jdk8-mips64-public/langtools: test/tools/javac/api/evalexpr/CompileFromString.java@7909abb85562 (annotated)

test/tools/javac/api/evalexpr/CompileFromString.java@7909abb85562 (annotated)

test/tools/javac/api/evalexpr/CompileFromString.java

Wed, 14 Nov 2018 10:18:25 -0800

author: diazhou
date: Wed, 14 Nov 2018 10:18:25 -0800
changeset 3762: 7909abb85562
parent 581: f2fdd52e4e87
child 2525: 2eb010b6cb22
permissions: -rw-r--r--

Added tag jdk8u201-b04 for changeset a7f48b9dfb82

 /*
  * Copyright (c) 2005, 2006, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */
 package evalexpr;
 import java.lang.reflect.Method;
 import java.util.*;
 import javax.swing.JOptionPane;
 import javax.tools.*;
 import static javax.tools.StandardLocation.CLASS_OUTPUT;
 /**
  * JSR 199 Demo application: compile from a String.
  *
  * <p><b>This is NOT part of any supported API.
  * If you write code that depends on this, you do so at your own
  * risk.  This code and its internal interfaces are subject to change
  * or deletion without notice.</b></p>
  *
  * @author Peter von der Ah&eacute;
  */
 public class CompileFromString {
     /**
      * The name of the class used to evaluate expressions.
      */
     private final static String CLASS_NAME = "EvalExpression";
     /**
      * Object used to signal errors from evalExpression.
      */
     public final static Object ERROR = new Object() {
         public String toString() { return "error"; }
     };
     /**
      * Compile and evaluate the specified expression using the
      * given compiler.
      * @param compiler a JSR 199 compiler tool used to compile the given expression
      * @param expression a Java Programming Language expression
      * @return the value of the expression; ERROR if any errors occured during compilation
      * @throws java.lang.Exception exceptions are ignored for brevity
      */
     public static Object evalExpression(JavaCompiler compiler,
                                         DiagnosticListener<JavaFileObject> listener,
                                         List<String> flags,
                                         String expression)
         throws Exception
     {
         // Use a customized file manager
         MemoryFileManager mfm =
             new MemoryFileManager(compiler.getStandardFileManager(listener, null, null));
         // Create a file object from a string
         JavaFileObject fileObject = mfm.makeSource(CLASS_NAME,
             "public class " + CLASS_NAME + " {\n" +
             "    public static Object eval() throws Throwable {\n" +
             "        return " + expression + ";\n" +
             "    }\n}\n");
         JavaCompiler.CompilationTask task =
             compiler.getTask(null, mfm, listener, flags, null, Arrays.asList(fileObject));
         if (task.call()) {
             // Obtain a class loader for the compiled classes
             ClassLoader cl = mfm.getClassLoader(CLASS_OUTPUT);
             // Load the compiled class
             Class compiledClass = cl.loadClass(CLASS_NAME);
             // Find the eval method
             Method eval = compiledClass.getMethod("eval");
             // Invoke it
             return eval.invoke(null);
         } else {
             // Report that an error occured
             return ERROR;
         }
     }
     /**
      * Main entry point for program; ask user for expressions,
      * compile, evaluate, and print them.
      *
      * @param args ignored
      * @throws java.lang.Exception exceptions are ignored for brevity
      */
     public static void main(String... args) throws Exception {
         // Get a compiler tool
         final JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
         final List<String> compilerFlags = new ArrayList();
         compilerFlags.add("-Xlint:all"); // report all warnings
         compilerFlags.add("-g:none"); // don't generate debug info
         String expression = "System.getProperty(\"java.vendor\")";
         while (true) {
             expression = JOptionPane.showInputDialog("Please enter a Java expression",
                                                      expression);
             if (expression == null)
                 return; // end program on "cancel"
             long time = System.currentTimeMillis();
             Object result = evalExpression(compiler, null, compilerFlags, expression);
             time = System.currentTimeMillis() - time;
             System.out.format("Elapsed time %dms %n", time);
             if (result == ERROR)
                 System.out.format("Error compiling \"%s\"%n", expression);
             else
                 System.out.format("%s => %s%n", expression, result);
         }
     }
 }

Mercurial > jdk8-mips64-public > langtools / annotate

test/tools/javac/api/evalexpr/CompileFromString.java@7909abb85562 (annotated)

test/tools/javac/api/evalexpr/CompileFromString.java