问题

IDE使用：IntelliJ
系统操作系统：Windows
尝试的命令：ProcessBuilder，Runtime.exec()

我正在执行Main.java文件（如下所示）。在终端中它可以完美运行，但在IntelliJ中会抛出以下错误。无论是使用ProcessBuilder还是Runtime.exec()都会出现相同的情况。

"C:\Program Files\Java\jdk1.8.0_241\bin\java.exe"
Exception in thread "main" java.io.IOException: Cannot run program "echo"：CreateProcess error=2，系统找不到指定的文件。
	at java.lang.ProcessBuilder.start(ProcessBuilder.java:1048)
	at TestSample.Main.main(Main.java:24)
Caused by: java.io.IOException: CreateProcess error=2，系统找不到指定的文件。
	at java.lang.ProcessImpl.create(Native Method)
	at java.lang.ProcessImpl.<init>(ProcessImpl.java:444)
	at java.lang.ProcessImpl.start(ProcessImpl.java:140)
	at java.lang.ProcessBuilder.start(ProcessBuilder.java:1029)
	... 1 more

Process finished with exit code 1

为什么会发生这种情况？有人能帮我解决这个问题吗？

Main.java

```
public static void main(String[] args) throws InterruptedException,IOException{

    ProcessBuilder builder = new ProcessBuilder("echo", "This is ProcessBuilder Example");
    Process p=builder.start();
    int errcode = p.waitFor();
    System.out.println("程序是否成功执行？" + (errcode == 0 ? "否" : "是"));
    System.out.println("Echo输出：\n" + output(p.getInputStream()));

}
private static String output(InputStream inputStream) throws IOException {
    StringBuilder sb = new StringBuilder();
    BufferedReader br = null;
    try {
        br = new BufferedReader(new InputStreamReader(inputStream));
        String line = null;
        while ((line = br.readLine()) != null) {
            sb.append(line + System.getProperty("line.separator"));
        }
    } finally {
        br.close();
    }
    return sb.toString();
}

此代码来源于https://examples.javacodegeeks.com/core-java/lang/processbuilder/java-lang-processbuilder-example/

<details>
<summary>英文:</summary>

IDE used: IntelliJ &lt;br&gt;
System OS: Windows &lt;br&gt;
Commands tried: ProcessBuilder, Runtime.exec()

I am executing &lt;a href=&quot;#JavaFile&quot;&gt;Main.java&lt;/a&gt; file (mentioned below). It executes perfectly in terminal but in IntelliJ, it throws the following error. The same happens with both ProcessBuilder and Runtime.exec().&lt;br&gt;

"C:\Program Files\Java\jdk1.8.0_241\bin\java.exe"
Exception in thread "main" java.io.IOException: Cannot run program "echo": CreateProcess error=2, The system cannot find the file specified
at java.lang.ProcessBuilder.start(ProcessBuilder.java:1048)
at TestSample.Main.main(Main.java:24)
Caused by: java.io.IOException: CreateProcess error=2, The system cannot find the file specified
at java.lang.ProcessImpl.create(Native Method)
at java.lang.ProcessImpl.<init>(ProcessImpl.java:444)
at java.lang.ProcessImpl.start(ProcessImpl.java:140)
at java.lang.ProcessBuilder.start(ProcessBuilder.java:1029)
... 1 more

Process finished with exit code 1

Why is it happening? Can someone help me resolve this issue? <br>

<h2 id="JavaFile"><b>Main.java</b></h2>

public static void main(String[] args) throws InterruptedException,IOException{

    ProcessBuilder builder = new ProcessBuilder("echo", "This is ProcessBuilder Example");
    Process p=builder.start();
    int errcode = p.waitFor();
    System.out.println("Program is executed successfully?"+(errcode == 0 ?"No":"Yes"));
    System.out.println("Echo Output:\n" + output(p.getInputStream()));

}
private static String output(InputStream inputStream) throws IOException {
    StringBuilder sb = new StringBuilder();
    BufferedReader br = null;
    try {
        br = new BufferedReader(new InputStreamReader(inputStream));
        String line = null;
        while ((line = br.readLine()) != null) {
            sb.append(line + System.getProperty("line.separator"));
        }
    } finally {
        br.close();
    }
    return sb.toString();
}

This code is retrieved from https://examples.javacodegeeks.com/core-java/lang/processbuilder/java-lang-processbuilder-example/

</details>


# 答案1
**得分**: 3

`echo` 不是一个有效的可执行文件，而是由命令行 shell (`cmd.exe`) 提供的命令。

为了从其他进程中运行这个命令，您需要启动 `cmd.exe` 并将参数传递给它。

在 Windows 中，正常工作的代码如下所示：

```java
ProcessBuilder pb = new ProcessBuilder("cmd.exe", "/C", "echo", "This is ProcessBuilder Example from JCG");

对于其他操作系统，您需要将 cmd.exe 替换为 /bin/bash 等。

ProcessBuilder pb = new ProcessBuilder("cmd.exe", "/C", "echo", "This is ProcessBuilder Example from JCG");