Example usage for javax.tools SimpleJavaFileObject SimpleJavaFileObject

Introduction

In this page you can find the example usage for javax.tools SimpleJavaFileObject SimpleJavaFileObject.

Prototype

protected SimpleJavaFileObject(URI uri, Kind kind) 

Source Link

Document

Construct a SimpleJavaFileObject of the given kind and with the given URI.

Usage

From source file:org.apache.struts2.JSPLoader.java

/**
 * Compiles the given source code into java bytecode
 *///ww w .j a va2 s . c o  m
private void compileJava(String className, final String source, Set<String> extraClassPath) throws IOException {
    if (LOG.isTraceEnabled())
        LOG.trace("Compiling [#0], source: [#1]", className, source);

    JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();

    DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<JavaFileObject>();

    //the generated bytecode is fed to the class loader
    JavaFileManager jfm = new ForwardingJavaFileManager<StandardJavaFileManager>(
            compiler.getStandardFileManager(diagnostics, null, null)) {

        @Override
        public JavaFileObject getJavaFileForOutput(Location location, String name, JavaFileObject.Kind kind,
                FileObject sibling) throws IOException {
            MemoryJavaFileObject fileObject = new MemoryJavaFileObject(name, kind);
            classLoader.addMemoryJavaFileObject(name, fileObject);
            return fileObject;
        }
    };

    //read java source code from memory
    String fileName = className.replace('.', '/') + ".java";
    SimpleJavaFileObject sourceCodeObject = new SimpleJavaFileObject(toURI(fileName),
            JavaFileObject.Kind.SOURCE) {
        @Override
        public CharSequence getCharContent(boolean ignoreEncodingErrors)
                throws IOException, IllegalStateException, UnsupportedOperationException {
            return source;
        }

    };

    //build classpath
    //some entries will be added multiple times, hence the set
    List<String> optionList = new ArrayList<String>();
    Set<String> classPath = new HashSet<String>();

    FileManager fileManager = ServletActionContext.getContext().getInstance(FileManagerFactory.class)
            .getFileManager();

    //find available jars
    ClassLoaderInterface classLoaderInterface = getClassLoaderInterface();
    UrlSet urlSet = new UrlSet(classLoaderInterface);

    //find jars
    List<URL> urls = urlSet.getUrls();

    for (URL url : urls) {
        URL normalizedUrl = fileManager.normalizeToFileProtocol(url);
        File file = FileUtils.toFile(ObjectUtils.defaultIfNull(normalizedUrl, url));
        if (file.exists())
            classPath.add(file.getAbsolutePath());
    }

    //these should be in the list already, but I am feeling paranoid
    //this jar
    classPath.add(getJarUrl(EmbeddedJSPResult.class));
    //servlet api
    classPath.add(getJarUrl(Servlet.class));
    //jsp api
    classPath.add(getJarUrl(JspPage.class));

    try {
        Class annotationsProcessor = Class.forName("org.apache.AnnotationProcessor");
        classPath.add(getJarUrl(annotationsProcessor));
    } catch (ClassNotFoundException e) {
        //ok ignore
    }

    //add extra classpath entries (jars where tlds were found will be here)
    for (Iterator<String> iterator = extraClassPath.iterator(); iterator.hasNext();) {
        String entry = iterator.next();
        classPath.add(entry);
    }

    String classPathString = StringUtils.join(classPath, File.pathSeparator);
    if (LOG.isDebugEnabled()) {
        LOG.debug("Compiling [#0] with classpath [#1]", className, classPathString);
    }

    optionList.addAll(Arrays.asList("-classpath", classPathString));

    //compile
    JavaCompiler.CompilationTask task = compiler.getTask(null, jfm, diagnostics, optionList, null,
            Arrays.asList(sourceCodeObject));

    if (!task.call()) {
        throw new StrutsException("Compilation failed:" + diagnostics.getDiagnostics().get(0).toString());
    }
}

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