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Java library to map flat record - ResultSet, csv - to java object with minimum configuration and low footprint.
package org.sfm.reflect.asm;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.sfm.reflect.Getter;
import org.sfm.reflect.primitive.IntGetter;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
public class GetterBuilder implements Opcodes {
private static final String GETTER_TYPE = AsmUtils.toType(Getter.class);
private static final String ORG_SFM_REFLECT_PRIMITIVE = AsmUtils.toType(IntGetter.class.getPackage().getName());
public static byte[] createObjectGetter(final String className, final Field field) throws Exception {
ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS);
MethodVisitor mv;
Class target = field.getDeclaringClass();
Class property = field.getType();
String targetType = toType(target);
String propertyType = toType(property);
String classType = toType(className);
cw.visit(
V1_6,
ACC_PUBLIC + ACC_FINAL + ACC_SUPER,
classType,
"Ljava/lang/Object;L" + GETTER_TYPE + ";",
"java/lang/Object", new String[] {GETTER_TYPE});
{
mv = cw.visitMethod(ACC_PUBLIC, "", "()V", null, null);
mv.visitCode();
mv.visitVarInsn(ALOAD, 0);
mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "", "()V", false);
mv.visitInsn(RETURN);
mv.visitMaxs(1, 1);
mv.visitEnd();
}
{
mv = cw.visitMethod(ACC_PUBLIC, "get",
"(L" + targetType + ";)" + AsmUtils.toTypeParam(propertyType), null,
new String[] { "java/lang/Exception" });
mv.visitCode();
mv.visitVarInsn(ALOAD, 1);
mv.visitFieldInsn(GETFIELD, targetType, field.getName(), AsmUtils.toTypeParam(propertyType));
mv.visitInsn(ARETURN);
mv.visitMaxs(1, 2);
mv.visitEnd();
}
appendBridge(cw, targetType, propertyType, classType);
appendToString(cw);
cw.visitEnd();
return AsmUtils.writeClassToFile(className, cw.toByteArray());
}
public static byte[] createObjectGetter(final String className, final Method method) throws Exception {
ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS);
MethodVisitor mv;
Class target = method.getDeclaringClass();
Class property = method.getReturnType();
String targetType = toType(target);
String propertyType = toType(property);
String classType = toType(className);
cw.visit(
V1_6,
ACC_PUBLIC + ACC_FINAL + ACC_SUPER,
classType,
"Ljava/lang/Object;L" + GETTER_TYPE + ";",
"java/lang/Object", new String[] {GETTER_TYPE});
{
mv = cw.visitMethod(ACC_PUBLIC, "", "()V", null, null);
mv.visitCode();
mv.visitVarInsn(ALOAD, 0);
mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "", "()V", false);
mv.visitInsn(RETURN);
mv.visitMaxs(1, 1);
mv.visitEnd();
}
{
mv = cw.visitMethod(ACC_PUBLIC, "get",
"(L" + targetType + ";)" + AsmUtils.toTypeParam(propertyType), null,
new String[] { "java/lang/Exception" });
mv.visitCode();
mv.visitVarInsn(ALOAD, 1);
AsmUtils.invoke(mv, target, method.getName(), "()" + AsmUtils.toTypeParam(propertyType));
mv.visitInsn(ARETURN);
mv.visitMaxs(1, 2);
mv.visitEnd();
}
appendBridge(cw, targetType, propertyType, classType);
appendToString(cw);
cw.visitEnd();
return AsmUtils.writeClassToFile(className, cw.toByteArray());
}
private static void appendBridge(ClassWriter cw, String targetType, String propertyType, String classType) {
MethodVisitor mv;
mv = cw.visitMethod(ACC_PUBLIC + ACC_BRIDGE + ACC_SYNTHETIC, "get", "(Ljava/lang/Object;)Ljava/lang/Object;", null, new String[] { "java/lang/Exception" });
mv.visitCode();
mv.visitVarInsn(ALOAD, 0);
mv.visitVarInsn(ALOAD, 1);
mv.visitTypeInsn(CHECKCAST, targetType);
mv.visitMethodInsn(INVOKEVIRTUAL, classType, "get", "(L" + targetType + ";)" + AsmUtils.toTypeParam(propertyType), false);
mv.visitInsn(ARETURN);
mv.visitMaxs(2, 2);
mv.visitEnd();
}
public static byte[] createPrimitiveGetter(String className, Field field) throws Exception {
ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS);
MethodVisitor mv;
Class target = field.getDeclaringClass();
Class primitive = field.getType();
Class property = AsmUtils.wrappers.get(primitive);
String targetType = toType(target);
String primitiveType = AsmUtils.primitivesType.get(primitive);
String propertyType = toType(property);
String classType = toType(className);
String methodSuffix = property.getSimpleName();
if ("Integer".equals(methodSuffix)) {
methodSuffix = "Int";
}
String getMethod = "get" + methodSuffix;
cw.visit(V1_6, ACC_PUBLIC + ACC_FINAL + ACC_SUPER, classType,
"Ljava/lang/Object;"
+ "L" + GETTER_TYPE + ";"
+ "L" + ORG_SFM_REFLECT_PRIMITIVE + methodSuffix + "Getter;",
"java/lang/Object",
new String[] {GETTER_TYPE,
ORG_SFM_REFLECT_PRIMITIVE + "/" + methodSuffix + "Getter" });
{
mv = cw.visitMethod(ACC_PUBLIC, "", "()V", null, null);
mv.visitCode();
mv.visitVarInsn(ALOAD, 0);
mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "", "()V", false);
mv.visitInsn(RETURN);
mv.visitMaxs(1, 1);
mv.visitEnd();
}
{
mv = cw.visitMethod(ACC_PUBLIC, getMethod, "(L" + targetType + ";)" + primitiveType , null, new String[] { "java/lang/Exception" });
mv.visitCode();
mv.visitVarInsn(ALOAD, 1);
mv.visitFieldInsn(GETFIELD, targetType, field.getName(), primitiveType);
mv.visitInsn(AsmUtils.returnOps.get(primitive));
mv.visitMaxs(1, 2);
mv.visitEnd();
}
{
mv = cw.visitMethod(ACC_PUBLIC, "get", "(L" + targetType + ";)" + AsmUtils.toTypeParam(propertyType), null, new String[] { "java/lang/Exception" });
mv.visitCode();
mv.visitVarInsn(ALOAD, 1);
mv.visitFieldInsn(GETFIELD, targetType, field.getName(), primitiveType);
mv.visitMethodInsn(INVOKESTATIC, propertyType, "valueOf", "(" + primitiveType + ")L" + propertyType + ";" , false);
mv.visitInsn(ARETURN);
mv.visitMaxs(1, 2);
mv.visitEnd();
}
appendPrimitiveBridges(cw, primitive, targetType, primitiveType, propertyType, classType, getMethod);
appendToString(cw);
cw.visitEnd();
return AsmUtils.writeClassToFile(className, cw.toByteArray());
}
public static byte[] createPrimitiveGetter(String className, Method method) throws Exception {
ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS);
MethodVisitor mv;
Class target = method.getDeclaringClass();
Class primitive = method.getReturnType();
Class property = AsmUtils.wrappers.get(primitive);
String targetType = toType(target);
String primitiveType = AsmUtils.primitivesType.get(primitive);
String propertyType = toType(property);
String classType = toType(className);
String methodSuffix = property.getSimpleName();
if ("Integer".equals(methodSuffix)) {
methodSuffix = "Int";
}
String getMethod = "get" + methodSuffix;
cw.visit(V1_6, ACC_PUBLIC + ACC_FINAL + ACC_SUPER, classType,
"Ljava/lang/Object;"
+ "L" + GETTER_TYPE + ";"
+ "L" + ORG_SFM_REFLECT_PRIMITIVE + methodSuffix + "Getter;",
"java/lang/Object",
new String[] {GETTER_TYPE,
ORG_SFM_REFLECT_PRIMITIVE + "/" + methodSuffix + "Getter" });
{
mv = cw.visitMethod(ACC_PUBLIC, "", "()V", null, null);
mv.visitCode();
mv.visitVarInsn(ALOAD, 0);
mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "", "()V", false);
mv.visitInsn(RETURN);
mv.visitMaxs(1, 1);
mv.visitEnd();
}
{
mv = cw.visitMethod(ACC_PUBLIC, getMethod, "(L" + targetType + ";)" + primitiveType , null, new String[] { "java/lang/Exception" });
mv.visitCode();
mv.visitVarInsn(ALOAD, 1);
AsmUtils.invoke(mv, target, method.getName(), "()" + primitiveType);
mv.visitInsn(AsmUtils.returnOps.get(primitive));
mv.visitMaxs(1, 2);
mv.visitEnd();
}
{
mv = cw.visitMethod(ACC_PUBLIC, "get", "(L" + targetType + ";)" + AsmUtils.toTypeParam(propertyType), null, new String[] { "java/lang/Exception" });
mv.visitCode();
mv.visitVarInsn(ALOAD, 1);
AsmUtils.invoke(mv, target, method.getName(), "()" + primitiveType);
mv.visitMethodInsn(INVOKESTATIC, propertyType, "valueOf", "(" + primitiveType + ")L" + propertyType + ";" , false);
mv.visitInsn(ARETURN);
mv.visitMaxs(1, 2);
mv.visitEnd();
}
appendPrimitiveBridges(cw, primitive, targetType, primitiveType, propertyType, classType, getMethod);
appendToString(cw);
cw.visitEnd();
return AsmUtils.writeClassToFile(className, cw.toByteArray());
}
private static void appendPrimitiveBridges(ClassWriter cw, Class primitive, String targetType, String primitiveType, String propertyType, String classType, String getMethod) {
MethodVisitor mv;
{
mv = cw.visitMethod(ACC_PUBLIC + ACC_BRIDGE + ACC_SYNTHETIC, getMethod, "(Ljava/lang/Object;)" + primitiveType, null, new String[] { "java/lang/Exception" });
mv.visitCode();
mv.visitVarInsn(ALOAD, 0);
mv.visitVarInsn(ALOAD, 1);
mv.visitTypeInsn(CHECKCAST, targetType);
mv.visitMethodInsn(INVOKEVIRTUAL, classType , getMethod, "(L" + targetType + ";)" + primitiveType, false);
mv.visitInsn(AsmUtils.returnOps.get(primitive));
mv.visitMaxs(2, 2);
mv.visitEnd();
}
{
mv = cw.visitMethod(ACC_PUBLIC + ACC_BRIDGE + ACC_SYNTHETIC, "get", "(Ljava/lang/Object;)Ljava/lang/Object;", null, new String[] { "java/lang/Exception" });
mv.visitCode();
mv.visitVarInsn(ALOAD, 0);
mv.visitVarInsn(ALOAD, 1);
mv.visitTypeInsn(CHECKCAST, targetType );
mv.visitMethodInsn(INVOKEVIRTUAL, classType , "get", "(L" + targetType + ";)" + AsmUtils.toTypeParam(propertyType), false);
mv.visitInsn(ARETURN);
mv.visitMaxs(2, 2);
mv.visitEnd();
}
}
private static void appendToString(ClassWriter cw) {
MethodVisitor mv;
mv = cw.visitMethod(ACC_PUBLIC, "toString", "()Ljava/lang/String;", null, null);
mv.visitCode();
mv.visitTypeInsn(NEW, "java/lang/StringBuilder");
mv.visitInsn(DUP);
mv.visitMethodInsn(INVOKESPECIAL, "java/lang/StringBuilder", "", "()V", false);
mv.visitVarInsn(ASTORE, 1);
mv.visitVarInsn(ALOAD, 1);
mv.visitVarInsn(ALOAD, 0);
mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Object", "getClass", "()Ljava/lang/Class;", false);
mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Class", "getSimpleName", "()Ljava/lang/String;", false);
mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append", "(Ljava/lang/String;)Ljava/lang/StringBuilder;", false);
mv.visitLdcInsn("{");
mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append", "(Ljava/lang/String;)Ljava/lang/StringBuilder;", false);
mv.visitLdcInsn("}");
mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append", "(Ljava/lang/String;)Ljava/lang/StringBuilder;", false);
mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "toString", "()Ljava/lang/String;", false);
mv.visitInsn(ARETURN);
mv.visitMaxs(2, 1);
mv.visitEnd();
}
private static String toType(Class target) {
String name = target.getName();
return toType(name);
}
private static String toType(String name) {
return name.replace('.', '/');
}
}