设计学习-2

最直观的构建者，很多框架都这么用，为什么？因为参数太多，直接（*，*，*）的话容易搞混，而且默认值放在外面很乱

reader = new ReliableSpoolingFileEventReader.Builder()
          .spoolDirectory(directory)
          .completedSuffix(completedSuffix)
          .includePattern(includePattern)
          .ignorePattern(ignorePattern)
          .trackerDirPath(trackerDirPath)
          .annotateFileName(fileHeader)
          .fileNameHeader(fileHeaderKey)
          .annotateBaseName(basenameHeader)
          .baseNameHeader(basenameHeaderKey)
          .deserializerType(deserializerType)
          .deserializerContext(deserializerContext)
          .deletePolicy(deletePolicy)
          .inputCharset(inputCharset)
          .decodeErrorPolicy(decodeErrorPolicy)
          .consumeOrder(consumeOrder)
          .recursiveDirectorySearch(recursiveDirectorySearch)
          .build();

里面的实现很简单，给了默认值和设置方法，最后构建还是把前面的各种参数用构造器构造出来

    private File spoolDirectory;
    private String completedSuffix =
        SpoolDirectorySourceConfigurationConstants.SPOOLED_FILE_SUFFIX;
    private String includePattern = 
        SpoolDirectorySourceConfigurationConstants.DEFAULT_INCLUDE_PAT;
    private String ignorePattern =
        SpoolDirectorySourceConfigurationConstants.DEFAULT_IGNORE_PAT;
    private String trackerDirPath =
        SpoolDirectorySourceConfigurationConstants.DEFAULT_TRACKER_DIR;
    private Boolean annotateFileName =
        SpoolDirectorySourceConfigurationConstants.DEFAULT_FILE_HEADER;
    private String fileNameHeader =
        SpoolDirectorySourceConfigurationConstants.DEFAULT_FILENAME_HEADER_KEY;
    private Boolean annotateBaseName =
        SpoolDirectorySourceConfigurationConstants.DEFAULT_BASENAME_HEADER;
    private String baseNameHeader =
        SpoolDirectorySourceConfigurationConstants.DEFAULT_BASENAME_HEADER_KEY;
    private String deserializerType =
        SpoolDirectorySourceConfigurationConstants.DEFAULT_DESERIALIZER;
    private Context deserializerContext = new Context();
    private String deletePolicy =
        SpoolDirectorySourceConfigurationConstants.DEFAULT_DELETE_POLICY;
    private String inputCharset =
        SpoolDirectorySourceConfigurationConstants.DEFAULT_INPUT_CHARSET;
    private DecodeErrorPolicy decodeErrorPolicy = DecodeErrorPolicy.valueOf(
        SpoolDirectorySourceConfigurationConstants.DEFAULT_DECODE_ERROR_POLICY
            .toUpperCase(Locale.ENGLISH));
    private ConsumeOrder consumeOrder =
        SpoolDirectorySourceConfigurationConstants.DEFAULT_CONSUME_ORDER;
    private boolean recursiveDirectorySearch =
        SpoolDirectorySourceConfigurationConstants.DEFAULT_RECURSIVE_DIRECTORY_SEARCH;

    public Builder spoolDirectory(File directory) {
      this.spoolDirectory = directory;
      return this;
    }

    public Builder completedSuffix(String completedSuffix) {
      this.completedSuffix = completedSuffix;
      return this;
    }

    public Builder includePattern(String includePattern) {
      this.includePattern = includePattern;
      return this;
    }

    public Builder ignorePattern(String ignorePattern) {
      this.ignorePattern = ignorePattern;
      return this;
    }

    public Builder trackerDirPath(String trackerDirPath) {
      this.trackerDirPath = trackerDirPath;
      return this;
    }

    public Builder annotateFileName(Boolean annotateFileName) {
      this.annotateFileName = annotateFileName;
      return this;
    }

    public Builder fileNameHeader(String fileNameHeader) {
      this.fileNameHeader = fileNameHeader;
      return this;
    }

    public Builder annotateBaseName(Boolean annotateBaseName) {
      this.annotateBaseName = annotateBaseName;
      return this;
    }

    public Builder baseNameHeader(String baseNameHeader) {
      this.baseNameHeader = baseNameHeader;
      return this;
    }

    public Builder deserializerType(String deserializerType) {
      this.deserializerType = deserializerType;
      return this;
    }

    public Builder deserializerContext(Context deserializerContext) {
      this.deserializerContext = deserializerContext;
      return this;
    }

    public Builder deletePolicy(String deletePolicy) {
      this.deletePolicy = deletePolicy;
      return this;
    }

    public Builder inputCharset(String inputCharset) {
      this.inputCharset = inputCharset;
      return this;
    }

    public Builder recursiveDirectorySearch(boolean recursiveDirectorySearch) {
      this.recursiveDirectorySearch = recursiveDirectorySearch;
      return this;
    }

    public Builder decodeErrorPolicy(DecodeErrorPolicy decodeErrorPolicy) {
      this.decodeErrorPolicy = decodeErrorPolicy;
      return this;
    }

    public Builder consumeOrder(ConsumeOrder consumeOrder) {
      this.consumeOrder = consumeOrder;
      return this;
    }

    public ReliableSpoolingFileEventReader build() throws IOException {
      return new ReliableSpoolingFileEventReader(spoolDirectory, completedSuffix,
          includePattern, ignorePattern, trackerDirPath, annotateFileName, fileNameHeader,
          annotateBaseName, baseNameHeader, deserializerType,
          deserializerContext, deletePolicy, inputCharset, decodeErrorPolicy,
          consumeOrder, recursiveDirectorySearch);
    }