Create App.java

Chain of Responsibility Pattern in Java: Building Robust Request Handling Mechanisms

localization/zh/chain/App.java

@@ -0,0 +1,93 @@
+@Getter
+public class Request {
+
+    private final RequestType requestType;
+    private final String requestDescription;
+    private boolean handled;
+
+    public Request(final RequestType requestType, final String requestDescription) {
+        this.requestType = Objects.requireNonNull(requestType);
+        this.requestDescription = Objects.requireNonNull(requestDescription);
+    }
+
+    public void markHandled() {
+        this.handled = true;
+    }
+
+    @Override
+    public String toString() {
+        return getRequestDescription();
+    }
+}
+
+public enum RequestType {
+    DEFEND_CASTLE, TORTURE_PRISONER, COLLECT_TAX
+}
+
+public interface RequestHandler {
+
+    boolean canHandleRequest(Request req);
+
+    int getPriority();
+
+    void handle(Request req);
+
+    String name();
+}
+
+@Slf4j
+public class OrcCommander implements RequestHandler {
+    @Override
+    public boolean canHandleRequest(Request req) {
+        return req.getRequestType() == RequestType.DEFEND_CASTLE;
+    }
+
+    @Override
+    public int getPriority() {
+        return 2;
+    }
+
+    @Override
+    public void handle(Request req) {
+        req.markHandled();
+        LOGGER.info("{} handling request \"{}\"", name(), req);
+    }
+
+    @Override
+    public String name() {
+        return "Orc commander";
+    }
+}
+
+// OrcOfficer and OrcSoldier are defined similarly as OrcCommander ...
+
+
+public class OrcKing {
+
+    private List<RequestHandler> handlers;
+
+    public OrcKing() {
+        buildChain();
+    }
+
+    private void buildChain() {
+        handlers = Arrays.asList(new OrcCommander(), new OrcOfficer(), new OrcSoldier());
+    }
+
+    public void makeRequest(Request req) {
+        handlers
+                .stream()
+                .sorted(Comparator.comparing(RequestHandler::getPriority))
+                .filter(handler -> handler.canHandleRequest(req))
+                .findFirst()
+                .ifPresent(handler -> handler.handle(req));
+    }
+}
+
+  public static void main(String[] args) {
+
+    var king = new OrcKing();
+    king.makeRequest(new Request(RequestType.DEFEND_CASTLE, "defend castle"));
+    king.makeRequest(new Request(RequestType.TORTURE_PRISONER, "torture prisoner"));
+    king.makeRequest(new Request(RequestType.COLLECT_TAX, "collect tax"));
+}