链式编程概述
链式编程可以使得代码可读性高，同时也减少了代码量，变得优雅,简约。
//我们经常使用的StringBuffer 就是通过链式编程实现的
StringBuffer builder = new StringBuffer();
builder.append("aaa").append("bbb").append("ccc").append("dddd");
在Setter方法中实现
原理就是返回一个this对象，就是返回本身，达到链式效果。
(1)实体类:
import java.io.Serializable;
public class User implements Serializable {
private Integer id;
private String userName;
private String password;
private String nikeName;
private String email;
private String phoneNum;
public User() {
}
public User(Integer id, String userName, String password, String nikeName, String email, String phoneNum) {
this.id = id;
this.userName = userName;
this.password = password;
this.nikeName = nikeName;
this.email = email;
this.phoneNum = phoneNum;
}
public Integer getId() {
return id;
}
public User setId(Integer id) {
this.id = id;
return this;
}
public String getUserName() {
return userName;
}
public User setUserName(String userName) {
this.userName = userName;
return this;
}
public String getPassword() {
return password;
}
public User setPassword(String password) {
this.password = password;
return this;
}
public String getNikeName() {
return nikeName;
}
public User setNikeName(String nikeName) {
this.nikeName = nikeName;
return this;
}
public String getEmail() {
return email;
}
public User setEmail(String email) {
this.email = email;
return this;
}
public String getPhoneNum() {
return phoneNum;
}
public User setPhoneNum(String phoneNum) {
this.phoneNum = phoneNum;
return this;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", userName='" + userName + '\'' +
", password='" + password + '\'' +
", nikeName='" + nikeName + '\'' +
", email='" + email + '\'' +
", phoneNum='" + phoneNum + '\'' +
'}';
}
}
(2) 测试
public class Test {
public static void main(String[] args) {
User user = new User();
user.setId(2).setNikeName("李四").setPassword("123456").setEmail("xxxx");
System.out.println(user.toString());
}
}
(3)结果
Lombok实现
Lombok实现普通链式编程
使用Lombok之前，必须确保你的IDEA或者Eclipse中安装了lombok插件(可去IDEA插件市场去装)
<!-- 引入lombok的依赖 -->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.16.18</version>
</dependency>
(1)实体类：在实体类上添加@Accessors(chain = true)注解即可开启链式编程
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.experimental.Accessors;
import java.io.Serializable;
@Accessors(chain = true)
@Data
@NoArgsConstructor
@AllArgsConstructor
public class User implements Serializable {
private Integer id;
private String userName;
private String password;
private String nikeName;
private String email;
private String phoneNum;
}
(2)测试
public class Test {
public static void main(String[] args) {
User user = new User();
user.setId(1).setNikeName("张三").setPassword("123456").setEmail("xxxx");
System.out.println(user.toString());
}
}
(3)结果
Lombok实现静态链式编程
User中一些必输的字段需要，因此使用使用 lombok 将更改成如下写法： @RequiredArgsConstructor 和 @NonNull
(1).实体类
import lombok.Getter;
import lombok.NonNull;
import lombok.RequiredArgsConstructor;
import lombok.Setter;
import lombok.experimental.Accessors;
import java.io.Serializable;
@Accessors(chain = true)
@Getter
@Setter
@RequiredArgsConstructor(staticName = "of")
public class User implements Serializable {
@NonNull
private Integer id;
private String userName;
private String password;
private String nikeName;
private String email;
private String phoneNum;
@Override
public String toString() {
return "User{" +
"id=" + id +
", userName='" + userName + '\'' +
", password='" + password + '\'' +
", nikeName='" + nikeName + '\'' +
", email='" + email + '\'' +
", phoneNum='" + phoneNum + '\'' +
'}';
}
}
}
(2).测试
public class Test {
public static void main(String[] args) {
User user = User.of(3).setNikeName("李四").setPassword("123456").setEmail("xxxx");
System.out.println(user.toString());
}
}
(3)结果
builder模式的链式bean
build模式实现原理为在bean里面创建一个 静态builder方法 和一个 静态内部Builder类 ，通过调用静态builder方法来创建 Builder类，然后通过 builder类 中的 build方法直接创建一个Bean。
自定义 builder模式的链式Bean
(1)实体类
import java.io.Serializable;
public class User implements Serializable {
private Integer id;
private String userName;
private String password;
private String nikeName;
private String email;
private String phoneNum;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getNikeName() {
return nikeName;
}
public void setNikeName(String nikeName) {
this.nikeName = nikeName;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getPhoneNum() {
return phoneNum;
}
public void setPhoneNum(String phoneNum) {
this.phoneNum = phoneNum;
}
public static Builder builder() {
return new Builder();
}
public static class Builder{
private Integer id;
private String userName;
private String password;
private String nikeName;
private String email;
private String phoneNum;
public Builder id(int id) {
this.id = id;
return this;
}
public Builder userName(String userName) {
this.userName = userName;
return this;
}
public Builder password(String password) {
this.password = password;
return this;
}
public Builder nikeName(String nikeName) {
this.nikeName = nikeName;
return this;
}
public Builder email(String email) {
this.email = email;
return this;
}
public Builder phoneNum(String phoneNum) {
this.phoneNum = phoneNum;
return this;
}
public User build() {
User user = new User();
user.setId(id);
user.setUserName(userName);
user.setPassword(password);
user.setNikeName(nikeName);
user.setEmail(email);
user.setEmail(email);
user.setPhoneNum(phoneNum);
return user;
}
}
}
(2)测试
public class Test {
public static void main(String[] args) {
User user = User.builder().id(7).userName("szh").email("11111").build();
System.out.println(user.toString());
}
}
(3)结果
lombok 实现 builder模式的链式bean
只要加入一个@Builder注解就可以了。
(1)实体类
import lombok.*;
import java.io.Serializable;
@Builder
public class User implements Serializable {
private Integer id;
private String userName;
private String password;
private String nikeName;
private String email;
private String phoneNum;
}
(2).测试
public class Test {
public static void main(String[] args) {
User user = User.builder().id(7).userName("szh").email("11111").build();
System.out.println(user.toString());
}
}
(3)结果
