Java 如何运行 JAR 文件

How to run a JAR file

提问by

I created a JAR file like this:

我创建了一个这样的 JAR 文件：

jar cf Predit.jar *.*

I ran this JAR file by double clicking on it (it didn't work). So I ran it from the DOS prompt like this:

我通过双击运行这个 JAR 文件（它不起作用）。所以我从 DOS 提示符下运行它，如下所示：

java -jar Predit.jar

It raised "Failed to load main class" exceptions. So I extracted this JAR file:

它引发了“无法加载主类”异常。所以我提取了这个 JAR 文件：

jar -xf Predit.jar

and I ran the class file:

我运行了类文件：

java Predit

It worked well. I do not know why the JAR file did not work. Please tell me the steps to run the JAR file

它运作良好。我不知道为什么 JAR 文件不起作用。请告诉我运行JAR文件的步骤

回答by Jon Skeet

You need to specify a Main-Class in the jar file manifest.

您需要在 jar 文件清单中指定一个 Main-Class。

Oracle's tutorialcontains a complete demonstration, but here's another one from scratch. You need two files:

Oracle 的教程包含一个完整的演示，但这里是另一个从头开始的演示。你需要两个文件：

Test.java:

测试.java：

public class Test
{
    public static void main(String[] args)
    {
        System.out.println("Hello world");
    }
}

manifest.mf:

清单.mf：

Manifest-version: 1.0
Main-Class: Test

Note that the text file must end with a new line or carriage return. The last line will not be parsed properly if it does not end with a new line or carriage return.

请注意，文本文件必须以换行符或回车符结尾。如果最后一行没有以新行或回车结束，则不会正确解析。

Then run:

然后运行：

javac Test.java
jar cfm test.jar manifest.mf Test.class
java -jar test.jar

Output:

输出：

Hello world

回答by Florian Fankhauser

You have to add a manifest to the jar, which tells the java runtime what the main class is. Create a file 'Manifest.mf' with the following content:

您必须向 jar 添加一个清单，它告诉 java 运行时主类是什么。使用以下内容创建文件“Manifest.mf”：

Manifest-Version: 1.0
Main-Class: your.programs.MainClass

Change 'your.programs.MainClass' to your actual main class. Now put the file into the Jar-file, in a subfolder named 'META-INF'. You can use any ZIP-utility for that.

将“your.programs.MainClass”更改为您的实际主类。现在将文件放入名为“META-INF”的子文件夹中的 Jar 文件中。您可以为此使用任何 ZIP 实用程序。

回答by fortran

If you don't want to deal with those details, you can also use the export jar assistants from Eclipse or NetBeans.

如果不想处理这些细节，还可以使用 Eclipse 或 NetBeans 中的导出 jar 助手。

回答by Egil

If you don`t want to create a manifest just to run the jar file, you can reference the main-class directly from the command line when you run the jar file.

如果您不想创建清单只是为了运行 jar 文件，则可以在运行 jar 文件时直接从命令行引用主类。

java -jar Predit.jar -classpath your.package.name.Test

This sets the which main-class to run in the jar file.

这将设置在 jar 文件中运行的主类。

回答by Lynch

java -classpath Predit.jar your.package.name.MainClass

回答by Deepa

To run jar, first u have to create

要运行 jar，首先你必须创建

executable jar

可执行jar

then

然后

java -jar xyz.jar

java -jar xyz.jar

command will work

命令会起作用

回答by Mohammad Shahid Siddiqui

Java

爪哇

class Hello{
   public static void main(String [] args){
    System.out.println("Hello Shahid");
   }
}

manifest.mf

清单文件

Manifest-version: 1.0
Main-Class: Hello

On command Line:

在命令行上：

$ jar cfm HelloMss.jar  manifest.mf Hello.class 
$ java -jar HelloMss.jar

Output:

输出：

Hello Shahid

回答by Yash

Eclipse Runnable JAR File

Eclipse 可运行 JAR 文件

Create a Java Project – RunnableJAR

创建一个 Java 项目—— RunnableJAR

• If any jar filesare used then add them to project build path.
• Select the class having main() while creating Runnable Jar file.

• 如果使用了任何jar 文件，则将它们添加到项目构建路径中。
• 在创建 Runnable Jar 文件时选择具有 main() 的类。

Main Class

主类

public class RunnableMainClass {
    public static void main(String[] args) throws InterruptedException {
        System.out.println("Name : "+args[0]);
        System.out.println(" ID  : "+args[1]);
    }
}

Run Jarfile using java program (cmd) by supplying arguments and get the output and display in eclipse console.

通过提供参数使用 java 程序（cmd）运行 Jar文件，并在 eclipse 控制台中获取输出和显示。

public class RunJar { 
    static StringBuilder sb = new StringBuilder();
    public static void main(String[] args) throws IOException {
        String jarfile = "D:\JarLocation\myRunnable.jar";
        String name = "Yash";
        String id = "777";

        try { // jarname arguments has to be saperated by spaces
            Process process = Runtime.getRuntime().exec("cmd.exe start /C java -jar "+jarfile+" "+name+" "+id);
                    //.exec("cmd.exe /C start dir java -jar "+jarfile+" "+name+" "+id+" dir");
            BufferedReader br = new BufferedReader(new InputStreamReader(process.getInputStream ()));
            String line = null;
            while ((line = br.readLine()) != null){
                sb.append(line).append("\n");
            }
            System.out.println("Console OUTPUT : \n"+sb.toString());
            process.destroy();
        }catch (Exception e){
            System.err.println(e.getMessage());
        }
   }
}

In Eclipse to find Short cuts:

在 Eclipse 中找到Shortcuts：

Help ? Help Contents ? Java development user guide ? References ? Menus and Actions

帮助 ？帮助内容 ? Java 开发用户指南 ? 参考 ？菜单和操作

回答by Gabriel D

I have this folder structure:

我有这个文件夹结构：

D:\JavaProjects\OlivePressApp\com\lynda\olivepress\Main.class D:\JavaProjects\OlivePressApp\com\lynda\olivepress\press\OlivePress.class D:\JavaProjects\OlivePressApp\com\lynda\olivepress\olives\Kalamata.class D:\JavaProjects\OlivePressApp\com\lynda\olivepress\olives\Ligurian.class D:\JavaProjects\OlivePressApp\com\lynda\olivepress\olives\Olive.class

D:\JavaProjects\OlivePressApp\com\lynda\olivepress\Main.class D:\JavaProjects\OlivePressApp\com\lynda\olivepress\press\OlivePress.class D:\JavaProjects\OlivePressApp\com\lynda\olivepress\olives\Kalamata .class D:\JavaProjects\OlivePressApp\com\lynda\olivepress\olives\Ligurian.class D:\JavaProjects\OlivePressApp\com\lynda\olivepress\olives\Olive.class

Main.classis in package com.lynda.olivepress

Main.class在包裹里 com.lynda.olivepress

There are two other packages:

还有另外两个包：

com.lynda.olivepress.press

com.lynda.olivepress.olive

com.lynda.olivepress.press

com.lynda.olivepress.olive

1) Create a file named "Manifest.txt"with Two Lines, First with Main-Class and a Second Empty Line.

1）创建一个以"Manifest.txt"两行命名的文件，第一个是主类，第二个是空行。

Main-Class: com.lynda.olivepress.Main

D:\JavaProjects\OlivePressApp\ Manifest.txt

D:\JavaProjects\OlivePressApp\ Manifest.txt

2) Create JAR with Manifest and Main-Class Entry Point

2) 使用 Manifest 和 Main-Class 入口点创建 JAR

D:\JavaProjects\OlivePressApp>jar cfm OlivePressApp.jar Manifest.txt com/lynda/olivepress/Main.class com/lynda/olivepress/*

D:\JavaProjects\OlivePressApp>jar cfm OlivePressApp.jar Manifest.txt com/lynda/olivepress/Main.class com/lynda/olivepress/*

3) Run JAR

3）运行JAR

java -jar OlivePressApp.jar

java -jar OlivePressApp.jar

Note: com/lynda/olivepress/*means including the other two packages mentioned above, before point 1)

注：com/lynda/olivepress/*表示包括上面提到的其他两个包，在第1点之前）

回答by KARTHIKEYAN.A

Before run the jar check Main-Class: classnameis available or not in MANIFEST.MFfile. MANIFEST.MF is present in jar.

在运行之前，检查MANIFEST.MF文件中jar 是否Main-Class: classname可用。MANIFEST.MF 存在于 jar 中。

java -jar filename.jar