support BeforeFilter

src/main/java/com/alibaba/fastjson/JSON.java

@@ -35,6 +35,7 @@ import com.alibaba.fastjson.parser.JSONLexer;
 import com.alibaba.fastjson.parser.JSONToken;
 import com.alibaba.fastjson.parser.ParserConfig;
 import com.alibaba.fastjson.parser.deserializer.FieldDeserializer;
+import com.alibaba.fastjson.serializer.BeforeFilter;
 import com.alibaba.fastjson.serializer.JSONSerializer;
 import com.alibaba.fastjson.serializer.NameFilter;
 import com.alibaba.fastjson.serializer.PropertyFilter;
@@ -441,6 +442,10 @@ public abstract class JSON implements JSONStreamAware, JSONAware {
                 if (filter instanceof PropertyFilter) {
                     serializer.getPropertyFilters().add((PropertyFilter) filter);
                 }
+                
+                if (filter instanceof BeforeFilter) {
+                    serializer.getBeforeFilters().add((BeforeFilter) filter);
+                }
             }
 
             serializer.write(object);

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

@@ -56,7 +56,6 @@ import com.alibaba.fastjson.JSONArray;
 import com.alibaba.fastjson.JSONException;
 import com.alibaba.fastjson.JSONObject;
 import com.alibaba.fastjson.parser.deserializer.ASMJavaBeanDeserializer;
-import com.alibaba.fastjson.parser.deserializer.CollectionDeserializer;
 import com.alibaba.fastjson.parser.deserializer.FieldDeserializer;
 import com.alibaba.fastjson.parser.deserializer.IntegerDeserializer;
 import com.alibaba.fastjson.parser.deserializer.JavaBeanDeserializer;

src/main/java/com/alibaba/fastjson/serializer/ASMSerializerFactory.java

@@ -386,6 +386,8 @@ public class ASMSerializerFactory implements Opcodes {
         }
 
         mw.visitVarInsn(ISTORE, context.var("seperator"));
+        
+        _before(mw, context);
 
         for (int i = 0; i < size; ++i) {
             FieldInfo property = getters.get(i);
@@ -1064,6 +1066,15 @@ public class ASMSerializerFactory implements Opcodes {
 
         _seperator(mw, context);
     }
+    
+    private void _before(MethodVisitor mw, Context context) {
+        mw.visitVarInsn(ALOAD, context.serializer());
+        mw.visitVarInsn(ALOAD, context.obj());
+        mw.visitVarInsn(ILOAD, context.var("seperator"));
+        mw.visitMethodInsn(INVOKESTATIC, getType(FilterUtils.class), "writeBefore",
+                "(Lcom/alibaba/fastjson/serializer/JSONSerializer;Ljava/lang/Object;C)C");
+        mw.visitVarInsn(ISTORE, context.var("seperator"));
+    }
 
     private void _apply(MethodVisitor mw, FieldInfo property, Context context) {
         Class<?> propertyClass = property.getFieldClass();

src/main/java/com/alibaba/fastjson/serializer/BeforeFilter.java

@@ -0,0 +1,29 @@
+package com.alibaba.fastjson.serializer;
+
+public abstract class BeforeFilter implements SerializeFilter {
+
+    private final ThreadLocal<JSONSerializer> serializerLocal = new ThreadLocal<JSONSerializer>();
+    private final ThreadLocal<Character>        commaLocal      = new ThreadLocal<Character>();
+
+    private final static Character            COMMA           = Character.valueOf(',');
+
+    final char writeBefore(JSONSerializer serializer, Object object, char commaFlag) {
+        serializerLocal.set(serializer);
+        commaLocal.set(commaFlag);
+        writeBefore(object);
+        serializerLocal.set(null);
+        return commaLocal.get();
+    }
+
+    public abstract void writeBefore(Object object);
+
+    public final void writeKeyValue(String key, Object value) {
+        JSONSerializer serializer = serializerLocal.get();
+        char comma = commaLocal.get();
+        serializer.writeKeyValue(comma, key, value);
+        if (comma != ',') {
+            commaLocal.set(COMMA);
+        }
+    }
+
+}

src/main/java/com/alibaba/fastjson/serializer/FilterUtils.java

@@ -3,7 +3,17 @@ package com.alibaba.fastjson.serializer;
 import java.util.List;
 
 public class FilterUtils {
+    public static char writeBefore(JSONSerializer serializer, Object object, char seperator) {
+        List<BeforeFilter> beforeFilters = serializer.getBeforeFilters();
+        if (beforeFilters != null) {
+            for (BeforeFilter beforeFilter : beforeFilters) {
+                seperator = beforeFilter.writeBefore(serializer, object, seperator);
+            }
+        }
+        return seperator;
+    }
 
+    
     public static Object processValue(JSONSerializer serializer, Object object, String key, Object propertyValue) {
         List<ValueFilter> valueFilters = serializer.getValueFiltersDirect();
         if (valueFilters != null) {

src/main/java/com/alibaba/fastjson/serializer/JSONSerializer.java

@@ -48,6 +48,7 @@ public class JSONSerializer {
 
     private final SerializeWriter                  out;
 
+    private List<BeforeFilter>                     beforeFilters      = null;
     private List<PropertyFilter>                   propertyFilters    = null;
     private List<ValueFilter>                      valueFilters       = null;
     private List<NameFilter>                       nameFilters        = null;
@@ -251,6 +252,18 @@ public class JSONSerializer {
             out.write(indent);
         }
     }
+    
+    public List<BeforeFilter> getBeforeFilters() {
+        if (beforeFilters == null) {
+            beforeFilters = new ArrayList<BeforeFilter>();
+        }
+
+        return beforeFilters;
+    }
+    
+    public List<BeforeFilter> getBeforeFiltersDirect() {
+        return beforeFilters;
+    }
 
     public List<NameFilter> getNameFilters() {
         if (nameFilters == null) {
@@ -349,6 +362,14 @@ public class JSONSerializer {
     public final void writeWithFieldName(Object object, Object fieldName) {
         writeWithFieldName(object, fieldName, null);
     }
+    
+    protected final void writeKeyValue(char seperator, String key, Object value) {
+        if (seperator != '\0') {
+            out.write(seperator);
+        }
+        out.writeFieldName(key);
+        write(value);
+    }
 
     public final void writeWithFieldName(Object object, Object fieldName, Type fieldType) {
         try {

src/main/java/com/alibaba/fastjson/serializer/JavaBeanSerializer.java

@@ -128,6 +128,11 @@ public class JavaBeanSerializer implements ObjectSerializer {
                     commaFlag = true;
                 }
             }
+            
+            char seperator = commaFlag ? ',':'\0';
+            
+            char newSeperator = FilterUtils.writeBefore(serializer, object, seperator);
+            commaFlag = newSeperator == ',';
 
             for (int i = 0; i < getters.length; ++i) {
                 FieldSerializer fieldSerializer = getters[i];

src/main/java/com/alibaba/fastjson/serializer/MapSerializer.java

@@ -18,7 +18,6 @@ package com.alibaba.fastjson.serializer;
 import java.io.IOException;
 import java.lang.reflect.Type;
 import java.util.LinkedHashMap;
-import java.util.List;
 import java.util.Map;
 import java.util.SortedMap;
 import java.util.TreeMap;

src/test/java/com/alibaba/json/bvt/serializer/BeforeFilterTest.java

@@ -0,0 +1,37 @@
+package com.alibaba.json.bvt.serializer;
+
+import junit.framework.TestCase;
+
+import org.junit.Assert;
+
+import com.alibaba.fastjson.JSON;
+import com.alibaba.fastjson.serializer.BeforeFilter;
+
+public class BeforeFilterTest extends TestCase {
+    public void test_beforeFilter() throws Exception {
+        BeforeFilter filter = new BeforeFilter() {
+            
+            @Override
+            public void writeBefore(Object object) {
+                this.writeKeyValue("id", 123);
+            }
+        };
+        Assert.assertEquals("{\"id\":123}",JSON.toJSONString( new VO(), filter));
+    }
+    
+    public void test_beforeFilter2() throws Exception {
+        BeforeFilter filter = new BeforeFilter() {
+            
+            @Override
+            public void writeBefore(Object object) {
+                this.writeKeyValue("id", 123);
+                this.writeKeyValue("name", "wenshao");
+            }
+        };
+        Assert.assertEquals("{\"id\":123,\"name\":\"wenshao\"}", JSON.toJSONString(new VO(), filter));
+    }
+    
+    private static class VO {
+        
+    }
+}

src/test/java/com/alibaba/json/bvt/serializer/BeforeFilterTest2.java

@@ -0,0 +1,37 @@
+package com.alibaba.json.bvt.serializer;
+
+import junit.framework.TestCase;
+
+import org.junit.Assert;
+
+import com.alibaba.fastjson.JSON;
+import com.alibaba.fastjson.serializer.BeforeFilter;
+
+public class BeforeFilterTest2 extends TestCase {
+    public void test_beforeFilter() throws Exception {
+        BeforeFilter filter = new BeforeFilter() {
+            
+            @Override
+            public void writeBefore(Object object) {
+                this.writeKeyValue("id", 123);
+            }
+        };
+        Assert.assertEquals(JSON.toJSONString(new VO(), filter), "{\"id\":123}");
+    }
+    
+    public void test_beforeFilter2() throws Exception {
+        BeforeFilter filter = new BeforeFilter() {
+            
+            @Override
+            public void writeBefore(Object object) {
+                this.writeKeyValue("id", 123);
+                this.writeKeyValue("name", "wenshao");
+            }
+        };
+        Assert.assertEquals(JSON.toJSONString(new VO(), filter), "{\"id\":123,\"name\":\"wenshao\"}");
+    }
+    
+    public static class VO {
+        
+    }
+}