Add constants for modes of generated keys' gathering

h2/src/main/org/h2/command/CommandRemote.java

@@ -9,6 +9,7 @@ import java.io.IOException;
 import java.util.ArrayList;
 
 import org.h2.engine.Constants;
+import org.h2.engine.GeneratedKeysMode;
 import org.h2.engine.SessionRemote;
 import org.h2.engine.SysProperties;
 import org.h2.expression.ParameterInterface;
@@ -212,28 +213,28 @@ public class CommandRemote implements CommandInterface {
                     transfer.writeInt(SessionRemote.COMMAND_EXECUTE_UPDATE).writeInt(id);
                     sendParameters(transfer);
                     if (supportsGeneratedKeys) {
-                        if (Boolean.FALSE.equals(generatedKeysRequest)) {
-                            transfer.writeInt(0);
+                        int mode = GeneratedKeysMode.valueOf(generatedKeysRequest);
+                        transfer.writeInt(mode);
+                        switch (mode) {
+                        case GeneratedKeysMode.NONE:
                             readGeneratedKeys = false;
-                        } else if (Boolean.TRUE.equals(generatedKeysRequest)) {
-                            transfer.writeInt(1);
-                        } else if (generatedKeysRequest instanceof int[]) {
+                            break;
+                        case GeneratedKeysMode.COLUMN_NUMBERS: {
                             int[] keys = (int[]) generatedKeysRequest;
-                            transfer.writeInt(2);
                             transfer.writeInt(keys.length);
                             for (int key : keys) {
                                 transfer.writeInt(key);
                             }
-                        } else if (generatedKeysRequest instanceof String[]) {
+                            break;
+                        }
+                        case GeneratedKeysMode.COLUMN_NAMES: {
                             String[] keys = (String[]) generatedKeysRequest;
-                            transfer.writeInt(3);
                             transfer.writeInt(keys.length);
                             for (String key : keys) {
                                 transfer.writeString(key);
                             }
-                        } else {
-                            transfer.writeInt(0);
-                            readGeneratedKeys = false;
+                            break;
+                        }
                         }
                     }
                     session.done(transfer);

h2/src/main/org/h2/engine/GeneratedKeysMode.java

+/*
+ * Copyright 2004-2018 H2 Group. Multiple-Licensed under the MPL 2.0,
+ * and the EPL 1.0 (http://h2database.com/html/license.html).
+ * Initial Developer: H2 Group
+ */
+package org.h2.engine;
+
+/**
+ * Modes of generated keys' gathering.
+ */
+public final class GeneratedKeysMode {
+
+    /**
+     * Generated keys are not needed.
+     */
+    public static final int NONE = 0;
+
+    /**
+     * Generated keys should be configured automatically.
+     */
+    public static final int AUTO = 1;
+
+    /**
+     * Use specified column indices to return generated keys from.
+     */
+    public static final int COLUMN_NUMBERS = 2;
+
+    /**
+     * Use specified column names to return generated keys from.
+     */
+    public static final int COLUMN_NAMES = 3;
+
+    /**
+     * Determines mode of generated keys' gathering.
+     *
+     * @param generatedKeysRequest
+     *            {@code false} if generated keys are not needed, {@code true} if
+     *            generated keys should be configured automatically, {@code int[]}
+     *            to specify column indices to return generated keys from, or
+     *            {@code String[]} to specify column names to return generated keys
+     *            from
+     * @return mode for the specified generated keys request
+     */
+    public static int valueOf(Object generatedKeysRequest) {
+        if (Boolean.FALSE.equals(generatedKeysRequest)) {
+            return NONE;
+        }
+        if (Boolean.TRUE.equals(generatedKeysRequest)) {
+            return AUTO;
+        }
+        if (generatedKeysRequest instanceof int[]) {
+            return COLUMN_NUMBERS;
+        }
+        if (generatedKeysRequest instanceof String[]) {
+            return COLUMN_NAMES;
+        }
+        return NONE;
+    }
+
+    private GeneratedKeysMode() {
+    }
+
+}

h2/src/main/org/h2/server/TcpServerThread.java

@@ -21,6 +21,7 @@ import org.h2.command.Command;
 import org.h2.engine.ConnectionInfo;
 import org.h2.engine.Constants;
 import org.h2.engine.Engine;
+import org.h2.engine.GeneratedKeysMode;
 import org.h2.engine.Session;
 import org.h2.engine.SessionRemote;
 import org.h2.engine.SysProperties;
@@ -358,16 +359,16 @@ public class TcpServerThread implements Runnable {
             boolean writeGeneratedKeys = supportsGeneratedKeys;
             Object generatedKeysRequest;
             if (supportsGeneratedKeys) {
-                int type = transfer.readInt();
-                switch (type) {
-                default:
+                int mode = transfer.readInt();
+                switch (mode) {
+                case GeneratedKeysMode.NONE:
                     generatedKeysRequest = false;
                     writeGeneratedKeys = false;
                     break;
-                case 1:
+                case GeneratedKeysMode.AUTO:
                     generatedKeysRequest = true;
                     break;
-                case 2: {
+                case GeneratedKeysMode.COLUMN_NUMBERS: {
                     int len = transfer.readInt();
                     int[] keys = new int[len];
                     for (int i = 0; i < len; i++) {
@@ -376,14 +377,18 @@ public class TcpServerThread implements Runnable {
                     generatedKeysRequest = keys;
                     break;
                 }
-                case 3: {
+                case GeneratedKeysMode.COLUMN_NAMES: {
                     int len = transfer.readInt();
                     String[] keys = new String[len];
                     for (int i = 0; i < len; i++) {
                         keys[i] = transfer.readString();
                     }
                     generatedKeysRequest = keys;
+                    break;
                 }
+                default:
+                    throw DbException.get(ErrorCode.CONNECTION_BROKEN_1,
+                            "Unsupported generated keys' mode " + mode);
                 }
             } else {
                 generatedKeysRequest = false;