public int compile（String file，File workingDirectory）throws IOException，InterruptedException {
ProcessBuilder pb = new ProcessBuilder（javac，file）;
pb.redirectError（）;
pb.directory（new File（workingDirectory））;
进程p = pb.start（）;
InputStreamConsumer consumer = new InputStreamConsumer（p.getInputStream（））;
consumer.start（）;
int result = p.waitFor（）;
consumer.join（）;
System.out.println（consumer.getOutput（））;
返回结果;
public class InputStreamConsumer extends Thread {
private InputStream is;
private IOException exp;
私有StringBuilder输出;
public InputStreamConsumer（InputStream is）{
this.is = is;
@Override
public void run（）{
int in = -1;
output = new StringBuilder（64）; （（in = is.read（））！= -1）{
output.append（（char）in）;
尝试{
。
}
} catch（IOException ex）{
ex.printStackTrace（）;
exp = ex;
public StringBuilder getOutput（）{
return output;
}
public IOException getException（）{
return exp;
$ b你可以使用类似于 compile（PackA / classA.java，new File（/ Users / fnord / Documents / workspace / LearningJava / src ））;
现在，如果你真的很有勇气，你可以看看 >，它使用javax.tools.JavaCompiler类来编译一个Java文件...
So the idea is that this line in the code below
Runtime.getRuntime().exec("cd /Users/fnord/Documents/workspace/LearningJava/src/PackA/; javac classA.java; cd ..; java PackA.classA");
should do the same thing as this line
cd /Users/fnord/Documents/workspace/LearningJava/src/PackA/; javac classA.java; cd ..; java PackA.classA
when that second line is run from a terminal. That is to compile and run the java code. Am I misunderstanding how exec() works? If so, what would be the best way to go about accomplishing what it is I want to accomplish?
package PackA;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
public class classA {
public static void main(String[] args) throws Exception{
ClassLoader loader = classA.class.getClassLoader();
//Sets the file path to the path of the current .java file
File file = new File(loader.getResource(classA.class.getPackage().getName()+"/"+classA.class.getSimpleName()+".class").toString().replaceAll("file:", "").replaceAll("bin", "src").replaceAll("sA.class", "sA.java"));
BufferedReader in = new BufferedReader(new FileReader(file)); //establishes the reader that will be used to read this .java file
StringBuffer string = new StringBuffer(); //the stringBuffer that will be used to hold the contents of this .java file
String stringRead = in.readLine(); //sets a string to the first line of this .java file
while((stringRead) != null){ //as long as we haven't reached the end of the file
string.append(stringRead); //append the line
string.append(System.getProperty("line.separator")); //go to the next line
stringRead = in.readLine(); //read the next line
}
Integer intToFind = new Integer(0); //the integer being looked for
if (intToFind<=10) { //as long as the intToFind is less than or equal to 10
//increment the intToFind in the stringBuffer
StringBuffer newProgram = new StringBuffer(string.toString().replaceFirst("[(]"+intToFind.toString(), "("+String.valueOf(++intToFind)));
//establishes the writer that will be used to write to the file
BufferedWriter out = new BufferedWriter(new FileWriter(file));
out.write(newProgram.toString()); //write the newProgram to this .java file with the incremented intToFind
in.close(); //close both the reader and writer
out.close();
//Go to the directory of the java file, compile the code, move down one directory, execute the .class file
Runtime.getRuntime().exec("cd /Users/fnord/Documents/workspace/LearningJava/src/PackA/; javac classA.java; cd ..; java PackA.classA");
}
}
}
解决方案
cd is not a program, it's a shell command.
You could use ProcessBuilder instead, which would allow you to define the working directory context from which the command should be executed
Something like this for example
Abbriviated code from previous example, updated to provide the ability to specifiy the working directory
public int compile(String file, File workingDirectory) throws IOException, InterruptedException {
ProcessBuilder pb = new ProcessBuilder("javac", file);
pb.redirectError();
pb.directory(new File(workingDirectory));
Process p = pb.start();
InputStreamConsumer consumer = new InputStreamConsumer(p.getInputStream());
consumer.start();
int result = p.waitFor();
consumer.join();
System.out.println(consumer.getOutput());
return result;
}
public class InputStreamConsumer extends Thread {
private InputStream is;
private IOException exp;
private StringBuilder output;
public InputStreamConsumer(InputStream is) {
this.is = is;
}
@Override
public void run() {
int in = -1;
output = new StringBuilder(64);
try {
while ((in = is.read()) != -1) {
output.append((char) in);
}
} catch (IOException ex) {
ex.printStackTrace();
exp = ex;
}
}
public StringBuilder getOutput() {
return output;
}
public IOException getException() {
return exp;
}
}
Which you could call using something like...
compile("PackA/classA.java", new File("/Users/fnord/Documents/workspace/LearningJava/src"));
Now, if you're really courageous, you could take a look at How do you dynamically compile and load external java classes?, which uses javax.tools.JavaCompiler` class to compile a Java file...
这篇关于在Java中使用exec编译和执行失败，使用命令行的命令的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！
