1 |
|
---|
2 | package de.ugoe.cs.eventbench.jfcmonitor;
|
---|
3 |
|
---|
4 | import java.io.FileInputStream;
|
---|
5 | import java.io.FileNotFoundException;
|
---|
6 | import java.io.IOException;
|
---|
7 | import java.lang.reflect.InvocationTargetException;
|
---|
8 | import java.lang.reflect.Method;
|
---|
9 | import java.net.MalformedURLException;
|
---|
10 | import java.net.URL;
|
---|
11 | import java.net.URLClassLoader;
|
---|
12 | import java.util.Arrays;
|
---|
13 | import java.util.jar.JarInputStream;
|
---|
14 | import java.util.jar.Manifest;
|
---|
15 |
|
---|
16 | /**
|
---|
17 | * <p>
|
---|
18 | * Class that launches an executable Jar-file in the same thread and VM where the JarLauncher
|
---|
19 | * instance is created. The requirements on the Jar file are:
|
---|
20 | * <li>Must contain a MANIFEST.</li>
|
---|
21 | * <li>The MANIFEST must define the main-class of the application ("Main-Class" entry).</li>
|
---|
22 | * <li>The MANIFEST must define the classpath of the application ("Class-Path" entry).</li>
|
---|
23 | * </p>
|
---|
24 | *
|
---|
25 | * @author Steffen Herbold
|
---|
26 | * @version 1.0
|
---|
27 | */
|
---|
28 | public class JarLauncher {
|
---|
29 |
|
---|
30 | /**
|
---|
31 | * <p>
|
---|
32 | * Name of the Jar file to be executed.
|
---|
33 | * </p>
|
---|
34 | */
|
---|
35 | private String jarfile;
|
---|
36 |
|
---|
37 | /**
|
---|
38 | * <p>
|
---|
39 | * Arguments for launching the Jar file.
|
---|
40 | * </p>
|
---|
41 | */
|
---|
42 | private String[] args;
|
---|
43 |
|
---|
44 | /**
|
---|
45 | * <p>
|
---|
46 | * Helper variable with the path to the working directory.
|
---|
47 | * </p>
|
---|
48 | */
|
---|
49 | final String workingDir = System.getProperty("user.dir") + "/";
|
---|
50 |
|
---|
51 | /**
|
---|
52 | * <p>
|
---|
53 | * Internal variable used to store the classpath extracted from the Jar file's MANIFEST.
|
---|
54 | * </p>
|
---|
55 | */
|
---|
56 | private String[] classPath = new String[] { };
|
---|
57 |
|
---|
58 | /**
|
---|
59 | * <p>
|
---|
60 | * Internal variable used to store the name (including package information) of the Jar file's
|
---|
61 | * main function extracted from the Jar file's MANIFEST.
|
---|
62 | * </p>
|
---|
63 | */
|
---|
64 | private String mainClassName = "";
|
---|
65 |
|
---|
66 | /**
|
---|
67 | * <p>
|
---|
68 | * Inner class that defines an exception that is thrown if launching the application in the Jar
|
---|
69 | * file fails.
|
---|
70 | * </p>
|
---|
71 | *
|
---|
72 | * @author Steffen Herbold
|
---|
73 | * @version 1.0
|
---|
74 | */
|
---|
75 | private static class JarLaunchException extends Exception {
|
---|
76 |
|
---|
77 | /**
|
---|
78 | * <p>
|
---|
79 | * Id for object serialization.
|
---|
80 | * </p>
|
---|
81 | */
|
---|
82 | private static final long serialVersionUID = 1L;
|
---|
83 |
|
---|
84 | /**
|
---|
85 | * <p>
|
---|
86 | * Constructor. Creates a new JarLaunchException.
|
---|
87 | * </p>
|
---|
88 | *
|
---|
89 | * @param string
|
---|
90 | * error message of the exception
|
---|
91 | */
|
---|
92 | public JarLaunchException(String string) {
|
---|
93 | super(string);
|
---|
94 | }
|
---|
95 |
|
---|
96 | /**
|
---|
97 | * <p>
|
---|
98 | * Constructor. Creates a new JarLaunchException as a copy of an existing exception.
|
---|
99 | * </p>
|
---|
100 | *
|
---|
101 | * @param e
|
---|
102 | * exception that is copied
|
---|
103 | */
|
---|
104 | public JarLaunchException(Exception e) {
|
---|
105 | super(e);
|
---|
106 | }
|
---|
107 |
|
---|
108 | }
|
---|
109 |
|
---|
110 | /**
|
---|
111 | * <p>
|
---|
112 | * Constructor. Creates a new JarLauncher.
|
---|
113 | * </p>
|
---|
114 | *
|
---|
115 | * @param jarfile
|
---|
116 | * file to be launched; must not be complete path but in relation to the current
|
---|
117 | * working directory
|
---|
118 | * @param args
|
---|
119 | * arguments with which the main function of the Jar file is called
|
---|
120 | */
|
---|
121 | public JarLauncher(String jarfile, String[] args) {
|
---|
122 | this.jarfile = jarfile;
|
---|
123 | this.args = Arrays.copyOf(args, args.length);
|
---|
124 | }
|
---|
125 |
|
---|
126 | /**
|
---|
127 | * <p>
|
---|
128 | * Executes the main function of the Jar file associated with this launcher.
|
---|
129 | * </p>
|
---|
130 | */
|
---|
131 | public void exec() {
|
---|
132 | try {
|
---|
133 | getInfoFromJar();
|
---|
134 | initClassLoader();
|
---|
135 | runMain();
|
---|
136 | }
|
---|
137 | catch (JarLaunchException e) {
|
---|
138 | System.err.println("Failure to launch application.");
|
---|
139 | System.err.println(e.getMessage());
|
---|
140 | }
|
---|
141 | }
|
---|
142 |
|
---|
143 | /**
|
---|
144 | * <p>
|
---|
145 | * Retrieves the classpath and main function from the Jar file's MANIFEST.
|
---|
146 | * </p>
|
---|
147 | *
|
---|
148 | * @throws JarLaunchException
|
---|
149 | * thrown if reading of Jar file or MANIFEST fails
|
---|
150 | */
|
---|
151 | private void getInfoFromJar() throws JarLaunchException {
|
---|
152 | JarInputStream jarInputStream;
|
---|
153 | try {
|
---|
154 | jarInputStream = new JarInputStream(new FileInputStream(workingDir + jarfile));
|
---|
155 | }
|
---|
156 | catch (FileNotFoundException e) {
|
---|
157 | throw new JarLaunchException(e);
|
---|
158 | }
|
---|
159 | catch (IOException e) {
|
---|
160 | throw new JarLaunchException(e);
|
---|
161 | }
|
---|
162 | Manifest manifest = jarInputStream.getManifest();
|
---|
163 | mainClassName = manifest.getMainAttributes().getValue("Main-Class");
|
---|
164 | String jarClassPath = manifest.getMainAttributes().getValue("Class-Path");
|
---|
165 | String[] jarClassPathElements = jarClassPath.split(" ");
|
---|
166 | classPath = new String[jarClassPathElements.length];
|
---|
167 | for (int i = 0; i < jarClassPathElements.length; i++) {
|
---|
168 | classPath[i] = "file:" + workingDir + jarClassPathElements[i];
|
---|
169 | }
|
---|
170 | try {
|
---|
171 | jarInputStream.close();
|
---|
172 | }
|
---|
173 | catch (IOException e) {
|
---|
174 | e.printStackTrace();
|
---|
175 | }
|
---|
176 | }
|
---|
177 |
|
---|
178 | /**
|
---|
179 | * <p>
|
---|
180 | * Modifies the {@link ClassLoader} of the current VM such that it includes the class path
|
---|
181 | * defined in the Jar file's MANIFEST.
|
---|
182 | * </p>
|
---|
183 | *
|
---|
184 | * @throws JarLaunchException
|
---|
185 | * thrown if modification of {@link ClassLoader} fails.
|
---|
186 | */
|
---|
187 | private void initClassLoader() throws JarLaunchException {
|
---|
188 | URLClassLoader classLoader = (URLClassLoader) ClassLoader.getSystemClassLoader();
|
---|
189 | Method method;
|
---|
190 | try {
|
---|
191 | method = URLClassLoader.class.getDeclaredMethod("addURL", new Class[]
|
---|
192 | { URL.class });
|
---|
193 | }
|
---|
194 | catch (SecurityException e) {
|
---|
195 | throw new JarLaunchException(
|
---|
196 | "addURL method of URLClassLoader not accessible via reflection.");
|
---|
197 | }
|
---|
198 | catch (NoSuchMethodException e) {
|
---|
199 | throw new JarLaunchException(
|
---|
200 | "URLClassLoader does not have addURL method. Should be impossible!!");
|
---|
201 | }
|
---|
202 | method.setAccessible(true);
|
---|
203 |
|
---|
204 | try {
|
---|
205 | method.invoke(classLoader, new Object[]
|
---|
206 | { new URL("file:" + workingDir + jarfile) });
|
---|
207 | for (String element : classPath) {
|
---|
208 | method.invoke(classLoader, new Object[]
|
---|
209 | { new URL(element) });
|
---|
210 | }
|
---|
211 | }
|
---|
212 | catch (IllegalArgumentException e) {
|
---|
213 | throw new JarLaunchException(
|
---|
214 | "Illegal arguments for addURL method. Should be impossible!!");
|
---|
215 | }
|
---|
216 | catch (MalformedURLException e) {
|
---|
217 | throw new JarLaunchException(e);
|
---|
218 | }
|
---|
219 | catch (IllegalAccessException e) {
|
---|
220 | throw new JarLaunchException(
|
---|
221 | "addURL method of URLClassLoader not accessible via reflection.");
|
---|
222 | }
|
---|
223 | catch (InvocationTargetException e) {
|
---|
224 | e.printStackTrace();
|
---|
225 | }
|
---|
226 | }
|
---|
227 |
|
---|
228 | /**
|
---|
229 | * <p>
|
---|
230 | * Executes the main function.
|
---|
231 | * </p>
|
---|
232 | *
|
---|
233 | * @throws JarLaunchException
|
---|
234 | * thrown if execution of main function fails or the main function itself throws an
|
---|
235 | * exception
|
---|
236 | */
|
---|
237 | private void runMain() throws JarLaunchException {
|
---|
238 | Class<?> mainClass;
|
---|
239 | try {
|
---|
240 | mainClass = Class.forName(mainClassName);
|
---|
241 | }
|
---|
242 | catch (ClassNotFoundException e) {
|
---|
243 | throw new JarLaunchException("Main class not found: " + mainClassName);
|
---|
244 | }
|
---|
245 | Method mainMethod;
|
---|
246 | try {
|
---|
247 | mainMethod = mainClass.getMethod("main", new Class[]
|
---|
248 | { String[].class });
|
---|
249 | }
|
---|
250 | catch (SecurityException e) {
|
---|
251 | throw new JarLaunchException("Main method not accessible.");
|
---|
252 | }
|
---|
253 | catch (NoSuchMethodException e) {
|
---|
254 | throw new JarLaunchException("Main method not found.");
|
---|
255 | }
|
---|
256 | try {
|
---|
257 | mainMethod.invoke(null, new Object[]
|
---|
258 | { args });
|
---|
259 | }
|
---|
260 | catch (IllegalArgumentException e) {
|
---|
261 | throw new JarLaunchException(
|
---|
262 | "Illegal arguments for main method. Should be impossible!!");
|
---|
263 | }
|
---|
264 | catch (IllegalAccessException e) {
|
---|
265 | throw new JarLaunchException("Main method not accessible.");
|
---|
266 | }
|
---|
267 | catch (InvocationTargetException e) {
|
---|
268 | throw new JarLaunchException(e);
|
---|
269 | }
|
---|
270 | }
|
---|
271 | }
|
---|