changeset 15793:d238b1447080

8159855: Create an SPI for tools Reviewed-by: mchung
author jjg
date Fri, 07 Oct 2016 16:49:31 -0700
parents 1f044f413e6c
children 4251b451be17
files src/java.base/share/classes/java/util/spi/ToolProvider.java src/java.base/share/classes/module-info.java test/java/util/spi/ToolProviderTest.java
diffstat 3 files changed, 271 insertions(+), 0 deletions(-) [+]
line wrap: on
line diff
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.base/share/classes/java/util/spi/ToolProvider.java	Fri Oct 07 16:49:31 2016 -0700
@@ -0,0 +1,165 @@
+/*
+ * Copyright (c) 2016, 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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 java.util.spi;
+
+import java.io.PrintStream;
+import java.io.PrintWriter;
+import java.security.AccessController;
+import java.security.PrivilegedAction;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.ServiceLoader;
+import java.util.stream.StreamSupport;
+
+/**
+ * An interface for command-line tools to provide a way to
+ * be invoked without necessarily starting a new VM.
+ *
+ * <p>Tool providers are normally located using the service-provider
+ * loading facility defined by {@link ServiceLoader}.
+ * Each provider must provide a name, and a method to run
+ * an instance of the corresponding tool. When a tool is run,
+ * it will be provided with an array of string arguments, and a
+ * pair of streams: one for normal (or expected) output and the other
+ * for reporting any errors that may occur.
+ * The interpretation of the string arguments will normally be defined by
+ * each individual tool provider, but will generally correspond to the
+ * arguments that could be provided to the tool when invoking the tool
+ * from the command line.
+ *
+ * @since 9
+ */
+public interface ToolProvider {
+    /**
+     * Returns the name of this tool provider.
+     *
+     * @apiNote It is recommended that the name be the same as would be used on
+     *      the command line: for example, "javac", "jar", "jlink".
+     *
+     * @return the name of this tool provider
+     */
+    String name();
+
+    /**
+     * Runs an instance of the tool, returning zero for a successful run.
+     * Any non-zero return value indicates a tool-specific error during the
+     * execution.
+     * Two streams should be provided, for "expected" output, and for any
+     * error messages. If it is not necessary to distinguish the output,
+     * the same stream may be used for both.
+     *
+     * @apiNote The interpretation of the arguments will be specific to
+     *      each tool.
+     *
+     * @param out a stream to which "expected" output should be written
+     *
+     * @param err a stream to which any error messages should be written
+     *
+     * @param args the command-line arguments for the tool
+     *
+     * @return the result of executing the tool.
+     *      A return value of 0 means the tool did not encounter any errors;
+     *      any other value indicates that at least one error occurred during
+     *      execution.
+     *
+     * @throws NullPointerException if any of the arguments are {@code null},
+     *      or if there are any {@code null} values in the {@code args} array
+     */
+    int run(PrintWriter out, PrintWriter err, String... args);
+
+    /**
+     * Runs an instance of the tool, returning zero for a successful run.
+     * Any non-zero return value indicates a tool-specific error during the
+     * execution.
+     * Two streams should be provided, for "expected" output, and for any
+     * error messages. If it is not necessary to distinguish the output,
+     * the same stream may be used for both.
+     *
+     * @apiNote The interpretation of the arguments will be specific to
+     *      each tool.
+     *
+     * @implNote This implementation wraps the {@code out} and {@code err}
+     *      streams within {@link PrintWriter}s, and then calls
+     *      {@link run(PrintWriter, PrintWriter, String[])}.
+     *
+     * @param out a stream to which "expected" output should be written
+     *
+     * @param err a stream to which any error messages should be written
+     *
+     * @param args the command-line arguments for the tool
+     *
+     * @return the result of executing the tool.
+     *      A return value of 0 means the tool did not encounter any errors;
+     *      any other value indicates that at least one error occurred during
+     *      execution.
+     *
+     * @throws NullPointerException if any of the arguments are {@code null},
+     *      or if there are any {@code null} values in the {@code args} array
+     */
+    default int run(PrintStream out, PrintStream err, String... args) {
+        Objects.requireNonNull(out);
+        Objects.requireNonNull(err);
+        for (String arg : args) {
+            Objects.requireNonNull(args);
+        }
+
+        PrintWriter outWriter = new PrintWriter(out);
+        PrintWriter errWriter = new PrintWriter(err);
+        try {
+            try {
+                return run(outWriter, errWriter, args);
+            } finally {
+                outWriter.flush();
+            }
+        } finally {
+            errWriter.flush();
+        }
+    }
+
+    /**
+     * Returns the first instance of a {@code ToolProvider} with the given name,
+     * as loaded by {@link ServiceLoader} using the system class loader.
+     *
+     * @param name the name of the desired tool provider
+     *
+     * @return an {@code Optional<ToolProvider>} of the first instance found
+     *
+     * @throws NullPointerException if {@code name} is {@code null}
+     */
+    static Optional<ToolProvider> findFirst(String name) {
+        Objects.requireNonNull(name);
+        ClassLoader systemClassLoader = ClassLoader.getSystemClassLoader();
+        return AccessController.doPrivileged(
+            (PrivilegedAction<Optional<ToolProvider>>) () -> {
+                ServiceLoader<ToolProvider> sl =
+                    ServiceLoader.load(ToolProvider.class, systemClassLoader);
+                return StreamSupport.stream(sl.spliterator(), false)
+                    .filter(p -> p.name().equals(name))
+                    .findFirst();
+            });
+    }
+}
+
--- a/src/java.base/share/classes/module-info.java	Fri Oct 07 12:01:24 2016 -0700
+++ b/src/java.base/share/classes/module-info.java	Fri Oct 07 16:49:31 2016 -0700
@@ -108,6 +108,7 @@
     uses java.util.spi.ResourceBundleControlProvider;
     uses java.util.spi.ResourceBundleProvider;
     uses java.util.spi.TimeZoneNameProvider;
+    uses java.util.spi.ToolProvider;
     uses javax.security.auth.spi.LoginModule;
 
 
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/java/util/spi/ToolProviderTest.java	Fri Oct 07 16:49:31 2016 -0700
@@ -0,0 +1,105 @@
+/*
+ * Copyright (c) 2016, 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.
+ */
+
+/*
+ * @test
+ * @bug 8159855
+ * @summary test ToolProvider SPI
+ * @run main/othervm ToolProviderTest
+ */
+
+import java.io.File;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Arrays;
+import java.util.spi.ToolProvider;
+
+public class ToolProviderTest {
+    public static void main(String... args) throws Exception {
+        ToolProviderTest t = new ToolProviderTest();
+        t.run();
+    }
+
+    void run() throws Exception {
+        initServices();
+
+        System.out.println("test without security manager present:");
+        test();
+
+        System.setSecurityManager(new SecurityManager());
+
+        System.out.println("test with security manager present:");
+        test();
+    }
+
+    private void test() throws Exception {
+        ToolProvider testProvider = ToolProvider.findFirst("test").get();
+        int rc = testProvider.run(System.out, System.err, "hello test");
+        if (rc != 0) {
+            throw new Exception("unexpected exit code: " + rc);
+        }
+    }
+
+    private void initServices() throws IOException {
+        Path testClasses = Paths.get(System.getProperty("test.classes"));
+        Path services = testClasses.resolve(Paths.get("META-INF", "services"));
+        Files.createDirectories(services);
+        Files.write(services.resolve(ToolProvider.class.getName()),
+                Arrays.asList(TestProvider.class.getName()));
+    }
+
+    public static class TestProvider implements ToolProvider {
+        public TestProvider() {
+            checkPrivileges();
+        }
+
+        public String name() {
+            return "test";
+        }
+
+        public int run(PrintWriter out, PrintWriter err, String... args) {
+            out.println("Test: " + Arrays.toString(args));
+            return 0;
+        }
+
+        private void checkPrivileges() {
+            boolean haveSecurityManager = (System.getSecurityManager() != null);
+            try {
+                // validate appropriate privileges by checking access to a
+                // system property
+                System.getProperty("java.home");
+                if (haveSecurityManager) {
+                    throw new Error("exception exception not thrown");
+                }
+            } catch (SecurityException e) {
+                if (!haveSecurityManager) {
+                    throw new Error("unexpected exception: " + e);
+                }
+            }
+        }
+    }
+}
+