java1.6 动态编译代码的例子

package demo;import javax.lang.model.element.Modifier;import javax.lang.model.element.NestingKind;import javax.tools.JavaCompiler;import javax.tools.JavaFileObject;import javax.tools.SimpleJavaFileObject;import javax.tools.StandardJavaFileManager;import javax.tools.ToolProvider;import javax.tools.JavaFileObject.Kind;import java.io.IOException;import java.lang.reflect.Method;import java.net.URI;import java.util.Arrays;public class CompileString {    public static void main(String[] args) throws Exception {        //通过系统工具提供者获得动态编译器        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();        //获得一个文件管理器，它的功能主要是提供所有文件操作的规则，       //如源代码路径、编译的classpath，class文件目标目录等，其相关属性都提供默认值        StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, null, null);        StringObject so = new StringObject("demo.CalculatorTest", "package demo;" +                "  class CalculatorTest {" +                "public int multiply(int multiplicand, int multiplier) {" +                "System.out.println(multiplicand);" +                "System.out.println(multiplier);" +                "return multiplicand * multiplier;" +                "}" +                "}");        JavaFileObject file = so;        // 指定 javac 的命令行参数        // 注意：最好将编译后的.class文件放到当前JVM实例的类路径上，否则加载不鸟        Iterable options = Arrays.asList("-d", "E:\\workspace\\hellosbt\\target\\scala-2.9.1\\classes");        // 指定有哪些源文件需要被编译        Iterable<? extends JavaFileObject> files = Arrays.asList(file);                JavaCompiler.CompilationTask task = compiler.getTask(null, fileManager, null, options, null, files);        Boolean result = task.call();               if (result) {            System.out.println("编译成功");            Class<?> clazz = Class.forName("demo.CalculatorTest");            Object instance = clazz.newInstance();            Method m = clazz.getMethod("multiply", new Class[]{int.class, int.class});            Object[] o = new Object[]{1, 2};            m.invoke(instance, o);        }    }}class StringObject extends SimpleJavaFileObject {    private String contents = null;    public StringObject(String className, String contents) throws Exception {        super(new URI(className), Kind.SOURCE);        this.contents = contents;    }    public CharSequence getCharContent(boolean ignoreEncodingErrors) throws IOException {        return contents;    }}