java - 可能原因 java.io.IOException : CreateProcess error=2, 系统找不到指定的文件

Question

我正在尝试通过 java 执行“VACUUM VERBOSE”命令。这是我的代码

public void executeCommand()
{
    String cmd1= "cmd.exe /c start";
    String location="C:\\PROGRA~1\\PostgreSQL\\8.3\\bin\\";
    String postgresCommand="psql -h localhost -U postgres -d postgres";
    String autoVaccum="-c \"vacuum verbose\"";
    String []actualCmd={cmd1,location,postgresCommand,autoVaccum};

    Process process=null;
    try {
        process = Runtime.getRuntime().exec(actualCmd);
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}


public static void main(String[] args) {
    MyTest test= new MyTest();
    test.executeCommand();

}

但是我遇到了以下异常

java.io.IOException: Cannot run program "cmd.exe /c start": CreateProcess error=2, The system cannot find the file specified
    at java.lang.ProcessBuilder.start(Unknown Source)
    at java.lang.Runtime.exec(Unknown Source)
    at java.lang.Runtime.exec(Unknown Source)
    at MyTest.executeCommand(MyTest.java:36)
    at MyTest.main(MyTest.java:48)
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>(Unknown Source)
    at java.lang.ProcessImpl.start(Unknown Source)
    ... 5 more

当我直接在“开始”->“运行”窗口中直接键入上述字符串时，它会成功执行例如。cmd.exe/C start C:\PROGRA~1/PostgreSQL/8.3/bin/psql -h localhost -U postgres -d postgres -c "vacuum verbose"

有人能知道上面的程序到底出了什么问题吗？

Answer 1

有多种方法可以调用 exec()。您正在使用的 on 以 String[] 作为参数，期望每个标记位于数组的不同部分。所以呼吁

Runtime.getRuntime().exec("cmd /c start executable arg1 arg2");

当使用数组而不是一个字符串调用时，称为

Process p = Runtime.getRuntime().exec(new String[]{"cmd","/c","start","executable","arg1","arg2");    
BufferedReader inReader = new BufferedReader(new InputStreamReader(p.getInputStream()));
BufferedWriter outWriter = new BufferedWriter(new OutputStreamWriter(p.getOutputStream()));

exec() 返回一个 Process 对象，然后您可以使用 getInputStream() 获取该对象的输出。这实际上是该过程的输出，它是 java 代码的输入。然后，您可以像任何其他流一样读取它，并根据需要将其显示给用户。