org.sfm.reflect.asm.JdbcMapperAsmBuilder Maven / Gradle / Ivy

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Java library to map flat record - ResultSet, csv - to java object with minimum configuration and low footprint.
There is a newer version: 1.10.3
package org.sfm.reflect.asm;

import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.FieldVisitor;
import org.objectweb.asm.MethodVisitor;
import org.sfm.jdbc.impl.AbstractJdbcMapperImpl;
import org.sfm.map.RowHandlerErrorHandler;
import org.sfm.map.impl.FieldMapper;
import org.sfm.reflect.Instantiator;

import java.sql.ResultSet;

import static org.objectweb.asm.Opcodes.*;

public class JdbcMapperAsmBuilder {

	private static final String ABSTRACT_JDBC_MAPPER_IMPL_TYPE = AsmUtils.toType(AbstractJdbcMapperImpl.class);
	private static final String FIELD_MAPPER_TYPE = AsmUtils.toType(FieldMapper.class);
	private static final String INSTANTIATOR_TYPE = AsmUtils.toType(Instantiator.class);
	private static final String ROW_HANDLER_ERROR_HANDLER_TYPE = AsmUtils.toType(RowHandlerErrorHandler.class);

	public static  byte[] dump (final String className, final FieldMapper[] mappers, final Class target) throws Exception {

		ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS);
		MethodVisitor mv;
		
		Class sourceClass = ResultSet.class;
		final String targetType = AsmUtils.toType(target);
		final String sourceType = AsmUtils.toType(sourceClass);
		final String classType = AsmUtils.toType(className);
		cw.visit(V1_6, ACC_PUBLIC + ACC_FINAL + ACC_SUPER, classType, "L" + ABSTRACT_JDBC_MAPPER_IMPL_TYPE + ";", ABSTRACT_JDBC_MAPPER_IMPL_TYPE, null);

		for(int i = 0; i < mappers.length; i++) {
			declareMapperFields(cw,  mappers[i], i);
		}

		{
			mv = cw.visitMethod(ACC_PUBLIC, "", "([L" + FIELD_MAPPER_TYPE + ";L" + INSTANTIATOR_TYPE + ";L" + ROW_HANDLER_ERROR_HANDLER_TYPE + ";)V", "([L" + FIELD_MAPPER_TYPE +";L" + AsmUtils.toType(Instantiator.class) + ";L" + AsmUtils.toType(RowHandlerErrorHandler.class) + ";)V", null);

			mv.visitCode();
			mv.visitVarInsn(ALOAD, 0);
			mv.visitVarInsn(ALOAD, 2);
			mv.visitVarInsn(ALOAD, 3);
			mv.visitMethodInsn(INVOKESPECIAL, ABSTRACT_JDBC_MAPPER_IMPL_TYPE, "", "(L" + INSTANTIATOR_TYPE + ";L" + ROW_HANDLER_ERROR_HANDLER_TYPE +  ";)V", false);
			
			
			for(int i = 0; i < mappers.length; i++) {
				addGetterSetterInit(mv,  mappers[i], i, classType); 
			}
			
			
			mv.visitInsn(RETURN);
			mv.visitMaxs(3, 3);
			mv.visitEnd();
		}
		
		{
			mv = cw.visitMethod(ACC_PROTECTED + ACC_FINAL, "mapFields", "(L" + sourceType + ";L" + targetType + ";)V", null, new String[] { "java/lang/Exception" });
			mv.visitCode();

			for(int i = 0; i < mappers.length; i++) {
				generateMappingCall(mv, mappers[i], i, classType, sourceType, targetType);
			}
			
			mv.visitInsn(RETURN);
			mv.visitMaxs(3, 3);
		}
		{
			mv = cw.visitMethod(ACC_PROTECTED + ACC_BRIDGE + ACC_SYNTHETIC, "mapFields", "(Ljava/lang/Object;Ljava/lang/Object;)V", null, new String[] { "java/lang/Exception" });
			mv.visitCode();
			mv.visitVarInsn(ALOAD, 0);
			mv.visitVarInsn(ALOAD, 1);
			mv.visitTypeInsn(CHECKCAST, sourceType);
			mv.visitVarInsn(ALOAD, 2);
			mv.visitTypeInsn(CHECKCAST, targetType);
			mv.visitMethodInsn(INVOKEVIRTUAL, classType, "mapFields", "(L" + sourceType + ";L" + targetType + ";)V", false);
			mv.visitInsn(RETURN);
			mv.visitMaxs(3, 3);
			mv.visitEnd();
		}
		

		cw.visitEnd();

		return AsmUtils.writeClassToFile(className, cw.toByteArray());
	}

	private static  void generateMappingCall(MethodVisitor mv,
			FieldMapper mapper, int index, String classType, String sourceType, String targetType) {
		if (mapper ==null) return;
		Class mapperClass = AsmUtils.getPublicOrInterfaceClass(mapper.getClass());
		mv.visitVarInsn(ALOAD, 0);
		mv.visitFieldInsn(GETFIELD, classType, "mapper" + index, "L" +  AsmUtils.toType(mapperClass) + ";");
		mv.visitVarInsn(ALOAD, 1);
		mv.visitVarInsn(ALOAD, 2);
		if (AsmUtils.isStillGeneric(mapperClass)) {
			AsmUtils.invoke(mv, mapperClass, "map", "(Ljava/lang/Object;Ljava/lang/Object;)V");
		} else {
			AsmUtils.invoke(mv, mapperClass, "map", "(L" + sourceType + ";L" + targetType +";)V");
		}

	}

	private static  void addGetterSetterInit(MethodVisitor mv,
			FieldMapper mapper, int index, String classType) {
		if (mapper == null) return;
		Class mapperClass = mapper.getClass();
		
		mv.visitVarInsn(ALOAD, 0);
		mv.visitVarInsn(ALOAD, 1);
		addIndex(mv, index);
		mv.visitInsn(AALOAD);
		mv.visitTypeInsn(CHECKCAST, AsmUtils.toType(mapperClass));
		mv.visitFieldInsn(PUTFIELD, classType, "mapper" + index, "L" +  AsmUtils.toType(mapperClass) +";");

	}

	private static  void declareMapperFields(ClassWriter cw,
			FieldMapper mapper, int index) {
		if (mapper == null) 
			return;
		
		FieldVisitor fv;
		Class mapperClass = AsmUtils.getPublicOrInterfaceClass(mapper.getClass());
		
		fv = cw.visitField(ACC_PRIVATE + ACC_FINAL, "mapper" + index, "L" + AsmUtils.toType(mapperClass) + ";", "L" + AsmUtils.toTypeWithParam(mapperClass) + ";", null);
		fv.visitEnd();

	}

	private static void addIndex(MethodVisitor mv, int i) {
		switch(i) {
		case 0:
			mv.visitInsn(ICONST_0);
			return;
		case 1:
			mv.visitInsn(ICONST_1);
			return;
		case 2:
			mv.visitInsn(ICONST_2);
			return;
		case 3:
			mv.visitInsn(ICONST_3);
			return;
		case 4:
			mv.visitInsn(ICONST_4);
			return;
		case 5:
			mv.visitInsn(ICONST_5);
			return;
		default:
			mv.visitIntInsn(BIPUSH, i);
		}
	}
}