github.com/keysonZZZ/kmg@v0.0.0-20151121023212-05317bfd7d39/kmgRpc/kmgRpcJava/java/src/com/google/gson/internal/Primitives.java (about)

     1  /*
     2   * Copyright (C) 2008 Google Inc.
     3   *
     4   * Licensed under the Apache License, Version 2.0 (the "License");
     5   * you may not use this file except in compliance with the License.
     6   * You may obtain a copy of the License at
     7   *
     8   * http://www.apache.org/licenses/LICENSE-2.0
     9   *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   */
    16  
    17  package com.google.gson.internal;
    18  
    19  
    20  import java.lang.reflect.Type;
    21  import java.util.Collections;
    22  import java.util.HashMap;
    23  import java.util.Map;
    24  
    25  /**
    26   * Contains static utility methods pertaining to primitive types and their
    27   * corresponding wrapper types.
    28   *
    29   * @author Kevin Bourrillion
    30   */
    31  public final class Primitives {
    32    private Primitives() {}
    33  
    34    /** A map from primitive types to their corresponding wrapper types. */
    35    private static final Map<Class<?>, Class<?>> PRIMITIVE_TO_WRAPPER_TYPE;
    36  
    37    /** A map from wrapper types to their corresponding primitive types. */
    38    private static final Map<Class<?>, Class<?>> WRAPPER_TO_PRIMITIVE_TYPE;
    39  
    40    // Sad that we can't use a BiMap. :(
    41  
    42    static {
    43      Map<Class<?>, Class<?>> primToWrap = new HashMap<Class<?>, Class<?>>(16);
    44      Map<Class<?>, Class<?>> wrapToPrim = new HashMap<Class<?>, Class<?>>(16);
    45  
    46      add(primToWrap, wrapToPrim, boolean.class, Boolean.class);
    47      add(primToWrap, wrapToPrim, byte.class, Byte.class);
    48      add(primToWrap, wrapToPrim, char.class, Character.class);
    49      add(primToWrap, wrapToPrim, double.class, Double.class);
    50      add(primToWrap, wrapToPrim, float.class, Float.class);
    51      add(primToWrap, wrapToPrim, int.class, Integer.class);
    52      add(primToWrap, wrapToPrim, long.class, Long.class);
    53      add(primToWrap, wrapToPrim, short.class, Short.class);
    54      add(primToWrap, wrapToPrim, void.class, Void.class);
    55  
    56      PRIMITIVE_TO_WRAPPER_TYPE = Collections.unmodifiableMap(primToWrap);
    57      WRAPPER_TO_PRIMITIVE_TYPE = Collections.unmodifiableMap(wrapToPrim);
    58    }
    59  
    60    private static void add(Map<Class<?>, Class<?>> forward,
    61        Map<Class<?>, Class<?>> backward, Class<?> key, Class<?> value) {
    62      forward.put(key, value);
    63      backward.put(value, key);
    64    }
    65  
    66    /**
    67     * Returns true if this type is a primitive.
    68     */
    69    public static boolean isPrimitive(Type type) {
    70      return PRIMITIVE_TO_WRAPPER_TYPE.containsKey(type);
    71    }
    72  
    73    /**
    74     * Returns {@code true} if {@code type} is one of the nine
    75     * primitive-wrapper types, such as {@link Integer}.
    76     *
    77     * @see Class#isPrimitive
    78     */
    79    public static boolean isWrapperType(Type type) {
    80      return WRAPPER_TO_PRIMITIVE_TYPE.containsKey(
    81          $Gson$Preconditions.checkNotNull(type));
    82    }
    83  
    84    /**
    85     * Returns the corresponding wrapper type of {@code type} if it is a primitive
    86     * type; otherwise returns {@code type} itself. Idempotent.
    87     * <pre>
    88     *     wrap(int.class) == Integer.class
    89     *     wrap(Integer.class) == Integer.class
    90     *     wrap(String.class) == String.class
    91     * </pre>
    92     */
    93    public static <T> Class<T> wrap(Class<T> type) {
    94      // cast is safe: long.class and Long.class are both of type Class<Long>
    95      @SuppressWarnings("unchecked")
    96      Class<T> wrapped = (Class<T>) PRIMITIVE_TO_WRAPPER_TYPE.get(
    97          $Gson$Preconditions.checkNotNull(type));
    98      return (wrapped == null) ? type : wrapped;
    99    }
   100  
   101    /**
   102     * Returns the corresponding primitive type of {@code type} if it is a
   103     * wrapper type; otherwise returns {@code type} itself. Idempotent.
   104     * <pre>
   105     *     unwrap(Integer.class) == int.class
   106     *     unwrap(int.class) == int.class
   107     *     unwrap(String.class) == String.class
   108     * </pre>
   109     */
   110    public static <T> Class<T> unwrap(Class<T> type) {
   111      // cast is safe: long.class and Long.class are both of type Class<Long>
   112      @SuppressWarnings("unchecked")
   113      Class<T> unwrapped = (Class<T>) WRAPPER_TO_PRIMITIVE_TYPE.get(
   114          $Gson$Preconditions.checkNotNull(type));
   115      return (unwrapped == null) ? type : unwrapped;
   116    }
   117  }