這篇文章主要給大家介紹了關於利用Builder方式創建對象的相關資料,文中通過示例代碼介紹的非常詳細,對大家的學習或者工作具有一定的參考學習價值,需要的朋友們下面隨着小編來一起學習學習吧
前言
在創建對象需要初始化數據,數據參數不容易區別,可傳可不傳的時候,可以考慮使用Builder建造方法創建。每每當看到別人寫的用Bulder方式來調用,就覺得so cool,那就自己也來用Builder方式創建對象吧。
下面話不多說了,來一起看看詳細的介紹吧
現在要錄入一系列人員的基本信息的示例:
創建Person類
public class Person { private String name; private int age; private float height; private float weight; public Person(String name, int age, float height, float weight) { this.name = name; this.age = age; this.height = height; this.weight = weight; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public float getHeight() { return height; } public void setHeight(float height) { this.height = height; } public float getWeight() { return weight; } public void setWeight(float weight) { this.weight = weight; } }
那麼創建對象就是這樣,後面參數不容易看出表示的是什麼,可讀性不強
new Person("馮提莫",18,150,43); new Person("溫婉",17,164,48);
用Builder模式進行改造
創建一個Builder類,屬性和Person類一樣,加上SetXxx()方法
static class Builder{ private String name; private int age; private float height; private float weight; public void setName(String name) { this.name = name; } public void setAge(int age) { this.age = age; } public void setHeight(float height) { this.height = height; } public void setWeight(float weight) { this.weight = weight; } }
將Person的構造方法改爲傳入Builder對象,將Builder對象的屬性值都賦予Person對象
public Person(Builder builder){ this.name = builder.name; this.age = builder.age; this.height = builder.height; this.weight = builder.weight; }
改造Builder類,關鍵步驟是將各個set方法返回Builder類對象,這樣就能繼續愉快地連續調用set方法了,最後調用build()創建方法返回Person對象。
static class Builder{ private String name; private int age; private float height; private float weight; public Builder setName(String name) { this.name = name; return this; } public Builder setAge(int age) { this.age = age; return this; } public Builder setHeight(float height) { this.height = height; return this; } public Builder setWeight(float weight) { this.weight = weight; return this; } public Person build(){ return new Person(this); } }
將各個set方法的返回值類型改爲Builder,每次都返回builder對象,這樣才能將set方法實現連續的鏈式調用。
build()方法創建一個person對象,會調用Person的帶參構造方法,將builder對象的屬性依次賦予person對象。person中的屬性值就是鏈式調用set方法的各個值。
使用Builder模式創建Person對象,明顯看出代碼可讀性大大增強。注:Builder創建方式通常是在創建的對象少的情況下使用。
Person person = new Person.Builder() .setName("莉哥") .setAge(20) .setHeight(162) .setWeight(45) .build();
總結
以上就是這篇文章的全部內容了,希望本文的內容對大家的學習或者工作具有一定的參考學習價值,如果有疑問大家可以留言交流,謝謝大家對神馬文庫的支持。