1 package org.codehaus.plexus.languages.java.version;
2
3 import java.io.IOException;
4 import java.io.InputStream;
5 import java.io.UncheckedIOException;
6 import java.nio.file.Files;
7 import java.nio.file.Path;
8
9 /*
10 * Licensed to the Apache Software Foundation (ASF) under one
11 * or more contributor license agreements. See the NOTICE file
12 * distributed with this work for additional information
13 * regarding copyright ownership. The ASF licenses this file
14 * to you under the Apache License, Version 2.0 (the
15 * "License"); you may not use this file except in compliance
16 * with the License. You may obtain a copy of the License at
17 *
18 * http://www.apache.org/licenses/LICENSE-2.0
19 *
20 * Unless required by applicable law or agreed to in writing,
21 * software distributed under the License is distributed on an
22 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
23 * KIND, either express or implied. See the License for the
24 * specific language governing permissions and limitations
25 * under the License.
26 */
27
28 /**
29 * Reads the bytecode of a Java class to detect the major, minor and Java
30 * version that was compiled.
31 *
32 * @author Jorge Solórzano
33 */
34 public final class JavaClassfileVersion {
35
36 private final int major;
37 private final int minor;
38
39 JavaClassfileVersion(int major, int minor) {
40 if (major < 45) {
41 throw new IllegalArgumentException("Java class major version must be 45 or above.");
42 }
43 this.major = major;
44 this.minor = minor;
45 }
46
47 /**
48 * Reads the bytecode of a Java class file and returns the
49 * {@link JavaClassfileVersion}.
50 *
51 * @param bytes {@code byte[]} of the Java class file
52 * @return the {@link JavaClassfileVersion} of the byte array
53 */
54 public static JavaClassfileVersion of(byte[] bytes) {
55 return JavaClassfileVersionParser.of(bytes);
56 }
57
58 /**
59 * Reads the bytecode of a Java class file and returns the
60 * {@link JavaClassfileVersion}.
61 *
62 * @param path {@link Path} of the Java class file
63 * @return the {@link JavaClassfileVersion} of the path java class
64 */
65 public static JavaClassfileVersion of(Path path) {
66 try (InputStream is = Files.newInputStream(path)) {
67 byte[] bytes = new byte[8];
68 int total = 0;
69 while (total < 8) {
70 int l = is.read(bytes, total, 8 - total);
71 if (l > 0) {
72 total += l;
73 }
74 if (l == -1) {
75 break;
76 }
77 }
78 return of(bytes);
79 } catch (IOException ex) {
80 throw new UncheckedIOException(ex);
81 }
82 }
83
84 /**
85 * JavaVersion of the class file version detected.
86 *
87 * @return JavaVersion based on the major version of the class file.
88 */
89 public JavaVersion javaVersion() {
90 int javaVer = major - 44;
91 String javaVersion = javaVer < 9 ? "1." + javaVer : Integer.toString(javaVer);
92
93 return JavaVersion.parse(javaVersion);
94 }
95
96 /**
97 * Returns the major version of the parsed classfile.
98 *
99 * @return the major classfile version
100 */
101 public int majorVersion() {
102 return major;
103 }
104
105 /**
106 * Returns the minor version of the parsed classfile.
107 *
108 * @return the minor classfile version
109 */
110 public int minorVersion() {
111 return minor;
112 }
113
114 /**
115 * Returns if the classfile use preview features.
116 *
117 * @return {@code true} if the classfile use preview features.
118 */
119 public boolean isPreview() {
120 return minor == 65535;
121 }
122
123 /**
124 * Returns a String representation of the Java class file version, e.g.
125 * {@code 65.0 (Java 21)}.
126 *
127 * @return String representation of the Java class file version
128 */
129 @Override
130 public String toString() {
131 return major + "." + minor + " (Java " + javaVersion() + ")";
132 }
133
134 @Override
135 public int hashCode() {
136 final int prime = 31;
137 int result = 1;
138 result = prime * result + major;
139 result = prime * result + minor;
140 return result;
141 }
142
143 @Override
144 public boolean equals(Object obj) {
145 if (this == obj) return true;
146 if (!(obj instanceof JavaClassfileVersion)) return false;
147 JavaClassfileVersion other = (JavaClassfileVersion) obj;
148 if (major != other.major) return false;
149 if (minor != other.minor) return false;
150 return true;
151 }
152 }