文档章节

java命令行下如何设置classpath类路径

猪刚烈
 猪刚烈
发布于 2014/10/12 11:40
字数 867
阅读 13
收藏 0

以往基于构建工具和IDE工作,很少使用命令行执行程序,但偶尔使用命令行的时候关于类路径的设置都要查阅一下说明文档,这里找到一个详尽清晰的说明,以备自查.特别指明的是:classpath最好使用""(window系统下)或''(linux系统下)括起来,否则可能会因为包含的jar路径上含有空格一类的特殊字符导致出现奇怪的错误提示.,本文转自wikipedia,地址: http://en.wikipedia.org/wiki/Classpath_%28Java%29

Setting the path to execute Java programs

Basic usage

Suppose we have a package called org.mypackage containing the classes:

  • HelloWorld (main class)
  • SupportClass
  • UtilClass

and the files defining this package are stored physically under the directory D:\myprogram (on Windows) or /home/user/myprogram (on Linux).

The file structure will look like this:

Microsoft Windows Linux
D:\myprogram\
      |
      ---> org\  
            |
            ---> mypackage\
                     |
                     ---> HelloWorld.class       
                     ---> SupportClass.class   
                     ---> UtilClass.class
/home/user/myprogram/
            |
            ---> org/  
                  |
                  ---> mypackage/
                           |
                           ---> HelloWorld.class       
                           ---> SupportClass.class   
                           ---> UtilClass.class

When we invoke Java, we specify the name of the application to run: org.mypackage.HelloWorld. However we must also tell Java where to look for the files and directories defining our package. So to launch the program, we use the following command:

Microsoft Windows Linux
java -classpath D:\myprogram org.mypackage.HelloWorld
java -classpath /home/user/myprogram org.mypackage.HelloWorld

where:

  • -classpath D:\myprogram sets the path to the packages used in the program (on Linux, -classpath /home/user/myprogram)
  • org.mypackage.HelloWorld is the name of the main class

Note that if we ran Java in D:\myprogram\ (on Linux, /home/user/myprogram/) then we would not need to specify the classpath since Java implicitly looks in the current working directory for files containing classes.

Adding all JAR files in a directory

In Java 6 and higher, one can add all jar-files in a specific directory to the classpath using wildcard notation.

Windows example:

java -classpath ".;c:\mylib\*" MyApp

Linux example:

java -classpath '.:/mylib/*' MyApp

Setting the path through an environment variable

The environment variable named CLASSPATH may be alternatively used to set the classpath. For the above example, we could also use on Windows:

Sometimes you have to check the JAVA_HOME also, if it is pointing towards the right JDK version

set CLASSPATH=D:\myprogram
java org.mypackage.HelloWorld

Setting the path of a Jar file

Now, suppose the program uses a supporting library enclosed in a Jar file called supportLib.jar, physically in the directory D:\myprogram\lib\.

The corresponding physical file structure is :

D:\myprogram\
      |
      ---> lib\
            |
            ---> supportLib.jar
      |
      ---> org\
            |
            --> mypackage\
                       |
                       ---> HelloWorld.class
                       ---> SupportClass.class
                       ---> UtilClass.class

We should use the following command-line option:

java -classpath D:\myprogram;D:\myprogram\lib\supportLib.jar org.mypackage.HelloWorld

or alternatively:

set CLASSPATH=D:\myprogram;D:\myprogram\lib\supportLib.jar
java org.mypackage.HelloWorld

Setting the path in a Manifest file

Suppose that our program has been enclosed in a Jar file called helloWorld.jar, put directly in the D:\myprogram directory. We have the following file structure:

D:\myprogram\
      |
      ---> helloWorld.jar 
      |
      ---> lib\  
            |
            ---> supportLib.jar

The manifest file defined in this Jar file has this definition:

Main-Class: org.mypackage.HelloWorld
Class-Path: lib/supportLib.jar

Note: It's important that the manifest file ends with either a new line or carriage return.

Also, note that the classpath string in this case describes the location of the supportLib.jar file relative to the location of the helloWorld.jar file, and not as an absolute file path (as it might be when setting the -classpath parameter on the command line, for example). Thus, the actual locations of the jar file and its support library are irrelevant so long as the relative directory structure between the two is preserved.

To launch the program, we can use the following command:

java -jar D:\myprogram\helloWorld.jar

It is not necessary to define the Classpath to the program classes, or the support library classes, because it is already defined in the manifest file.

Caution, it is useless to define the Main class at launch, the manifest of the JAR file must contain a line of the form

Main-Class: classname

in order for the -jar option to work JavaDoc.

The syntax for specifying multiple library JAR files in the manifest file is to separate the entries with a space:

Class-Path: lib/supportLib.jar lib/supportLib2.jar

OS specific notes

Being closely associated with the file system, the command-line Classpath syntax depends on the operating system. For example:

  • on all Unix-like operating systems (such as Linux and Mac OS X), the directory structure has a Unix syntax, with separate file paths separated by a colon (":").
  • on Windows, the directory structure has a Windows syntax, and each file path must be separated by a semicolon (";").

This does not apply when the Classpath is defined in manifest files, where each file path must be separated by a space (" "), regardless of the operating system.

Diagnose

Application programmers may want to find out/debug the current settings under which the application is running:

System.getProperty("java.class.path")

本文转载自:http://blog.csdn.net/bluishglc/article/details/9972951

共有 人打赏支持
猪刚烈
粉丝 22
博文 708
码字总数 110
作品 1
海淀
程序员
JAVA环境变量中 classpath、path、JAVA_HOME的作用

..................................................................................................................................................... 1. PATH环境变量。作用是指定......

期待变强的菜鸟
2014/08/24
0
0
Java基础-环境变量设置及Java命令行使用

一、Java环境变量设置 windows 下配置JDK环境变量: 1. 安装JDK,安装过程中可以自定义安装目录等信息,例如我们选择安装目录为D:javajdk1.5.008; 2. 安装完成后,右击“我的电脑”,点击“属...

陶邦仁
2012/11/11
0
0
Exec Maven Plugin全面解析和使用示例

1.为什么使用exec? 现在的工程往往依赖众多的jar包,不像war包工程,对于那些打包成jar包形式的本地java应用来说,通过java命令启动将会是一件极为繁琐的事情,原因很简单,太多的依赖让参数...

劲风online
2015/03/31
0
0
win10下java的jdk安装和环境变量配置

首先需要去JAVA官网下载jdk http://www.oracle.com/technetwork/java/javase/downloads/jdk9-downloads-3848520.html 下载的是jdk 9 与以往的环境配置不一样 jdk是java的核心 是java软件的开...

codingcoge
03/09
0
0
java【jar包的正确运行方式】

-jar参数运行应用时classpath的设置方法 你是否在使用java -jar参数运行打包好的jar应用程序的时候发现应用程序无法找到classpath下设置好的第三方类库的内容?无论怎么设置classpath参数都无...

止静
2014/09/10
0
0

没有更多内容

加载失败,请刷新页面

加载更多

下一页

Nginx防盗链、访问控制、Nginx解析PHP相关配置、Nginx代理

Nginx防盗链 在配置文件里写入以下内容: 用curl测试 访问控制 Nginx限制某些IP不能访问或者只允许某些IP访问。 配置文件写入如下内容: allow 表示允许访问的IP,deny限制访问的IP。 匹配正...

黄昏残影
13分钟前
0
0
自己动手实现RPC服务调用框架

转载 TCP的RPC 引言 本文利用java自带的socket编程实现了一个简单的rpc调用框架,由两个工程组成分别名为battercake-provider(服务提供者)、battercake-consumer(服务调用者)。 设计思路...

雨中漫步的鱼
15分钟前
0
0
Centos6.x安装之后的9件事

Centos6.x安装之后的9件事 这些不是必须都做的,只不过是我个人的习惯,在此记录一下。 1.修改yum源到国内 CentOS系统更换软件安装源 备份你的原镜像文件,以免出错后可以恢复。 mv /etc/yu...

叶云轩
21分钟前
5
0
springboot2 使用jsp NoHandlerFoundException

开发图片上传功能,为验证测试功能是否正常,使用JSP编写表单提交进行测试 开发完成后,请求API提示如下异常: No mapping found for HTTP request with URI [/WEB-INF/jsp/avatar_upload.j...

showlike
26分钟前
0
0
springboot踩坑记--springboot正常启动但访问404

一 spring boot的启动类不能直接放在main(src.java.main)这个包下面,把它放在有包的里面就可以了。 二 正常启动了,但是我写了一个controller ,用的@RestController 注解去配置的controlle...

onedotdot
28分钟前
0
0

没有更多内容

加载失败,请刷新页面

加载更多

下一页

返回顶部
顶部