Python exec()学习

exec语句用来执行存储在字符串或文件中的Python语句，当时学java时就不断想，如果一个方法不断读取自己的内容然后去执行读取到的内容，那应该是一件很有意思的事情

今天学习Python时看到了exec，惊为神器，怎么会有这么好的方法，于是果断去实现自己的想法

下面是我的代码，欢迎批评指正

?

1 2 3 4 5 6 7 8 9 10 11 12 13

#!/usr/bin/python import time print('yes.i can') time.sleep(1) f = file('/home/t.py') while True:     line = f.readline()     if(len(line)==1):       break     else:       exec(line) f.close()

先执行一条打印，然后再去休眠两秒，最后再读取自己文件的内容去执行，可以得到一个死循环

于是我在想java应该也有类似的功能。去网上搜还真找到了

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51

package myPcg6; import java.io.IOException; import java.net.URI; import java.net.URISyntaxException; import java.util.Arrays; import java.util.List;   import javax.tools.JavaCompiler; import javax.tools.SimpleJavaFileObject; import javax.tools.StandardJavaFileManager; import javax.tools.ToolProvider; import javax.tools.JavaCompiler.CompilationTask;   public class CompilerTest {             public static void main(String[] args) throws Exception {              String source = "public class Main {" +                                "public static void main(String[] args) {" +                                    "System.out.println(\"Hello World!\");" +                                 "} " +                            "}";                                JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();        StandardJavaFileManager fileManager =  compiler.getStandardFileManager(null, null, null);        StringSourceJavaObject sourceObject = new CompilerTest.StringSourceJavaObject("Main", source);        List<StringSourceJavaObject> fileObjects =  Arrays.asList(sourceObject);        CompilationTask task = compiler.getTask(null, fileManager, null, null, null, fileObjects);                 boolean result = task.call();        if (result) {           System.out.println("Compile succeeded!");        }  else {           System.out.println("Compile failed!");        }     }         static class StringSourceJavaObject extends SimpleJavaFileObject {            private String content = null;        public StringSourceJavaObject(String name, String content) throws URISyntaxException {           super(URI.create("string:///" + name.replace('.','/') +  Kind.SOURCE.extension), Kind.SOURCE);           this.content = content;        }            @Override        public CharSequence getCharContent(boolean ignoreEncodingErrors) throws IOException {           return content;        }     }  }

　　上面是某个大神的代码，http://www.cnblogs.com/fangwenyu/archive/2011/10/12/2209051.html，里面说的很详细，当然这只是工具，会用即可

从上面忽然想到，原来秋招时考试提交的代码大概就是这么处理的吧