Better handling of ResultHandler generics detection

spring-shell-core/src/main/java/org/springframework/shell/result/AttributedCharSequenceResultHandler.java

@@ -27,10 +27,10 @@ import org.springframework.stereotype.Component;
  * @author Eric Bottard
  */
 @Component
-public class AttributedCharSequenceResultHandler extends TerminalAwareResultHandler implements ResultHandler<AttributedCharSequence> {
+public class AttributedCharSequenceResultHandler extends TerminalAwareResultHandler<AttributedCharSequence> {
 
 	@Override
-	public void handleResult(AttributedCharSequence result) {
+	protected void doHandleResult(AttributedCharSequence result) {
 		terminal.writer().println(result.toAnsi(terminal));
 		terminal.writer().flush();
 	}

spring-shell-core/src/main/java/org/springframework/shell/result/CommandNotFoundResultHandler.java

@@ -31,10 +31,10 @@ import org.springframework.stereotype.Component;
  * @author Eric Bottard
  */
 @Component
-public class CommandNotFoundResultHandler extends TerminalAwareResultHandler implements ResultHandler<CommandNotFound> {
+public class CommandNotFoundResultHandler extends TerminalAwareResultHandler<CommandNotFound> {
 
 	@Override
-	public void handleResult(CommandNotFound result) {
+	protected void doHandleResult(CommandNotFound result) {
 		terminal.writer().println(new AttributedString(result.getMessage(),
 			AttributedStyle.DEFAULT.foreground(AttributedStyle.RED)).toAnsi());
 		terminal.writer().flush();

spring-shell-core/src/main/java/org/springframework/shell/result/TerminalAwareResultHandler.java

@@ -20,17 +20,26 @@ import org.jline.terminal.Terminal;
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.annotation.Lazy;
+import org.springframework.shell.ResultHandler;
 
 /**
  * Base class for ResultHandlers that rely on JLine's {@link Terminal}.
  *
  * @author Eric Bottard
  */
-public abstract  class TerminalAwareResultHandler {
+public abstract  class TerminalAwareResultHandler<T> implements ResultHandler<T> {
 	protected Terminal terminal;
 
 	@Autowired @Lazy
 	public void setTerminal(Terminal terminal) {
 		this.terminal = terminal;
 	}
+
+	@Override
+	public final void handleResult(T result) {
+		doHandleResult(result);
+		terminal.writer().flush();
+	}
+
+	protected abstract void doHandleResult(T result);
 }

spring-shell-core/src/main/java/org/springframework/shell/result/TerminalSizeAwareResultHandler.java

@@ -24,13 +24,12 @@ import org.springframework.shell.TerminalSizeAware;
  *
  * @author Eric Bottard
  */
-public class TerminalSizeAwareResultHandler extends TerminalAwareResultHandler implements ResultHandler<TerminalSizeAware> {
+public class TerminalSizeAwareResultHandler extends TerminalAwareResultHandler<TerminalSizeAware> {
 
 
 	@Override
-	public void handleResult(TerminalSizeAware result) {
+	protected void doHandleResult(TerminalSizeAware result) {
 		CharSequence toPrint = result.render(terminal.getWidth());
 		terminal.writer().println(toPrint);
-		terminal.writer().flush();
 	}
 }

spring-shell-core/src/main/java/org/springframework/shell/result/ThrowableResultHandler.java

@@ -32,7 +32,7 @@ import org.springframework.stereotype.Component;
  * @author Eric Bottard
  */
 @Component
-public class ThrowableResultHandler extends TerminalAwareResultHandler implements ResultHandler<Throwable> {
+public class ThrowableResultHandler extends TerminalAwareResultHandler<Throwable> {
 
 	/**
 	 * The name of the command that may be used to print details about the last error.
@@ -45,7 +45,7 @@ public class ThrowableResultHandler extends TerminalAwareResultHandler implement
 	private CommandRegistry commandRegistry;
 
 	@Override
-	public void handleResult(Throwable result) {
+	protected void doHandleResult(Throwable result) {
 		lastError = result;
 		terminal.writer().println(new AttributedString(result.toString(),
 				AttributedStyle.DEFAULT.foreground(AttributedStyle.RED)).toAnsi());

spring-shell-core/src/main/java/org/springframework/shell/result/TypeHierarchyResultHandler.java

@@ -23,6 +23,7 @@ import java.util.Map;
 import java.util.Set;
 
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.core.ResolvableType;
 import org.springframework.shell.ResultHandler;
 
 /**
@@ -68,8 +69,8 @@ public class TypeHierarchyResultHandler implements ResultHandler<Object> {
 	@Autowired
 	public void setResultHandlers(Set<ResultHandler<?>> resultHandlers) {
 		for (ResultHandler<?> resultHandler : resultHandlers) {
-			Type type = ((ParameterizedType) resultHandler.getClass().getGenericInterfaces()[0]).getActualTypeArguments()[0];
-			registerHandler((Class<?>) type, resultHandler);
+			ResolvableType type = ResolvableType.forInstance(resultHandler).as(ResultHandler.class);
+			registerHandler(type.resolveGeneric(0), resultHandler);
 		}
 	}