remove fastjson dependency

src/main/java/com/alibaba/druid/stat/DruidDataSourceStatManager.java

@@ -207,6 +207,7 @@ public class DruidDataSourceStatManager implements DruidDataSourceStatManagerMBe
 
     @SuppressWarnings("unchecked")
     public static Set<DruidDataSource> getDruidDataSourceInstances() {
+        getInstances();
         return dataSources.keySet();
     }
 

src/main/java/com/alibaba/druid/support/json/JSONWriter.java

@@ -5,6 +5,9 @@ import java.util.Collection;
 import java.util.Date;
 import java.util.Map;
 
+import javax.management.openmbean.CompositeData;
+import javax.management.openmbean.TabularData;
+
 import com.alibaba.druid.util.IOUtils;
 
 public class JSONWriter {
@@ -24,16 +27,6 @@ public class JSONWriter {
             return;
         }
 
-        if (o instanceof Map) {
-            writeMap((Map) o);
-            return;
-        }
-
-        if (o instanceof Collection) {
-            writeArray((Collection) o);
-            return;
-        }
-
         if (o instanceof String) {
             writeString((String) o);
             return;
@@ -54,6 +47,11 @@ public class JSONWriter {
             return;
         }
 
+        if (o instanceof Collection) {
+            writeArray((Collection) o);
+            return;
+        }
+
         if (o instanceof Throwable) {
             writeError((Throwable) o);
             return;
@@ -85,6 +83,21 @@ public class JSONWriter {
             return;
         }
 
+        if (o instanceof TabularData) {
+            writeTabularData((TabularData) o);
+            return;
+        }
+        
+        if (o instanceof CompositeData) {
+            writeCompositeData((CompositeData) o);
+            return;
+        }
+        
+        if (o instanceof Map) {
+            writeMap((Map) o);
+            return;
+        }
+
         throw new IllegalArgumentException("not support type : " + o.getClass());
     }
 
@@ -169,6 +182,50 @@ public class JSONWriter {
         write('"');
     }
 
+    public void writeTabularData(TabularData tabularData) {
+        if (tabularData == null) {
+            write("null");
+            return;
+        }
+
+        int entryIndex = 0;
+        write('[');
+
+        for (Object item : tabularData.values()) {
+            if (entryIndex != 0) {
+                write(',');
+            }
+            CompositeData row = (CompositeData) item;
+            writeCompositeData(row);
+
+            entryIndex++;
+        }
+        write(']');
+    }
+
+    public void writeCompositeData(CompositeData compositeData) {
+        if (compositeData == null) {
+            write("null");
+            return;
+        }
+
+        int entryIndex = 0;
+        write('{');
+
+        for (Object key : compositeData.getCompositeType().keySet()) {
+            if (entryIndex != 0) {
+                write(',');
+            }
+            writeString((String) key);
+            write(':');
+            Object value = compositeData.get((String) key);
+            writeObject(value);
+            entryIndex++;
+        }
+
+        write('}');
+    }
+
     public void writeMap(Map<String, Object> map) {
         if (map == null) {
             write("null");