Dubbo SPI-Adaptive详解

https://www.jianshu.com/p/dc616814ce98

一、四个测试用例

  准备如下

import com.alibaba.dubbo.common.URL;
import com.alibaba.dubbo.common.extension.Adaptive;
import com.alibaba.dubbo.common.extension.SPI;
@SPI
public interface AdaptiveExt2 {
    @Adaptive
    String echo(String msg, URL url);
}
三个实现类
public class DubboAdaptiveExt2 implements AdaptiveExt2 {
    @Override
    public String echo(String msg, URL url) {
        return "dubbo";
    }
}
public class SpringCloudAdaptiveExt2 implements AdaptiveExt2 {
    @Override
    public String echo(String msg, URL url) {
        return "spirng cloud";
    }
}
public class ThriftAdaptiveExt2 implements AdaptiveExt2 {
    @Override
    public String echo(String msg, URL url) {
        return "thrift";
    }
}

在Resource目录下,添加/META-INF/dubbo/internal/com.example.dubbo.adaptive.AdaptiveExt2

dubbo=com.example.dubbo.adaptive.DubboAdaptiveExt2
cloud=com.example.dubbo.adaptive.SpringCloudAdaptiveExt2
thrift=com.example.dubbo.adaptive.ThriftAdaptiveExt2

测试1. SPI注解上有value值

@SPI("dubbo")
public interface AdaptiveExt2 {
    @Adaptive
    String echo(String msg, URL url);
}
@Test
    public void testdubbo(){
        // @SPI("dubbo")
        ExtensionLoader<AdaptiveExt2> loader = ExtensionLoader.getExtensionLoader(AdaptiveExt2.class);
        AdaptiveExt2 adaptiveExtension = loader.getAdaptiveExtension();
        URL url = URL.valueOf("test://loalhost/test");
        System.out.println(adaptiveExtension.echo("d",url));
    }
结果
dubbo

 测试2 SPI注解上有value值,URL上也有具体的值

@SPI("dubbo")
public interface AdaptiveExt2 {
    @Adaptive
    String echo(String msg, URL url);
}
    @Test
    public void testdubbo2(){
        // @SPI("dubbo")
        // +?adaptive.ext2=cloud
        ExtensionLoader<AdaptiveExt2> loader = ExtensionLoader.getExtensionLoader(AdaptiveExt2.class);
        AdaptiveExt2 adaptiveExtension = loader.getAdaptiveExtension();
        URL url = URL.valueOf("test://loalhost/test?adaptive.ext2=cloud");
        System.out.println(adaptiveExtension.echo("d",url));
    }
结果
spirng cloud
说明 RUL优先于SPI注解的value值

 测试3 SPI注解有value值,URL中也有具体的值,实现类上有@Adaptive注解

@SPI("dubbo")
public interface AdaptiveExt2 {
    @Adaptive
    String echo(String msg, URL url);
}
@Adaptive
public class ThriftAdaptiveExt2 implements AdaptiveExt2 {
    @Override
    public String echo(String msg, URL url) {
        return "thrift";
    }
}
    @Test
    public void testdubbo3(){
        // @Adaptive
        //public class ThriftAdaptiveExt2
        //+?adaptive.ext2=cloud
        ExtensionLoader<AdaptiveExt2> loader = ExtensionLoader.getExtensionLoader(AdaptiveExt2.class);
        AdaptiveExt2 adaptiveExtension = loader.getAdaptiveExtension();
        URL url = URL.valueOf("test://loalhost/test?adaptive.ext2=cloud");
        System.out.println(adaptiveExtension.echo("d",url));
    }
结果
thrift
说明 实现类的@Adaptive注解优先于URL 

 测试4 SPI注解中有value值,实现类上没有@Adaptive注解,在方法上打上@Adaptive注解,注解中的value与链接中的参数key一致,

@SPI("dubbo")
public interface AdaptiveExt2 {
    @Adaptive({"t"})
    String echo(String msg, URL url);
}
    @Test
    public void testdubbo4(){
        // @SPI("dubbo")
        //public interface AdaptiveExt2 {
        //    @Adaptive({"t"})
        //    String echo(String msg, URL url);
        // ?t=cloud
        ExtensionLoader<AdaptiveExt2> loader = ExtensionLoader.getExtensionLoader(AdaptiveExt2.class);
        AdaptiveExt2 adaptiveExtension = loader.getAdaptiveExtension();
        URL url = URL.valueOf("test://loalhost/test?t=cloud");
        System.out.println(adaptiveExtension.echo("d",url));
    }

结果 
spirng cloud

 测试结论:

  1.在类上加@Adaptive注解的类,是最明确的创建对应类型的Adaptive类。所有它的优先级最高

  2.@SPI注解的value值是默认值,如果通过URL获取不到关于取那个类作为Adaptive类的话,就是用这个默认值,当然如果URL中可以获取到,就用URL中的

  3.可以在方法上增加@Adaptive注解,注解中value与链接中的参数key一致,连接中的key对应的value就是spi中的name,获取对应的实现类

 

源码分析:

 

ExtensionLoader<AdaptiveExt2> loader = ExtensionLoader.getExtensionLoader(AdaptiveExt2.class);

  @SuppressWarnings("unchecked")
  public static <T> ExtensionLoader<T> getExtensionLoader(Class<T> type) {
        if (type == null)
            throw new IllegalArgumentException("Extension type == null");
        if(!type.isInterface()) {
            throw new IllegalArgumentException("Extension type(" + type + ") is not interface!");
        }
        // 这个类型必须加上SPI注解,否则报错
        if(!withExtensionAnnotation(type)) {
            throw new IllegalArgumentException("Extension type(" + type + 
                    ") is not extension, because WITHOUT @" + SPI.class.getSimpleName() + " Annotation!");
        }
        // 从缓存中获取
        ExtensionLoader<T> loader = (ExtensionLoader<T>) EXTENSION_LOADERS.get(type);
        if (loader == null) {
            EXTENSION_LOADERS.putIfAbsent(type, new ExtensionLoader<T>(type));
            loader = (ExtensionLoader<T>) EXTENSION_LOADERS.get(type);
        }
        return loader;
  }    

 

  先检查SPI注解,再缓存中查询对应ExtensionLoader,dubbo中的spi大量利用了本地缓存。

// 构造方法私有化
  private ExtensionLoader(Class<?> type) {
        this.type = type;
       // 如果type是ExtensionFactory类型,那么objectFactory是null,否则是ExtensionFactory类型的适配器
        objectFactory = (type == ExtensionFactory.class ? null : ExtensionLoader.getExtensionLoader(ExtensionFactory.class).getAdaptiveExtension());
  }    

  两点:

    1.构造方法私有化,不能通过外部实例化

    2.objectFactory是ioc功能

  开始获取adaptive对象

 

    @SuppressWarnings("unchecked")
    public T getAdaptiveExtension() {
        Object instance = cachedAdaptiveInstance.get();
        if (instance == null) {
            if(createAdaptiveInstanceError == null) {
                synchronized (cachedAdaptiveInstance) {
                    instance = cachedAdaptiveInstance.get();
                    if (instance == null) {
                        try {
                            // 缓存获取不到就创建
                            instance = createAdaptiveExtension();
                            cachedAdaptiveInstance.set(instance);
                        } catch (Throwable t) {
                            createAdaptiveInstanceError = t;
                            throw new IllegalStateException("fail to create adaptive instance: " + t.toString(), t);
                        }
                    }
                }
            }
            else {
                throw new IllegalStateException("fail to create adaptive instance: " + createAdaptiveInstanceError.toString(), createAdaptiveInstanceError);
            }
        }

        return (T) instance;
    }

  第一次从缓存中获取就创建

    @SuppressWarnings("unchecked")
    private T createAdaptiveExtension() {
        try {
            return injectExtension((T) getAdaptiveExtensionClass().newInstance());
        } catch (Exception e) {
            throw new IllegalStateException("Can not create adaptive extenstion " + type + ", cause: " + e.getMessage(), e);
        }
    }

  获取到适配器类的Class,利用反射船舰适配器类的实例,injectExtension是dubbo的DI,依赖注入,如果适配器类有属性的set方法,就会自动注入。

    private Class<?> getAdaptiveExtensionClass() {
        // 触发SPI流程的扫描
        getExtensionClasses();
        // 如果通过上面的步骤可以获取到cacheAdaptiveClass直接返回,如果不行就自行利用动态代理创建一个
        if (cachedAdaptiveClass != null) {
            return cachedAdaptiveClass;
        }
        // 利用动态代理创建一个扩展类
        return cachedAdaptiveClass = createAdaptiveExtensionClass();
    }    

  首先先看getExtensionClasses

  private Map<String, Class<?>> getExtensionClasses() {
        Map<String, Class<?>> classes = cachedClasses.get();
        if (classes == null) {
            synchronized (cachedClasses) {
                classes = cachedClasses.get();
                if (classes == null) {
                    classes = loadExtensionClasses();
                    cachedClasses.set(classes);
                }
            }
        }
        return classes;
  }

  从缓存中取,也就是说加载流程只触发一次,然后放入缓存,后续从缓存中取

    // 此方法已经getExtensionClasses方法同步过。
    private Map<String, Class<?>> loadExtensionClasses() {
   // 获取到类型SPI注解,所以利用SPI扩展点的地方,需要加入SPI注解 final SPI defaultAnnotation = type.getAnnotation(SPI.class); if(defaultAnnotation != null) { String value = defaultAnnotation.value(); if(value != null && (value = value.trim()).length() > 0) { String[] names = NAME_SEPARATOR.split(value); if(names.length > 1) { throw new IllegalStateException("more than 1 default extension name on extension " + type.getName() + ": " + Arrays.toString(names)); }
   // 如果注解中有value,说明有默认的实现,那么将value放到cacheDefaultName中 if(names.length == 1) cachedDefaultName = names[0]; } } // 从 META-INF/dubbo/internal/...读取数据 Map<String, Class<?>> extensionClasses = new HashMap<String, Class<?>>(); loadFile(extensionClasses, DUBBO_INTERNAL_DIRECTORY); loadFile(extensionClasses, DUBBO_DIRECTORY); loadFile(extensionClasses, SERVICES_DIRECTORY); return extensionClasses; }

  获取type上SPI注解,如果里面有value值就赋值给cacheDefaultName变量,随后从META-INF/dubbo/internal/ 、META-INF/dubbo/、META-INF/services/ 这三个路径下搜索对应的文件。

  

    private void loadFile(Map<String, Class<?>> extensionClasses, String dir) {
        String fileName = dir + type.getName();
        try {
            Enumeration<java.net.URL> urls;
            ClassLoader classLoader = findClassLoader();
            if (classLoader != null) {
                urls = classLoader.getResources(fileName);
            } else {
                urls = ClassLoader.getSystemResources(fileName);
            }
            if (urls != null) {
                while (urls.hasMoreElements()) {
                    java.net.URL url = urls.nextElement();
                    try {
                        BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream(), "utf-8"));
                        try {
                            String line = null;
                            while ((line = reader.readLine()) != null) {
                   // 排除一些# 注释的内容 final int ci = line.indexOf('#'); if (ci >= 0) line = line.substring(0, ci); line = line.trim(); if (line.length() > 0) { try { String name = null;
                        // 使用 = 进行分割 name=全路径名称 int i = line.indexOf('='); if (i > 0) { name = line.substring(0, i).trim(); line = line.substring(i + 1).trim(); } if (line.length() > 0) {
                          // 加载解析出的类的全限定名称 Class<?> clazz = Class.forName(line, true, classLoader);
                          // 判断新家在的clazz是否是type的子类,不是则报错 if (! type.isAssignableFrom(clazz)) { throw new IllegalStateException("Error when load extension class(interface: " + type + ", class line: " + clazz.getName() + "), class " + clazz.getName() + "is not subtype of interface."); }
                          // 判断这个加载的类上有没有@Adaptive注解, if (clazz.isAnnotationPresent(Adaptive.class)) { if(cachedAdaptiveClass == null) {
                                // 将此类作为cacheAdaptiveClass cachedAdaptiveClass = clazz; } else if (! cachedAdaptiveClass.equals(clazz)) {
                                // 多个adaptive类的实例,报错 throw new IllegalStateException("More than 1 adaptive class found: " + cachedAdaptiveClass.getClass().getName() + ", " + clazz.getClass().getName()); } } else {
                             // 如果这个类没有@Adaptive注解 try {
                               // 查看这个类有没有此类型的构造方法(主要是为了Wrapper类使用,如果有说明是个wrapper类) clazz.getConstructor(type); Set<Class<?>> wrappers = cachedWrapperClasses; if (wrappers == null) { cachedWrapperClasses = new ConcurrentHashSet<Class<?>>(); wrappers = cachedWrapperClasses; }
                                // 将此warpper放入warpper容器中,也就是cacheWrapperClasses里面 wrappers.add(clazz); } catch (NoSuchMethodException e) {
                                // 不是wrapper类,就会抛出异常执行这里, clazz.getConstructor(); if (name == null || name.length() == 0) {
                                 // 如果name没有写,就是用默认规则生成一个 name = findAnnotationName(clazz); if (name == null || name.length() == 0) { if (clazz.getSimpleName().length() > type.getSimpleName().length() && clazz.getSimpleName().endsWith(type.getSimpleName())) { name = clazz.getSimpleName().substring(0, clazz.getSimpleName().length() - type.getSimpleName().length()).toLowerCase(); } else { throw new IllegalStateException("No such extension name for the class " + clazz.getName() + " in the config " + url); } } } String[] names = NAME_SEPARATOR.split(name); if (names != null && names.length > 0) {
                                    // 看下这个类上有没有@adaptive注解 Activate activate = clazz.getAnnotation(Activate.class); if (activate != null) {
                                    // 存在就在cacheAdaptivates里面添加名称与注解 cachedActivates.put(names[0], activate); } for (String n : names) { if (! cachedNames.containsKey(clazz)) {
                                      // 将此类型的实例与name放入cacheNames cachedNames.put(clazz, n); } Class<?> c = extensionClasses.get(n); if (c == null) {
                                      // 最后往wxtensionClasses添加名称与class extensionClasses.put(n, clazz); } else if (c != clazz) { throw new IllegalStateException("Duplicate extension " + type.getName() + " name " + n + " on " + c.getName() + " and " + clazz.getName()); } } } } } } } catch (Throwable t) { IllegalStateException e = new IllegalStateException("Failed to load extension class(interface: " + type + ", class line: " + line + ") in " + url + ", cause: " + t.getMessage(), t); exceptions.put(line, e); } } } // end of while read lines } finally { reader.close(); } } catch (Throwable t) { logger.error("Exception when load extension class(interface: " + type + ", class file: " + url + ") in " + url, t); } } // end of while urls } } catch (Throwable t) { logger.error("Exception when load extension class(interface: " + type + ", description file: " + fileName + ").", t); } }

  classLoader.getResources 方法获取到的Enumeration<java.net.URL>类型的对象,随后就是遍历

  dubbo=shuqi.dubbotest.spi.adaptive.DubboAdaptiveExt2
  cloud=shuqi.dubbotest.spi.adaptive.SpringCloudAdaptiveExt2
  thrift=shuqi.dubbotest.spi.adaptive.ThriftAdaptiveExt2
如果有#,#后面就是注释,前面是业务数据
如果有=,就按照=进行分割,前面是扩展名称,后面是扩展的全限定类名,方便利用反射加载进来
首先判断一下是不是传入类(type)类型的实例,不是的话:报错
如果类上有@Adaptive注解,那么将这个类赋值给擦车的AdaptiveClass,因为是系统指定的适配类,优先级最高。
  如果多个类上打了@Adaptive注解会报错,“More than 1 adaptive class found:.....”
如果扩展类上没有打上@Adaptive注解:
  第一步:会验证有没有type这个类型作为入参的构造方法 (因为Wrapper,有的类型需要包装一下例如ProtocolFilterWoapper和ProtocolListenerWrapper)
  第二步:没有这种类型的构造方法,就是正常的type类型的实例
如果没有声明name名称就根据类名创建一个名称
查看类上有没有@Adaptive注解:
  有:将名称与注解放到擦车的Activates这个Map中进行缓存
将扩展类和名称放入cachedNames这个Map中进行缓存,将名称和扩展类的class放入传递进来的extensionClsses中
最后这个extensionClasses会被返回出来被使用。

  接下来回到getAdaptiveExtensionClss()方法
    private Class<?> getAdaptiveExtensionClass() {
        // 触发SPI流程的扫描
        getExtensionClasses();
        // 如果通过上面的步骤可以获取到cacheAdaptiveClass直接返回,如果不行就自行利用动态代理创建一个
        if (cachedAdaptiveClass != null) {
            return cachedAdaptiveClass;
        }
        // 利用动态代理创建一个扩展类
        return cachedAdaptiveClass = createAdaptiveExtensionClass();
    }  

  如果cachedAdaptiveClss不为空就返回,那什么情况下不为空?当扩展类打上@Adaptive注解的时候,就会直接将这个类返回。如果没有注解,就得自己生成一个也就是createAdaptiveExtensionClass

  
  private Class<?> createAdaptiveExtensionClass() {
      // 创建代码的字符串形式 String code = createAdaptiveExtensionClassCode();
      // 寻找类加载器 ClassLoader classLoader = findClassLoader();
      // 寻找Compiler的适配器扩展类 com.alibaba.dubbo.common.compiler.Compiler compiler = ExtensionLoader.getExtensionLoader(com.alibaba.dubbo.common.compiler.Compiler.class).getAdaptiveExtension();  // 进行编译成class的实例返回
     return compiler.compile(code, classLoader); }

  将类以字符串的形式拼接出来,然后利用编译器进行编译,返回编译后的class对象。

  /**
  * 创建适配器的扩展类的string
  */
  private String createAdaptiveExtensionClassCode() {
        StringBuilder codeBuidler = new StringBuilder();
      // 获取这个类的所有方法 Method[] methods = type.getMethods(); boolean hasAdaptiveAnnotation = false; for(Method m : methods) {
        // 遍历方法,如果有方法上@Adaptive注解 if(m.isAnnotationPresent(Adaptive.class)) { hasAdaptiveAnnotation = true; break; } } // 完全没有Adaptive方法,则不需要生成Adaptive类 if(! hasAdaptiveAnnotation) throw new IllegalStateException("No adaptive method on extension " + type.getName() + ", refuse to create the adaptive class!"); codeBuidler.append("package " + type.getPackage().getName() + ";"); codeBuidler.append("\nimport " + ExtensionLoader.class.getName() + ";"); codeBuidler.append("\npublic class " + type.getSimpleName() + "$Adpative" + " implements " + type.getCanonicalName() + " {"); for (Method method : methods) { Class<?> rt = method.getReturnType(); Class<?>[] pts = method.getParameterTypes();//获取参数列表的类型 Class<?>[] ets = method.getExceptionTypes();//异常列表的类型         // 获得Adaptive的注解 Adaptive adaptiveAnnotation = method.getAnnotation(Adaptive.class); StringBuilder code = new StringBuilder(512);
        // 如果这个方法没有注解,添加不支持调用此方法的异常 if (adaptiveAnnotation == null) { code.append("throw new UnsupportedOperationException(\"method ") .append(method.toString()).append(" of interface ") .append(type.getName()).append(" is not adaptive method!\");"); } else { int urlTypeIndex = -1;
          // 寻找列表中类型是URL.class,记录它的位置,数据放到urlTypeIndex中 for (int i = 0; i < pts.length; ++i) { if (pts[i].equals(URL.class)) { urlTypeIndex = i; break; } } // 有类型为URL的参数 if (urlTypeIndex != -1) { // Null Point check String s = String.format("\nif (arg%d == null) throw new IllegalArgumentException(\"url == null\");", urlTypeIndex); code.append(s); s = String.format("\n%s url = arg%d;", URL.class.getName(), urlTypeIndex); code.append(s); } // 参数没有URL类型 else { String attribMethod = null; // 找到参数的URL属性 LBL_PTS: for (int i = 0; i < pts.length; ++i) { Method[] ms = pts[i].getMethods(); for (Method m : ms) { String name = m.getName(); if ((name.startsWith("get") || name.length() > 3) && Modifier.isPublic(m.getModifiers()) && !Modifier.isStatic(m.getModifiers()) && m.getParameterTypes().length == 0 && m.getReturnType() == URL.class) { urlTypeIndex = i; attribMethod = name; break LBL_PTS; } } } if(attribMethod == null) { throw new IllegalStateException("fail to create adative class for interface " + type.getName() + ": not found url parameter or url attribute in parameters of method " + method.getName()); } // Null point check String s = String.format("\nif (arg%d == null) throw new IllegalArgumentException(\"%s argument == null\");", urlTypeIndex, pts[urlTypeIndex].getName()); code.append(s); s = String.format("\nif (arg%d.%s() == null) throw new IllegalArgumentException(\"%s argument %s() == null\");", urlTypeIndex, attribMethod, pts[urlTypeIndex].getName(), attribMethod); code.append(s); s = String.format("%s url = arg%d.%s();",URL.class.getName(), urlTypeIndex, attribMethod); code.append(s); } // 获取Adaptive设置的value String[] value = adaptiveAnnotation.value(); // 没有设置Key,则使用“扩展点接口名的点分隔 作为Key if(value.length == 0) { char[] charArray = type.getSimpleName().toCharArray(); StringBuilder sb = new StringBuilder(128); for (int i = 0; i < charArray.length; i++) { if(Character.isUpperCase(charArray[i])) { if(i != 0) { sb.append("."); } sb.append(Character.toLowerCase(charArray[i])); } else { sb.append(charArray[i]); } } value = new String[] {sb.toString()}; } boolean hasInvocation = false;
          // 如果参数列表中有Invocation的实例 for (int i = 0; i < pts.length; ++i) { if (pts[i].getName().equals("com.alibaba.dubbo.rpc.Invocation")) { // Null Point check String s = String.format("\nif (arg%d == null) throw new IllegalArgumentException(\"invocation == null\");", i); code.append(s); s = String.format("\nString methodName = arg%d.getMethodName();", i); code.append(s); hasInvocation = true; break; } } // defaultExtName位注解中的value String defaultExtName = cachedDefaultName; String getNameCode = null; for (int i = value.length - 1; i >= 0; --i) { if(i == value.length - 1) { if(null != defaultExtName) { if(!"protocol".equals(value[i])) if (hasInvocation) getNameCode = String.format("url.getMethodParameter(methodName, \"%s\", \"%s\")", value[i], defaultExtName); else getNameCode = String.format("url.getParameter(\"%s\", \"%s\")", value[i], defaultExtName); else getNameCode = String.format("( url.getProtocol() == null ? \"%s\" : url.getProtocol() )", defaultExtName); } else { if(!"protocol".equals(value[i])) if (hasInvocation) getNameCode = String.format("url.getMethodParameter(methodName, \"%s\", \"%s\")", value[i], defaultExtName); else getNameCode = String.format("url.getParameter(\"%s\")", value[i]); else getNameCode = "url.getProtocol()"; } } else { if(!"protocol".equals(value[i])) if (hasInvocation) getNameCode = String.format("url.getMethodParameter(methodName, \"%s\", \"%s\")", value[i], defaultExtName); else getNameCode = String.format("url.getParameter(\"%s\", %s)", value[i], getNameCode); else getNameCode = String.format("url.getProtocol() == null ? (%s) : url.getProtocol()", getNameCode); } } code.append("\nString extName = ").append(getNameCode).append(";"); // check extName == null? String s = String.format("\nif(extName == null) " + "throw new IllegalStateException(\"Fail to get extension(%s) name from url(\" + url.toString() + \") use keys(%s)\");", type.getName(), Arrays.toString(value)); code.append(s); s = String.format("\n%s extension = (%<s)%s.getExtensionLoader(%s.class).getExtension(extName);", type.getName(), ExtensionLoader.class.getSimpleName(), type.getName()); code.append(s); // return statement if (!rt.equals(void.class)) { code.append("\nreturn "); } s = String.format("extension.%s(", method.getName()); code.append(s); for (int i = 0; i < pts.length; i++) { if (i != 0) code.append(", "); code.append("arg").append(i); } code.append(");"); } codeBuidler.append("\npublic " + rt.getCanonicalName() + " " + method.getName() + "("); for (int i = 0; i < pts.length; i ++) { if (i > 0) { codeBuidler.append(", "); } codeBuidler.append(pts[i].getCanonicalName()); codeBuidler.append(" "); codeBuidler.append("arg" + i); } codeBuidler.append(")"); if (ets.length > 0) { codeBuidler.append(" throws "); for (int i = 0; i < ets.length; i ++) { if (i > 0) { codeBuidler.append(", "); } codeBuidler.append(pts[i].getCanonicalName()); } } codeBuidler.append(" {"); codeBuidler.append(code.toString()); codeBuidler.append("\n}"); } codeBuidler.append("\n}"); if (logger.isDebugEnabled()) { logger.debug(codeBuidler.toString()); } return codeBuidler.toString(); }

   首先寻找这个类中所有的方法,查看方法中有没有打@Adaptive注解的,一个没有,直接报错,对于哪些没有加@Adaptive的方法,直接在要创建的Adaptive类上添加此方法不支持操作的异常。在方法中的注解上可以添加value值,如果填写了,使用此值,没有添加将更具类名创建的值作为value值。

public class AdaptiveExt2$Adpative implements shuqi.dubbotest.spi.adaptive.AdaptiveExt2 {
    public java.lang.String echo(java.lang.String arg0, com.alibaba.dubbo.common.URL arg1) {
        if (arg1 == null) throw new IllegalArgumentException("url == null");
        com.alibaba.dubbo.common.URL url = arg1;
        String extName = url.getParameter("t", "dubbo");
        if (extName == null)
            throw new IllegalStateException("Fail to get extension(shuqi.dubbotest.spi.adaptive.AdaptiveExt2) name from url(" + url.toString() + ") use keys([t])");
        shuqi.dubbotest.spi.adaptive.AdaptiveExt2 extension = (shuqi.dubbotest.spi.adaptive.AdaptiveExt2) ExtensionLoader.getExtensionLoader(shuqi.dubbotest.spi.adaptive.AdaptiveExt2.class).getExtension(extName);
        return extension.echo(arg0, arg1);
    }
}

  

  

 

  

 

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转载自www.cnblogs.com/huan30/p/12769683.html
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