JavaComplier的使用

来源：互联网发布：谱尼测试工作强度知乎编辑：程序博客网时间：2024/06/05 14:12
JDK1.6提供了JavaCompiler类，此类可以允许开发人员编译java文件为class文件。
import javax.tools.JavaCompiler;import javax.tools.JavaCompiler.*;import javax.tools.StandardJavaFileManager;import javax.tools.ToolProvider;import java.io.File;import java.io.FileWriter;import java.io.IOException;import java.net.URL;import java.net.URLClassLoader;/** * Created by admin on 2017/7/31. */public class DefComplier {    public static final String  code = "package TestComplier;\n" +            "\n" +            "/**\n" +            " * Created by admin on 2017/7/31.\n" +            " */\n" +            "class HelloWorld {\n" +            "    public void say(){\n" +            "        System.out.println(\"Hello World\");\n" +            "    }\n" +            "}";    public static final String currentPath = System.getProperty("user.dir");    public static final String fileName = currentPath+"/src/TestComplier/HelloWorld.java";    public static void main(String[] args) {        DefComplier dc = new DefComplier();        dc.writeFile();        try {            dc.complier();            dc.loadClazz();        }catch (Exception e){            e.printStackTrace();        }    }    /*把字符串写成java文件*/    public void writeFile(){        File file = new File(fileName);        try{            FileWriter fw = new FileWriter(file);            fw.write(code);            fw.flush();            fw.close();        }catch (IOException e){            e.printStackTrace();        }    }    /*编译文件*/    public void complier() throws Exception{        //获得系统编译器，如果使用jre（运行环境）则无法获得编译器        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();        System.out.println(compiler.getClass().getName());        //获得文件管理器        StandardJavaFileManager fileManager = compiler.getStandardFileManager(null,null,null);        //可以得到多个可迭代的编译对象        Iterable Files = fileManager.getJavaFileObjects(fileName);        //获得编译任务        CompilationTask t = compiler.getTask(null,fileManager,null,null,null,Files);        //开始编译，得到class文件        t.call();        fileManager.close();    }    /*把class文件加载到内存*/    /*URLClASSloader加载器用于从指向 JAR 文件和目录的 URL 的搜索路径加载类和资源。*/    public void loadClazz() throws Exception {        URL[] urls = new URL[]{new URL("file:/" + currentPath + "/src/")};        ClassLoader loader = new URLClassLoader(urls);        Class clazz = loader.loadClass("TestComplier.HelloWorld");        HelloWorld h = (HelloWorld)clazz.newInstance();        h.say();    }}
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