diff --git a/src/main/java/com/alibaba/druid/filter/stat/StatFilter.java b/src/main/java/com/alibaba/druid/filter/stat/StatFilter.java
index facb4864bc..7af7ba5012 100644
--- a/src/main/java/com/alibaba/druid/filter/stat/StatFilter.java
+++ b/src/main/java/com/alibaba/druid/filter/stat/StatFilter.java
@@ -24,7 +24,6 @@ import java.sql.SQLException;
 import java.sql.Savepoint;
 import java.util.Date;
 import java.util.Properties;
-import java.util.concurrent.atomic.AtomicLong;
 
 import com.alibaba.druid.filter.Filter;
 import com.alibaba.druid.filter.FilterChain;
@@ -79,8 +78,6 @@ public class StatFilter extends FilterEventAdapter implements StatFilterMBean {
 
     private boolean                   connectionStackTraceEnable = false;
 
-    protected final AtomicLong        resetCount                 = new AtomicLong();
-
     // 3 seconds is slow sql
     protected long                    slowSqlMillis              = 3 * 1000;
 
@@ -113,10 +110,6 @@ public class StatFilter extends FilterEventAdapter implements StatFilterMBean {
         this.connectionStackTraceEnable = connectionStackTraceEnable;
     }
 
-    public long getResetCount() {
-        return resetCount.get();
-    }
-
     public boolean isMergeSql() {
         return mergeSql;
     }
@@ -837,9 +830,7 @@ public class StatFilter extends FilterEventAdapter implements StatFilterMBean {
 
         if (obj instanceof Clob) {
             clobOpenAfter(chain.getDataSource().getDataSourceStat(), statement, (ClobProxy) obj);
-        }
-
-        if (obj instanceof Blob) {
+        } else if (obj instanceof Blob) {
             blobOpenAfter(chain.getDataSource().getDataSourceStat(), statement, (Blob) obj);
         }
 
@@ -853,9 +844,7 @@ public class StatFilter extends FilterEventAdapter implements StatFilterMBean {
 
         if (obj instanceof Clob) {
             clobOpenAfter(chain.getDataSource().getDataSourceStat(), statement, (ClobProxy) obj);
-        }
-
-        if (obj instanceof Blob) {
+        } else if (obj instanceof Blob) {
             blobOpenAfter(chain.getDataSource().getDataSourceStat(), statement, (Blob) obj);
         }
 
@@ -869,9 +858,7 @@ public class StatFilter extends FilterEventAdapter implements StatFilterMBean {
 
         if (obj instanceof Clob) {
             clobOpenAfter(chain.getDataSource().getDataSourceStat(), statement, (ClobProxy) obj);
-        }
-
-        if (obj instanceof Blob) {
+        } else if (obj instanceof Blob) {
             blobOpenAfter(chain.getDataSource().getDataSourceStat(), statement, (Blob) obj);
         }
 
@@ -886,9 +873,7 @@ public class StatFilter extends FilterEventAdapter implements StatFilterMBean {
 
         if (obj instanceof Clob) {
             clobOpenAfter(chain.getDataSource().getDataSourceStat(), statement, (ClobProxy) obj);
-        }
-
-        if (obj instanceof Blob) {
+        } else if (obj instanceof Blob) {
             blobOpenAfter(chain.getDataSource().getDataSourceStat(), statement, (Blob) obj);
         }
 
diff --git a/src/test/java/com/alibaba/druid/bvt/filter/FilterManagerTest.java b/src/test/java/com/alibaba/druid/bvt/filter/FilterManagerTest.java
new file mode 100644
index 0000000000..9f20f2ad01
--- /dev/null
+++ b/src/test/java/com/alibaba/druid/bvt/filter/FilterManagerTest.java
@@ -0,0 +1,48 @@
+package com.alibaba.druid.bvt.filter;
+
+import java.sql.SQLException;
+import java.util.ArrayList;
+
+import junit.framework.TestCase;
+
+import org.junit.Assert;
+
+import com.alibaba.druid.filter.Filter;
+import com.alibaba.druid.filter.FilterAdapter;
+import com.alibaba.druid.filter.FilterManager;
+
+public class FilterManagerTest extends TestCase {
+
+    public void test_instance() throws Exception {
+        new FilterManager();
+    }
+
+    public void test_loadFilter() throws Exception {
+        Exception error = null;
+
+        try {
+            FilterManager.loadFilter(new ArrayList<Filter>(), ErrorFilter.class.getName());
+        } catch (SQLException e) {
+            error = e;
+        }
+        Assert.assertNotNull(error);
+    }
+    
+    public void test_loadFilter_2() throws Exception {
+        Exception error = null;
+        
+        try {
+            FilterManager.loadFilter(new ArrayList<Filter>(), ErrorFilter.class.getName());
+        } catch (SQLException e) {
+            error = e;
+        }
+        Assert.assertNotNull(error);
+    }
+
+    public static class ErrorFilter extends FilterAdapter {
+
+        public ErrorFilter(){
+            throw new RuntimeException();
+        }
+    }
+}
diff --git a/src/test/java/com/alibaba/druid/bvt/proxy/filter/StatFilterTest3.java b/src/test/java/com/alibaba/druid/bvt/proxy/filter/StatFilterTest3.java
new file mode 100644
index 0000000000..5f9c636f58
--- /dev/null
+++ b/src/test/java/com/alibaba/druid/bvt/proxy/filter/StatFilterTest3.java
@@ -0,0 +1,43 @@
+package com.alibaba.druid.bvt.proxy.filter;
+
+import junit.framework.Assert;
+import junit.framework.TestCase;
+
+import com.alibaba.druid.filter.stat.StatFilter;
+
+public class StatFilterTest3 extends TestCase {
+    public void test_dbType() throws Exception {
+        StatFilter filter = new StatFilter();
+        
+        Assert.assertFalse(filter.isMergeSql());
+        
+        filter.setDbType("mysql");
+        filter.setMergeSql(true);
+        
+        Assert.assertTrue(filter.isMergeSql());
+        Assert.assertEquals("mysql", filter.getDbType());
+        
+        Assert.assertEquals("SELECT ?\nLIMIT ?" , filter.mergeSql("select 'x' limit 1"));
+    }
+    
+    public void test_dbType_error() throws Exception {
+        StatFilter filter = new StatFilter();
+        filter.setDbType("mysql");
+        filter.setMergeSql(true);
+        
+        Assert.assertEquals("mysql", filter.getDbType());
+        
+        Assert.assertEquals("sdafawer asf " , filter.mergeSql("sdafawer asf "));
+    }
+    
+    public void test_merge() throws Exception {
+        StatFilter filter = new StatFilter();
+        filter.setDbType("mysql");
+        filter.setMergeSql(false);
+        
+        Assert.assertEquals("mysql", filter.getDbType());
+        
+        Assert.assertEquals("select 'x' limit 1" , filter.mergeSql("select 'x' limit 1"));
+    }
+    
+}