fixed JSON datatype string parse

dbsync/src/main/java/com/taobao/tddl/dbsync/binlog/JsonConversion.java

@@ -158,7 +158,7 @@ public class JsonConversion {
                     throw new IllegalArgumentException("illegal json data");
                 }
                 return new Json_Value(Json_enum_type.STRING,
-                    buffer.rewind().forward((int) n).getFixStringIgnore0000((int) str_len, charset));
+                    buffer.rewind().forward((int) n).getFixLengthString((int) str_len, charset));
             case JSONB_TYPE_OPAQUE:
                 /*
                  * There should always be at least one byte, which tells the field type of the
@@ -257,7 +257,7 @@ public class JsonConversion {
             // entry, always two
             // bytes.
             long key_length = m_data.getUint16();
-            return m_data.rewind().forward((int) key_offset).getFixStringIgnore0000((int) key_length, charset);
+            return m_data.rewind().forward((int) key_offset).getFixLengthString((int) key_length, charset);
         }
 
         public Json_Value element(int i, Charset charset) {
@@ -400,7 +400,7 @@ public class JsonConversion {
                                    }
                                    buf.append('"').append(text).append('"');
                                } else {
-                                   text = m_data.getFixStringIgnore0000((int) m_length, charset);
+                                   text = m_data.getFixLengthString((int) m_length, charset);
                                    buf.append('"').append(escapse(text)).append('"');
                                }
 

dbsync/src/main/java/com/taobao/tddl/dbsync/binlog/LogBuffer.java

@@ -1157,9 +1157,10 @@ public class LogBuffer {
     }
 
     /**
-     * Return next fix length string from buffer. ignore \0
+     * Return next fix length string from buffer.
+     * see json_binary.cc read_variable_length
      */
-    public final String getFixStringIgnore0000(final int len, Charset charset) {
+    public final String getFixLengthString(final int len, Charset charset) {
         if (position + len > origin + limit) {
             throw new IllegalArgumentException("limit excceed: " + (position + len - origin));
         }