如何使用ModelInput类中的Joshua Bloch版本描述的Builder模式？

如何使用ModelInput类中的Joshua Bloch版本描述的Builder模式？

Builder构造函数必须具有必需的参数。因此，在您的情况下，如果userId，clientId和parameterMap是强制性的，则我们将得到以下内容：

public final class ModelInput {    private long userid;    private long clientid;    private long timeout = 500L;    private Preference pref;    private boolean debug;    private Map<String, String> parameterMap;    public ModelInput(Builder builder) {        this.userid = builder.userId;        this.clientid = builder.clientId;        this.pref = builder.preference;        this.parameterMap = builder.parameterMap;        this.timeout = builder.timeout;        this.debug = builder.debug;    }    public static class Builder {        private long userId;        private long clientId;        private Preference preference;        private boolean debug;        private Map<String, String> parameterMap;        public Builder(long userId, long clientId, Map<String, String> parameterMap) { this.userId = userId; this.clientId = clientId; this.parameterMap = parameterMap;        }        public Builder preference(Preference preference) { this.preference = preference; return this;        }        public Builder debug(boolean debug) { this.debug = debug; return this;        }        public Builder timeout(long timeout) { this.timeout = timeout; return this;        }        ...        public ModelInput build() { return ModelInput(this);        }    }    // ModelInput getters / setters}

这是如何使用构建器类的方法：

String paramMap = new HashMap<String, String>();paramMap.put("attribute", "segmentation");ModelInput.Builder builder = new ModelInput.Builder(109739281L, 20L, paramMap);builder.preference(Preference.SECONDARY).timeout(1000L).debug(true);ModelInput modelInput = builder.build();

希望这可以帮助 ：）