stacktraceelements.java

Guice是轻量级的依赖注入框架。简而言之

/**
 * Copyright (C) 2006 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.inject.util;

import com.google.inject.spi.SourceProviders;
import static com.google.inject.util.ReferenceType.SOFT;
import static com.google.inject.util.ReferenceType.WEAK;
import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.Member;
import java.util.Map;

/**
 * Creates stack trace elements for members.
 *
 * @author [e-mail] (Bob Lee)
 */
public class StackTraceElements {

  static final Map<Class<?>, LineNumbers> lineNumbersCache
      = new ReferenceCache<Class<?>, LineNumbers>(WEAK, SOFT) {
    protected LineNumbers create(Class<?> key) {
      try {
        return new LineNumbers(key);
      }
      catch (IOException e) {
        throw new RuntimeException(e);
      }
    }
  };

  public static Object forMember(Member member) {
    if (member == null) {
      return SourceProviders.UNKNOWN_SOURCE;
    }

    Class declaringClass = member.getDeclaringClass();
    LineNumbers lineNumbers = lineNumbersCache.get(declaringClass);
    Integer lineNumber = lineNumbers.getLineNumber(member);
    String memberName
        = member instanceof Constructor ? "<init>" : member.getName();
    StackTraceElement element = new StackTraceElement(
      declaringClass.getName(), memberName, lineNumbers.getSource(),
        lineNumber == null ? lineNumbers.getFirstLine() : lineNumber);
    return element;
  }

  public static Object forType(Class<?> implementation) {
    LineNumbers lineNumbers = lineNumbersCache.get(implementation);
    return new StackTraceElement(
        implementation.getName(),
        "class",
        lineNumbers.getSource(),
        lineNumbers.getFirstLine());
  }
}