使用GenericService调用dubbo接口的时候,发现抛出来的自定义异常都变成了GenericExecption。于是跟踪了源码看了一下,发现在GenericFilter中有一段
Result result = invoker.invoke(new RpcInvocation(method, args, inv.getAttachments()));
if ((result.hasException()) &&
(!(result
.getException() instanceof GenericException))) {
return new RpcResult(new GenericException(result.getException()));
}
这样就所有的非GenericException都转换成了GenericException
于是想到在服务提供方增加一个拦截器来实现自己想要的功能!具体实现如下:
import java.io.IOException;
import java.lang.reflect.Method;
import com.alibaba.dubbo.common.Constants;
import com.alibaba.dubbo.common.extension.Activate;
import com.alibaba.dubbo.common.extension.ExtensionLoader;
import com.alibaba.dubbo.common.io.UnsafeByteArrayInputStream;
import com.alibaba.dubbo.common.io.UnsafeByteArrayOutputStream;
import com.alibaba.dubbo.common.serialize.Serialization;
import com.alibaba.dubbo.common.utils.PojoUtils;
import com.alibaba.dubbo.common.utils.ReflectUtils;
import com.alibaba.dubbo.common.utils.StringUtils;
import com.alibaba.dubbo.rpc.Filter;
import com.alibaba.dubbo.rpc.Invocation;
import com.alibaba.dubbo.rpc.Invoker;
import com.alibaba.dubbo.rpc.Result;
import com.alibaba.dubbo.rpc.RpcException;
import com.alibaba.dubbo.rpc.RpcInvocation;
import com.alibaba.dubbo.rpc.RpcResult;
import com.alibaba.dubbo.rpc.service.GenericException;
import com.alibaba.dubbo.rpc.support.ProtocolUtils;
/**
* 这里order的源码是-20000,因为我们要执行在原逻辑之前
* 因此我们这里改成了-25000
**/
@Activate(group = Constants.PROVIDER, order = -25000)
public class CustomGenericFilter implements Filter {
@Override
public Result invoke(Invoker<?> invoker, Invocation inv) throws RpcException {
if (inv.getMethodName().equals(Constants.$INVOKE)
&& inv.getArguments() != null
&& inv.getArguments().length == 3
&& ! invoker.getUrl().getParameter(Constants.GENERIC_KEY, false)) {
String name = ((String) inv.getArguments()[0]).trim();
String[] types = (String[]) inv.getArguments()[1];
Object[] args = (Object[]) inv.getArguments()[2];
try {
Method method = ReflectUtils.findMethodByMethodSignature(invoker.getInterface(), name, types);
Class<?>[] params = method.getParameterTypes();
if (args == null) {
args = new Object[params.length];
}
String generic = inv.getAttachment(Constants.GENERIC_KEY);
if (StringUtils.isEmpty(generic)
|| ProtocolUtils.isDefaultGenericSerialization(generic)) {
args = PojoUtils.realize(args, params, method.getGenericParameterTypes());
} else if (ProtocolUtils.isJavaGenericSerialization(generic)) {
for(int i = 0; i < args.length; i++) {
if (byte[].class == args[i].getClass()) {
try {
UnsafeByteArrayInputStream is = new UnsafeByteArrayInputStream((byte[])args[i]);
args[i] = ExtensionLoader.getExtensionLoader(Serialization.class)
.getExtension(Constants.GENERIC_SERIALIZATION_NATIVE_JAVA)
.deserialize(null, is).readObject();
} catch (Exception e) {
throw new RpcException("Deserialize argument [" + (i + 1) + "] failed.", e);
}
} else {
throw new RpcException(
new StringBuilder(32).append("Generic serialization [")
.append(Constants.GENERIC_SERIALIZATION_NATIVE_JAVA)
.append("] only support message type ")
.append(byte[].class)
.append(" and your message type is ")
.append(args[i].getClass()).toString());
}
}
}
Result result = invoker.invoke(new RpcInvocation(method, args, inv.getAttachments()));
if (result.hasException()
&& ! (result.getException() instanceof GenericException)) {
/*********************和源码不一样的地方**********************/
if(result.getException() instanceof XXXException){
return new RpcResult(result.getException());
}else{
return new RpcResult(new GenericException(result.getException()));
}
/*********************和源码不一样的地方_结束**********************/
}
if (ProtocolUtils.isJavaGenericSerialization(generic)) {
try {
UnsafeByteArrayOutputStream os = new UnsafeByteArrayOutputStream(512);
ExtensionLoader.getExtensionLoader(Serialization.class)
.getExtension(Constants.GENERIC_SERIALIZATION_NATIVE_JAVA)
.serialize(null, os).writeObject(result.getValue());
return new RpcResult(os.toByteArray());
} catch (IOException e) {
throw new RpcException("Serialize result failed.", e);
}
} else {
return new RpcResult(PojoUtils.generalize(result.getValue()));
}
} catch (NoSuchMethodException e) {
throw new RpcException(e.getMessage(), e);
} catch (ClassNotFoundException e) {
throw new RpcException(e.getMessage(), e);
}
}
return invoker.invoke(inv);
}
}
当然不要忘记将filter配置到META-INF和spring的配置文件中,关于filter的配置见:dubbo配置filter隐式传参
当然此处也可以直接修改dubbo的源码,不过dubbo既然提供了filter能处理这个问题,最好还是不要去动源码了!