java ProcessBuilder 与 Runtime.exec()
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ProcessBuilder vs Runtime.exec()
提问by blastthisinferno
I'm trying to create a frontend app in Java to handle batch SVG conversions using Inkscape's command line feature. I'm taking and updating the code from https://sourceforge.net/projects/conversionsvg/. The way the original developer handled calling Inkscape by Runtime.getRuntime().exec(String). The issue I'm running into is some inconsistencies between using methodA and methodB. I created a simple java test project to demonstrate the different actions being performed.
我正在尝试在 Java 中创建一个前端应用程序，以使用 Inkscape 的命令行功能处理批量 SVG 转换。我正在从https://sourceforge.net/projects/conversionsvg/获取和更新代码。原始开发人员通过Runtime.getRuntime().exec(String)处理调用 Inkscape 的方式。我遇到的问题是使用方法 A 和方法 B 之间存在一些不一致。我创建了一个简单的 java 测试项目来演示正在执行的不同操作。
CallerTest.java
调用者测试程序
package conversion;
import java.io.IOException;
public class CallerTest {
static String pathToInkscape = "\"C:\Program Files\Inkscape\inkscape.exe\"";
public static void main(String[] args) {
ProcessBuilderCaller processBuilder = new ProcessBuilderCaller();
RuntimeExecCaller runtimeExec = new RuntimeExecCaller();
// methodA() uses one long command line string
try {
String oneLongString_ProcessBuilder = pathToInkscape + " -f \"C:\test.svg\" -D -w 100 -h 100 -e \"C:\ProcessBuilder-methodB.png\"";
String oneLongString_RuntimeExec = pathToInkscape + " -f \"C:\test.svg\" -D -w 100 -h 100 -e \"C:\RuntimeExec-methodA.png\"";
// processBuilder.methodA(oneLongString_ProcessBuilder);
runtimeExec.methodA(oneLongString_RuntimeExec);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// methodB() uses an array containing the command and the options to pass to the command
try {
String[] commandAndOptions_ProcessBuilder = {pathToInkscape, " -f \"C:/test.svg\" -D -w 100 -h 100 -e \"C:\ProcessBuilder-methodB.png\""};
String[] commandAndOptions_RuntimeExec = {pathToInkscape, " -f \"C:/test.svg\" -D -w 100 -h 100 -e \"C:\RuntimeExec-methodB.png\""};
processBuilder.methodB(commandAndOptions_ProcessBuilder);
// runtimeExec.methodB(commandAndOptions_RuntimeExec);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
RuntimeExecCaller.java
运行时执行调用程序
package conversion;
import java.io.IOException;
public class RuntimeExecCaller {
Process process;
// use one string
public void methodA(String oneLongString) throws IOException {
process = Runtime.getRuntime().exec(oneLongString);
}
// use the array
public void methodB(String[] commandAndOptions) throws IOException {
process = Runtime.getRuntime().exec(commandAndOptions);
}
}
ProcessBuilderCaller.java
ProcessBuilderCaller.java
package conversion;
import java.io.IOException;
public class ProcessBuilderCaller {
Process process;
// use one string
public void methodA(String oneLongString) throws IOException {
process = new ProcessBuilder(oneLongString).start();
}
// use the array
public void methodB(String[] commandAndOptions) throws IOException {
process = new ProcessBuilder(commandAndOptions).start();
}
}
Result
结果
Both methodA(String)calls work, but when methodB(String[])is called Inkscape is being started and the arguments are being passed incorrectly. After methodB(String[])executes I get an Inkscape error dialog for each saying
两个methodA(String)调用都有效，但是当调用methodB(String[]) 时，Inkscape 正在启动并且参数传递不正确。在methodB(String[])执行后，我会为每个说法得到一个Inkscape 错误对话框
Failed to load the requested file -f C:/test.svg -D -w 100 -h 100 -e C:\RuntimeExec-methodB.png
Failed to load the requested file -f C:/test.svg -D -w 100 -h 100 -e C:\ProcessBuilder-methodB.png
无法加载请求的文件 -f C:/test.svg -D -w 100 -h 100 -e C:\RuntimeExec-methodB.png
无法加载请求的文件 -f C:/test.svg -D -w 100 -h 100 -e C:\ProcessBuilder-methodB.png
and when I click Close on the dialog, Inkscape pops up with a new blank document. So, I guess I have a few questions:
当我单击对话框上的关闭时，Inkscape 会弹出一个新的空白文档。所以，我想我有几个问题：
What is the difference between Runtime.getRuntime().exec(String) and Runtime.getRuntime().exec(String[])?
Runtime.getRuntime().exec(String) 和 Runtime.getRuntime().exec(String[]) 有什么区别？
JavaDoc says that Runtime.exec(String)calls Runtime.exec(command, null)(which is Runtime.exec(String cmd, String[] envp)) which in turn calls Runtime.exec(cmdarray, envp)(which is Runtime.exec(String[] cmdarray, String[] envp)). So, if Runtime.getRuntime().exec(String)is calling Runtime.exec(String[])anyways, why am I getting different results when using different methods?
JavaDoc 说Runtime.exec(String)调用Runtime.exec(command, null)（即Runtime.exec(String cmd, String[] envp)），后者又调用Runtime.exec(cmdarray, envp)（即Runtime .exec(String[] cmdarray, String[] envp))。因此，如果Runtime.getRuntime().exec(String)无论如何都在调用Runtime.exec(String[])，为什么在使用不同的方法时会得到不同的结果？
Is something happening behind the scenes where Java sets up the environment differently depending on which method is called?
是否在幕后发生了一些事情，其中 Java 根据调用的方法来设置不同的环境？
回答by userkci
I suspect your problem stems from the way you're specifying your argument list. Essentially, you're passing "-f C:/test.svg -D -w 100 -h 100 -e C:\RuntimeExec-methodB.png" as one single argumentto Inkscape.
我怀疑您的问题源于您指定参数列表的方式。本质上，您将“ -f C:/test.svg -D -w 100 -h 100 -e C:\RuntimeExec-methodB.png”作为一个参数传递给 Inkscape。
What you need to do is pass the arguments individually, like so:
您需要做的是单独传递参数，如下所示：
String[] commandAndOptions_ProcessBuilder = {pathToInkscape, "-f", "C:\est.svg", "-D", "-w", "100", "-h", "100", "-e", "C:\ProcessBuilder-methodB.png"};
String[] commandAndOptions_RuntimeExec = {pathToInkscape, "-f", "C:\test.svg", "-D", "-w", "100", "-h", "100", "-e","C:\RuntimeExec-methodB.png"};
Roughly speaking, when you use Runtime.exec(String), the value you pass in gets evaluated by the shell, which parses out the argument list. When you use Runtime.exec(String[]), you're providing the argument list, so it doesn't need processing. A benefit of doing this is that you don't have to escape values special to the shell, as the arguments will not be evaluated by it.
粗略地说，当您使用 时Runtime.exec(String)，您传入的值由外壳程序评估，外壳程序会解析出参数列表。使用时Runtime.exec(String[])，您提供的是参数列表，因此不需要处理。这样做的一个好处是您不必转义 shell 特有的值，因为参数不会被它评估。
