设计模式课程 设计模式精讲 7-3 建造者模式源码解析（jdk+guava+spring+mybaties）

1　　　　源码解析

1.1　　jdk解析

1.2　　guava解析

1.3　　spring解析

1.4　　mybaties解析

1　　　　源码解析

1.1　　jdk解析

String

 public StringBuilder append(boolean b) {
        super.append(b);
        return this;
    }

    public StringBuilder append(char c) {
        super.append(c);
        return this;
    }

    public StringBuilder append(int i) {
        super.append(i);
        return this;
    }

    public StringBuilder append(long lng) {
        super.append(lng);
        return this;
    }

    public StringBuilder append(float f) {
        super.append(f);
        return this;
    }

    public StringBuilder append(double d) {
        super.append(d);
        return this;
    }

StringBuilder

    public synchronized StringBuffer append(Object obj) {
        super.append(String.valueOf(obj));
        return this;
    }

    public synchronized StringBuffer append(String str) {
        super.append(str);
        return this;
    }

1.2　　guava解析（ImmutableSet）

 copyOf方法

 public static <E> ImmutableSet<E> copyOf(Collection<? extends E> elements) {
        if (elements instanceof ImmutableSet && !(elements instanceof ImmutableSortedSet)) {
            ImmutableSet<E> set = (ImmutableSet)elements;
            if (!set.isPartialView()) {
                return set;
            }
        } else if (elements instanceof EnumSet) {
            return copyOfEnumSet((EnumSet)elements);
        }

        Object[] array = elements.toArray();
        return construct(array.length, array);
    }

Of方法

 public static <E> ImmutableSet<E> of() {
        return RegularImmutableSet.EMPTY;
    }

    public static <E> ImmutableSet<E> of(E element) {
        return new SingletonImmutableSet(element);
    }

    public static <E> ImmutableSet<E> of(E e1, E e2) {
        return construct(2, e1, e2);
    }

    public static <E> ImmutableSet<E> of(E e1, E e2, E e3) {
        return construct(3, e1, e2, e3);
    }

    public static <E> ImmutableSet<E> of(E e1, E e2, E e3, E e4) {
        return construct(4, e1, e2, e3, e4);
    }

    public static <E> ImmutableSet<E> of(E e1, E e2, E e3, E e4, E e5) {
        return construct(5, e1, e2, e3, e4, e5);
    }

add方法（注意静态内部类）

   @CanIgnoreReturnValue
        public ImmutableSet.Builder<E> add(E element) {
            super.add(element);
            return this;
        }

public static class Builder<E> extends ArrayBasedBuilder<E> {
        public Builder() {
            this(4);
        }

        Builder(int capacity) {
            super(capacity);
        }

        @CanIgnoreReturnValue
        public ImmutableSet.Builder<E> add(E element) {
            super.add(element);
            return this;
        }

        @CanIgnoreReturnValue
        public ImmutableSet.Builder<E> add(E... elements) {
            super.add(elements);
            return this;
        }

        @CanIgnoreReturnValue
        public ImmutableSet.Builder<E> addAll(Iterable<? extends E> elements) {
            super.addAll(elements);
            return this;
        }

        @CanIgnoreReturnValue
        public ImmutableSet.Builder<E> addAll(Iterator<? extends E> elements) {
            super.addAll(elements);
            return this;
        }

        public ImmutableSet<E> build() {
            ImmutableSet<E> result = ImmutableSet.construct(this.size, this.contents);
            this.size = result.size();
            return result;
        }
    

1.3　　spring解析

BeanDefinitionBuilder类

   public static BeanDefinitionBuilder genericBeanDefinition() {
        BeanDefinitionBuilder builder = new BeanDefinitionBuilder();
        builder.beanDefinition = new GenericBeanDefinition();
        return builder;
    }

1.4　　mybaties解析

SqlSessionFactoryBuilder类（建造者模式中再使用建造者）

解析xml过程

public SqlSessionFactory build(Reader reader, String environment, Properties properties) {
        SqlSessionFactory var5;
        try {
            XMLConfigBuilder parser = new XMLConfigBuilder(reader, environment, properties);
            var5 = this.build(parser.parse());
        } catch (Exception var14) {
            throw ExceptionFactory.wrapException("Error building SqlSession.", var14);
        } finally {
            ErrorContext.instance().reset();

            try {
                reader.close();
            } catch (IOException var13) {
                ;
            }

        }

        return var5;
    }

XMLConfigBuilder类

  public Configuration parse() {
    if (parsed) {
      throw new BuilderException("Each XMLConfigBuilder can only be used once.");
    }
    parsed = true;
    parseConfiguration(parser.evalNode("/configuration"));
    return configuration;
  }

  private void parseConfiguration(XNode root) {
    try {
      Properties settings = settingsAsPropertiess(root.evalNode("settings"));
      //issue #117 read properties first
      propertiesElement(root.evalNode("properties"));
      loadCustomVfs(settings);
      typeAliasesElement(root.evalNode("typeAliases"));
      pluginElement(root.evalNode("plugins"));
      objectFactoryElement(root.evalNode("objectFactory"));
      objectWrapperFactoryElement(root.evalNode("objectWrapperFactory"));
      reflectorFactoryElement(root.evalNode("reflectorFactory"));
      settingsElement(settings);
      // read it after objectFactory and objectWrapperFactory issue #631
      environmentsElement(root.evalNode("environments"));
      databaseIdProviderElement(root.evalNode("databaseIdProvider"));
      typeHandlerElement(root.evalNode("typeHandlers"));
      mapperElement(root.evalNode("mappers"));
    } catch (Exception e) {
      throw new BuilderException("Error parsing SQL Mapper Configuration. Cause: " + e, e);
    }
  }