improved JSONReader performance, fix #3627

src/main/java/com/alibaba/fastjson/parser/DefaultJSONParser.java

@@ -327,6 +327,8 @@ public final Object parseObject(final Map object, Object fieldName) {
                     if (object != null
                             && object.getClass().getName().equals(typeName)) {
                         clazz = object.getClass();
+                    } else if ("java.util.HashMap".equals(typeName)) {
+                        clazz = java.util.HashMap.class;
                     } else {
 
                         boolean allDigits = true;

src/test/java/com/alibaba/json/bvt/parser/stream/JSONReaderTest_5.java

@@ -0,0 +1,51 @@
+package com.alibaba.json.bvt.parser.stream;
+
+import com.alibaba.fastjson.JSONArray;
+import com.alibaba.fastjson.JSONObject;
+import com.alibaba.fastjson.JSONReader;
+import junit.framework.TestCase;
+import org.junit.Assert;
+
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.StringReader;
+import java.util.HashMap;
+import java.util.Map;
+
+public class JSONReaderTest_5 extends TestCase {
+	public void test_read() throws Exception {
+		final int COUNT = 1000 * 10;
+		StringBuilder buf = new StringBuilder();
+		buf.append('[');
+		for (int i = 0; i < COUNT; ++i) {
+			if (i != 0) {
+				buf.append(',');
+			}
+			buf.append("{\"id\":").append(i).append('}');
+		}
+		buf.append(']');
+
+
+		JSONReader reader = new JSONReader(new StringReader(buf.toString()));
+
+		reader.startArray();
+		Map map = new HashMap();
+		int count = 0;
+		for (;;) {
+			if (reader.hasNext()) {
+				reader.startObject();
+				String key = reader.readString();
+				Long value = reader.readLong();
+				reader.endObject();
+				count++;
+			} else {
+				break;
+			}
+		}
+		assertEquals(COUNT, count);
+
+		reader.endArray();
+
+		reader.close();
+	}
+}