfreechart -->
    <dependencies>
      <dependency>
        <groupId>org.jfree</groupId>
        <artifactId>jfreechart</artifactId>
        <version>1.5.0</version>
    </dependency>
    <dependency>
      <groupId>org.jfree</groupId>
      <artifactId>jcommon</artifactId>
      <version>1.0.24</version>
    </dependency>
  </dependencies>
</project>

使用CLASSPATH系统变量:

Using CLASSPATH system variable:

D:\Study\Java\code\com\lib\jfreechart-1.0.19.jar
D:\Study\Java\code\com\lib\jcommon-1.0.23.jar

将jar文件放入 D:\ Program Files \ Java \ jdk \ jre \ lib \ ext

到目前为止，我总是得到:

and so far I always get:

error: package org.jfree.chart does not exist

我现在有点发疯了，所以我要寻求帮助.我该怎么做才能正确添加该库?

I'm kinda going nuts now so I'm asking for help. What can I do to add this library correctly ?

这是我的代码(也许我导入不正确):

Here is my code (maybe I'm importing incorrectly):

import org.jfree.chart.JFreeChart;
import org.jfree.chart.ChartUtilities;
import org.jfree.chart.ChartFactory;
import org.jfree.data.general.DefaultPieDataset;
import java.io.File;

public class Test {
  public static void main(String[] args) {
    DefaultPieDataset pieDataset = new DefaultPieDataset();
  }
}

完整的错误消息(在所有情况下都是相同的):

Full error message (in all cases it was the same):

D:\Study\Java\code\jfc> javac .\Test.java
Picked up JAVA_TOOL_OPTIONS: -Dfile.encoding=UTF8
.\Test.java:2: error: package org.jfree.chart does not exist
import org.jfree.chart.JFreeChart;

                      ^
.\Test.java:3: error: package org.jfree.chart does not exist
import org.jfree.chart.ChartUtilities;
                      ^
.\Test.java:4: error: package org.jfree.chart does not exist
import org.jfree.chart.ChartFactory;
                      ^
.\Test.java:5: error: package org.jfree.data.general does not exist
import org.jfree.data.general.DefaultPieDataset;
                             ^
.\Test.java:10: error: cannot find symbol
    DefaultPieDataset pieDataset = new DefaultPieDataset();
    ^
  symbol:   class DefaultPieDataset
  location: class Test
.\Test.java:10: error: cannot find symbol
    DefaultPieDataset pieDataset = new DefaultPieDataset();
                                       ^
  symbol:   class DefaultPieDataset
  location: class Test
6 errors

推荐答案

由于使用的是pom.xml，因此您已经破坏"了项目，因此需要使用Maven进行构建.

Since you are using a pom.xml you've "mavenized" your project and hence you need to use Maven to build it.

所以有几件事:

1. 确保已正确下载，安装和设置Maven(它必须是路径的路径)...(如果尚未这样做的话)请检出 http://repo1. maven.org/maven2 )，并指定您本地的Maven存储库(它将库下载到的地方).
2. 确保已根据标准项目结构对代码进行了结构化.

1. Be sure you have downloaded, installed and setup Maven correctly (it needs to be path of your path) ... if you've not already done so check out Welcome to Apache Maven
2. Make sure your settings.xml is configured correctly to point to a Maven repository (i.e. http://repo1.maven.org/maven2) as well as specify your local Maven repository (where it'll download the lib's to).
3. Ensure you have structured your code according to the standard project structure.

这意味着您的Test类将需要放置在包org.codehaus.mojo中.因此，根据标准项目结构，Test将出现在目录结构D:\Study\Java\code\jfc\src\main\java\org\codehaus\mojo\Test.java

This would mean that your Test class would need to placed in the package org.codehaus.mojo. So according to the standard project structure, Test would appear in the directory structure D:\Study\Java\code\jfc\src\main\java\org\codehaus\mojo\Test.java

1. 您pom.xml应该坐在D:\Study\Java\code\jfc\
2. 在与./pom.xml相同的目录中，运行mvn package命令.
3. 如果一切设置正确，Maven将连接到您已配置的远程存储库，将这些软件包下载到本地存储库并构建一个JAR文件，然后您可以运行该文件.

1. You pom.xml should sit in D:\Study\Java\code\jfc\
2. In the same directory as your ./pom.xml run the mvn package command.
3. If everything is setup correctly, Maven will connect to the remote repository you've configured, download those packages to your local repository and build a JAR file, which you can then run.

已通读五分钟之内的Maven

更新:包装具有依赖项的jar.

UPDATE: Packaging a jar with dependencies.

为了打包具有相关性的jar，您需要将maven-assembly-plugin添加到您的pom.xml中.将其添加到pom.xml并运行mvn package后，它会生成(根据您的示例)名为my-project-1.0-jar-with-dependencies.jar的jar(您可以将descriptorRef更改为更好的名称，也可以排除它) .此jar应该包含项目需要的所有运行时依赖项.

In order to package a jar with dependencies, you will need to add the maven-assembly-plugin to your pom.xml. Once you've added this to your pom.xml and run mvn package it should generate (according to your example) a jar called my-project-1.0-jar-with-dependencies.jar (you can change the descriptorRef for a better name, or exclude it). This jar should contain all the run-time dependencies your project needs.

<build>
  <plugins>
    <plugin>
      <artifactId>maven-assembly-plugin</artifactId>
      <configuration>
        <archive>
          <manifest>
            <mainClass>org.codehaus.mojo.Test</mainClass>
           </manifest>
        </archive>
        <descriptorRefs>
          <descriptorRef>jar-with-dependencies</descriptorRef>
        </descriptorRefs>
      </configuration>
      <executions>
        <execution>
          <id>make-assembly</id> <!-- this is used for inheritance merges -->
          <phase>package</phase> <!-- bind to the packaging phase -->
          <goals>
            <goal>single</goal>
          </goals>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>

已通读 Maven程序插件:用法

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