java - 从另一个java类编译java文件

Question

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class ExecuteShellComand {

    public static void main(String[] args) {

        ExecuteShellComand obj = new ExecuteShellComand();
        String className = "str.java";
        String command = "javac " + className;
        String output = obj.executeCommand(command);
        System.out.println(output);// prints the output of the executed command
    }

    private String executeCommand(String command) {
        StringBuffer output = new StringBuffer();
        Process p;
        try {
            p = Runtime.getRuntime().exec(command);
            p.waitFor();
            BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
            String line = "";
            while ((line = reader.readLine()) != null) {
                output.append(line + "\n");
            }

        } catch (Exception e) {
            e.printStackTrace();
        }

        return output.toString();

    }

}

我正在尝试从另一个 Java 类 (ExecuteShellComand.java) 编译 Java 文件 (str.java)。我想做的是，如果“str.java”编译成功，那么我想执行“java str”命令，但如果编译失败，则应打印正确的堆栈跟踪或错误。我将堆栈跟踪或错误存储在 output 变量中。

但是当我执行此代码时，尽管“str.java”有一些错误 System.out.println(output) 不会打印错误。

Answer 1

如果你想捕获命令中的错误，那么你应该捕获错误流而不是输入流

所以替换

BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));

与

BufferedReader reader = new BufferedReader(new InputStreamReader(p.getErrorStream()));