开发一个工具类,该工具类提供一个eva（）方法,实现Java

/** * Java创建一个类似于js中eval()的方法 */ public class EvalUtil { public static void main(String[] args) throws Exception { eval("int a = c; int b = 2; System.out.println(a+b);"); } public static void eval(String javaStr) throws Exception { StringBuffer str = new StringBuffer(); str.append("public class Eval {").append("public static void main(String[] args) {").append(javaStr).append("}}"); OutputStream out = new FileOutputStream("Eval.java"); out.write(str.toString().getBytes("gbk")); out.close(); // 编译时 错误信息 Process javacProcess = Runtime.getRuntime().exec("javac Eval.java"); InputStream compileError = javacProcess.getErrorStream(); System.err.println(read(compileError)); compileError.close(); Process javaProcess = Runtime.getRuntime().exec("java Eval"); //运行时 错误信息 InputStream err = javaProcess.getErrorStream(); System.err.println(read(err)); err.close(); //运行时 正常信息 InputStream success = javaProcess.getInputStream(); System.out.println(read(success)); success.close(); //删除生成文件 new File("Eval.java").delete(); new File("Eval.class").delete(); } private static String read(InputStream in) throws IOException { byte[] b = new byte[1024]; int len = -1; StringBuffer str = new StringBuffer(); while ((len = in.read(b)) != -1) { str.append(new String(b, 0, len, "gbk")); } return str.toString(); } }