fixes #549 Allow referencing statement parameters by their actual names (i.e. the names in the method signature). To use this feature, 1) the project must be compiled in Java 8 with '-parameters' option and 2) 'useActualParamName' must be set to true in MyBatis configuration.

Author: harawata

src/main/java/org/apache/ibatis/binding/MapperMethod.java

@@ -259,7 +259,7 @@ public MethodSignature(Configuration configuration, Class<?> mapperInterface, Me
       this.returnsMap = (this.mapKey != null);
       this.rowBoundsIndex = getUniqueParamIndex(method, RowBounds.class);
       this.resultHandlerIndex = getUniqueParamIndex(method, ResultHandler.class);
-      this.paramNameResolver = new ParamNameResolver(method);
+      this.paramNameResolver = new ParamNameResolver(configuration, method);
     }
 
     public Object convertArgsToSqlCommandParam(Object[] args) {

src/main/java/org/apache/ibatis/builder/annotation/ProviderSqlSource.java

@@ -53,7 +53,7 @@ public ProviderSqlSource(Configuration config, Object provider) {
                       + "'. Sql provider method can not overload.");
             }
             this.providerMethod = m;
-            this.providerMethodArgumentNames = new ParamNameResolver(m).getNames();
+            this.providerMethodArgumentNames = new ParamNameResolver(config, m).getNames();
           }
         }
       }

src/main/java/org/apache/ibatis/builder/xml/XMLConfigBuilder.java

@@ -255,6 +255,7 @@ private void settingsElement(Properties props) throws Exception {
     configuration.setSafeResultHandlerEnabled(booleanValueOf(props.getProperty("safeResultHandlerEnabled"), true));
     configuration.setDefaultScriptingLanguage(resolveClass(props.getProperty("defaultScriptingLanguage")));
     configuration.setCallSettersOnNulls(booleanValueOf(props.getProperty("callSettersOnNulls"), false));
+    configuration.setUseActualParamName(booleanValueOf(props.getProperty("useActualParamName"), false));
     configuration.setLogPrefix(props.getProperty("logPrefix"));
     @SuppressWarnings("unchecked")
     Class<? extends Log> logImpl = (Class<? extends Log>)resolveClass(props.getProperty("logImpl"));

src/main/java/org/apache/ibatis/reflection/ParamNameResolver.java

@@ -25,12 +25,27 @@
 
 import org.apache.ibatis.annotations.Param;
 import org.apache.ibatis.binding.MapperMethod.ParamMap;
+import org.apache.ibatis.io.Resources;
+import org.apache.ibatis.session.Configuration;
 import org.apache.ibatis.session.ResultHandler;
 import org.apache.ibatis.session.RowBounds;
 
 public class ParamNameResolver {
 
   private static final String GENERIC_NAME_PREFIX = "param";
+  private static final String PARAMETER_CLASS = "java.lang.reflect.Parameter";
+  private static Method GET_NAME = null;
+  private static Method GET_PARAMS = null;
+
+  static {
+    try {
+      Class<?> paramClass = Resources.classForName(PARAMETER_CLASS);
+      GET_NAME = paramClass.getMethod("getName");
+      GET_PARAMS = Method.class.getMethod("getParameters");
+    } catch (Exception e) {
+      // ignore
+    }
+  }
 
   /**
    * <p>
@@ -49,7 +64,7 @@ public class ParamNameResolver {
 
   private boolean hasParamAnnotation;
 
-  public ParamNameResolver(Method method) {
+  public ParamNameResolver(Configuration config, Method method) {
     final Class<?>[] paramTypes = method.getParameterTypes();
     final Annotation[][] paramAnnotations = method.getParameterAnnotations();
     final SortedMap<Integer, String> map = new TreeMap<Integer, String>();
@@ -68,13 +83,33 @@ public ParamNameResolver(Method method) {
           break;
         }
       }
-      // When @Param is not specified, use the parameter index as the name
-      // ("0", "1", ...) gcode issue #71
-      map.put(paramIndex, name == null ? String.valueOf(map.size()) : name);
+      if (name == null) {
+        // @Param was not specified.
+        if (config.isUseActualParamName()) {
+          name = getActualParamName(method, paramIndex);
+        } else {
+          // use the parameter index as the name ("0", "1", ...)
+          // gcode issue #71
+          name = String.valueOf(map.size());
+        }
+      }
+      map.put(paramIndex, name);
     }
     names = Collections.unmodifiableSortedMap(map);
   }
 
+  private String getActualParamName(Method method, int paramIndex) {
+    if (GET_PARAMS == null) {
+      throw new ReflectionException("Method#getParameters() method does not exist. Relaunch on Java 8 or set false to useActualParamName.");
+    }
+    try {
+      Object[] params = (Object[]) GET_PARAMS.invoke(method);
+      return (String) GET_NAME.invoke(params[paramIndex]);
+    } catch (Exception e) {
+      throw new ReflectionException("Error occurred when invoking Method#getParameters().", e);
+    }
+  }
+
   private static boolean isSpecialParameter(Class<?> clazz) {
     return RowBounds.class.isAssignableFrom(clazz) || ResultHandler.class.isAssignableFrom(clazz);
   }

src/main/java/org/apache/ibatis/session/Configuration.java

@@ -106,6 +106,7 @@ public class Configuration {
   protected boolean useColumnLabel = true;
   protected boolean cacheEnabled = true;
   protected boolean callSettersOnNulls = false;
+  protected boolean useActualParamName = false;
 
   protected String logPrefix;
   protected Class <? extends Log> logImpl;
@@ -240,6 +241,14 @@ public void setCallSettersOnNulls(boolean callSettersOnNulls) {
     this.callSettersOnNulls = callSettersOnNulls;
   }
 
+  public boolean isUseActualParamName() {
+    return useActualParamName;
+  }
+
+  public void setUseActualParamName(boolean useActualParamName) {
+    this.useActualParamName = useActualParamName;
+  }
+
   public String getDatabaseId() {
     return databaseId;
   }