Eclipse comes with its own Java compiler. You can use this compiler to generate an AST from Java code by adding plugins/org.eclipse.jdt.core_<version>.jar to the classpath (details):
import java.io.*;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;
import org.apache.log4j.Logger;
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jdt.core.dom.AST;
import org.eclipse.jdt.core.dom.ASTParser;
import org.eclipse.jdt.core.dom.CompilationUnit;
public class EclipseAstParser {
public static final String VERSION_1_4 = "1.4";
public static final String VERSION_1_5 = "1.5";
public static final String VERSION_1_6 = "1.6";
private static final Set<String> ALLOWED_TARGET_JDKS = new LinkedHashSet<String>();
static {
ALLOWED_TARGET_JDKS.add(VERSION_1_4);
ALLOWED_TARGET_JDKS.add(VERSION_1_5);
ALLOWED_TARGET_JDKS.add(VERSION_1_6);
}
private static final Logger log = Logger.getLogger(EclipseAstParser.class);
public static boolean DEBUG;
private String targetJdk = VERSION_1_4;
private String encoding = "UTF-8";
public void setTargetJdk( String targetJdk ) {
if(!ALLOWED_TARGET_JDKS.contains(targetJdk))
throw new IllegalArgumentException("Invalid value for targetJdk: [" + targetJdk + "]. Allowed are "+ALLOWED_TARGET_JDKS);
this.targetJdk = targetJdk;
}
public void setEncoding( String encoding ) {
if( encoding == null )
throw new IllegalArgumentException("encoding is null");
if( encoding.trim().length() == 0 )
throw new IllegalArgumentException("encoding is empty");
this.encoding = encoding;
}
public AstVisitor visitFile( File file ) throws IOException {
if(!file.exists())
new IllegalArgumentException("File "+file.getAbsolutePath()+" doesn't exist");
String source = readFileToString( file, encoding );
return visitString( source );
}
public static String readFileToString( File file, String encoding ) throws IOException {
FileInputStream stream = new FileInputStream( file );
String result = null;
try {
result = readInputStreamToString( stream, encoding );
} finally {
try {
stream.close();
} catch (IOException e) {
// ignore
}
}
return result;
}
public AstVisitor visit( InputStream stream, String encoding ) throws IOException {
if( stream == null )
throw new IllegalArgumentException("stream is null");
if( encoding == null )
throw new IllegalArgumentException("encoding is null");
if( encoding.trim().length() == 0 )
throw new IllegalArgumentException("encoding is empty");
String source = readInputStreamToString( stream, encoding );
return visitString( source );
}
public static String readInputStreamToString( InputStream stream, String encoding ) throws IOException {
Reader r = new BufferedReader( new InputStreamReader( stream, encoding ), 16384 );
StringBuilder result = new StringBuilder(16384);
char[] buffer = new char[16384];
int len;
while((len = r.read( buffer, 0, buffer.length )) >= 0) {
result.append(buffer, 0, len);
}
return result.toString();
}
public AstVisitor visitString( String source ) {
ASTParser parser = ASTParser.newParser(AST.JLS3);
@SuppressWarnings( "unchecked" )
Map<String,String> options = JavaCore.getOptions();
if(VERSION_1_5.equals(targetJdk))
JavaCore.setComplianceOptions(JavaCore.VERSION_1_5, options);
else if(VERSION_1_6.equals(targetJdk))
JavaCore.setComplianceOptions(JavaCore.VERSION_1_6, options);
else {
if(!VERSION_1_4.equals(targetJdk)) {
log.warn("Unknown targetJdk ["+targetJdk+"]. Using "+VERSION_1_4+" for parsing. Supported values are: "
+ VERSION_1_4 + ", "
+ VERSION_1_5 + ", "
+ VERSION_1_6
);
}
JavaCore.setComplianceOptions(JavaCore.VERSION_1_4, options);
}
parser.setCompilerOptions(options);
parser.setResolveBindings(false);
parser.setStatementsRecovery(false);
parser.setBindingsRecovery(false);
parser.setSource(source.toCharArray());
parser.setIgnoreMethodBodies(false);
CompilationUnit ast = (CompilationUnit) parser.createAST(null);
// AstVisitor extends org.eclipse.jdt.core.dom.ASTVisitor
AstVisitor visitor = new AstVisitor();
visitor.DEBUG = DEBUG;
ast.accept( visitor );
return visitor;
}
}
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