corejava第10版

corejava第10版/v2ch08/sourceAnnotations/ToStringAnnotationProcessor.java

@@ -0,0 +1,79 @@
+package sourceAnnotations;
+
+import java.beans.*;
+import java.io.*;
+import java.util.*;
+
+import javax.annotation.processing.*;
+import javax.lang.model.*;
+import javax.lang.model.element.*;
+import javax.tools.*;
+import javax.tools.Diagnostic.Kind;
+
+@SupportedAnnotationTypes("sourceAnnotations.ToString")
+@SupportedSourceVersion(SourceVersion.RELEASE_8)
+public class ToStringAnnotationProcessor extends AbstractProcessor 
+{
+   @Override
+   public boolean process(Set<? extends TypeElement> annotations,
+      RoundEnvironment currentRound) 
+   {
+      if (annotations.size() == 0) return true;
+      try 
+      {
+         JavaFileObject sourceFile = processingEnv.getFiler().createSourceFile("sourceAnnotations.ToStrings");
+         try (PrintWriter out = new PrintWriter(sourceFile.openWriter())) {
+            out.println("// Automatically generated by sourceAnnotations.ToStringAnnotationProcessor");
+            out.println("package sourceAnnotations;");
+            out.println("public class ToStrings {");
+
+            for (Element e : currentRound.getElementsAnnotatedWith(ToString.class)) {
+               if (e instanceof TypeElement) 
+               {
+                  TypeElement te = (TypeElement) e;
+                  writeToStringMethod(out, te);
+               }
+            }   
+             out.println("    public static String toString(Object obj) {");
+             out.println("        return java.util.Objects.toString(obj);");
+             out.println("    }");
+             out.println("}");
+         }
+      } 
+      catch (IOException ex) 
+      {
+         processingEnv.getMessager().printMessage(Kind.ERROR, ex.getMessage());
+      }        
+      return true;
+   }
+    
+   private void writeToStringMethod(PrintWriter out, TypeElement te) 
+   {
+      String className = te.getQualifiedName().toString();
+      out.println("    public static String toString(" + className + " obj) {");
+      ToString ann = te.getAnnotation(ToString.class);
+      out.println("        StringBuilder result = new StringBuilder();");
+      if (ann.includeName()) out.println("        result.append(\"" + className + "\");");        
+      out.println("        result.append(\"[\");");
+      boolean first = true;
+      for (Element c : te.getEnclosedElements()) 
+      {
+         String methodName = c.getSimpleName().toString();
+         ann = c.getAnnotation(ToString.class);
+         if (ann != null) 
+         {             
+            if (first) first = false; else out.println("        result.append(\",\");");
+            if (ann.includeName()) 
+            {
+               String fieldName = Introspector.decapitalize(methodName.replaceAll("^(get|is)", ""));
+                  // Turn getWidth into width, isDone into done, getURL into URL 
+               out.println("        result.append(\"" + fieldName + "=" + "\");"); 
+            }
+            out.println("        result.append(toString(obj." + methodName + "()));");
+         }
+      }
+      out.println("        result.append(\"]\");");
+      out.println("        return result.toString();");
+      out.println("    }");
+   }    
+}