1 /*
2 * Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24 package jdk.test.lib;
25
26 import java.io.ByteArrayOutputStream;
27 import java.io.IOException;
28 import java.io.OutputStream;
29
30 import java.net.URI;
31 import java.util.Arrays;
32
33 import javax.tools.ForwardingJavaFileManager;
34 import javax.tools.FileObject;
35 import javax.tools.JavaCompiler;
36 import javax.tools.JavaCompiler.CompilationTask;
37 import javax.tools.JavaFileObject;
38 import javax.tools.JavaFileObject.Kind;
39 import javax.tools.SimpleJavaFileObject;
40 import javax.tools.ToolProvider;
41
42 /**
43 * {@code InMemoryJavaCompiler} can be used for compiling a {@link
44 * CharSequence} to a {@code byte[]}.
45 *
46 * The compiler will not use the file system at all, instead using a {@link
47 * ByteArrayOutputStream} for storing the byte code. For the source code, any
48 * kind of {@link CharSequence} can be used, e.g. {@link String}, {@link
49 * StringBuffer} or {@link StringBuilder}.
50 *
51 * The {@code InMemoryCompiler} can easily be used together with a {@code
52 * ByteClassLoader} to easily compile and load source code in a {@link String}:
53 *
54 * <pre>
55 * {@code
56 * import jdk.test.lib.InMemoryJavaCompiler;
57 * import jdk.test.lib.ByteClassLoader;
58 *
59 * class Example {
60 * public static void main(String[] args) {
61 * String className = "Foo";
62 * String sourceCode = "public class " + className + " {" +
63 * " public void bar() {" +
64 * " System.out.println("Hello from bar!");" +
65 * " }" +
66 * "}";
67 * byte[] byteCode = InMemoryJavaCompiler.compile(className, sourceCode);
68 * Class fooClass = ByteClassLoader.load(className, byteCode);
69 * }
70 * }
71 * }
72 * </pre>
73 */
74 public class InMemoryJavaCompiler {
75 private static class MemoryJavaFileObject extends SimpleJavaFileObject {
76 private final String className;
77 private final CharSequence sourceCode;
78 private final ByteArrayOutputStream byteCode;
79
80 public MemoryJavaFileObject(String className, CharSequence sourceCode) {
81 super(URI.create("string:///" + className.replace('.','/') + Kind.SOURCE.extension), Kind.SOURCE);
82 this.className = className;
83 this.sourceCode = sourceCode;
84 this.byteCode = new ByteArrayOutputStream();
85 }
86
87 @Override
88 public CharSequence getCharContent(boolean ignoreEncodingErrors) {
89 return sourceCode;
90 }
91
92 @Override
93 public OutputStream openOutputStream() throws IOException {
94 return byteCode;
95 }
96
97 public byte[] getByteCode() {
98 return byteCode.toByteArray();
99 }
100
101 public String getClassName() {
102 return className;
103 }
104 }
105
106 private static class FileManagerWrapper extends ForwardingJavaFileManager {
107 private MemoryJavaFileObject file;
108
109 public FileManagerWrapper(MemoryJavaFileObject file) {
110 super(getCompiler().getStandardFileManager(null, null, null));
111 this.file = file;
112 }
113
114 @Override
115 public JavaFileObject getJavaFileForOutput(Location location, String className,
116 Kind kind, FileObject sibling)
117 throws IOException {
118 if (!file.getClassName().equals(className)) {
119 throw new IOException("Expected class with name " + file.getClassName() +
120 ", but got " + className);
121 }
122 return file;
123 }
124 }
125
126 /**
127 * Compiles the class with the given name and source code.
128 *
129 * @param className The name of the class
130 * @param sourceCode The source code for the class with name {@code className}
131 * @throws RuntimeException if the compilation did not succeed
132 * @return The resulting byte code from the compilation
133 */
134 public static byte[] compile(String className, CharSequence sourceCode) {
135 MemoryJavaFileObject file = new MemoryJavaFileObject(className, sourceCode);
136 CompilationTask task = getCompilationTask(file);
137
138 if(!task.call()) {
139 throw new RuntimeException("Could not compile " + className + " with source code " + sourceCode);
140 }
141
142 return file.getByteCode();
143 }
144
145 private static JavaCompiler getCompiler() {
146 return ToolProvider.getSystemJavaCompiler();
147 }
148
149 private static CompilationTask getCompilationTask(MemoryJavaFileObject file) {
150 return getCompiler().getTask(null, new FileManagerWrapper(file), null, null, null, Arrays.asList(file));
151 }
152 }