学习
Java
的小伙伴们都应该听说过
Java
四大名著。今天博主将与大家分享其中一本经典著作
《Effective Java》
中的一个实用知识点 —— 如何使用设计模式中的构建者模式（
Builder Pattern
）来优化具有大量参数的类的构造方法。
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@Data
@EqualsAndHashCode(callSuper = false)
public class UserDTO {
private static final long serialVersionUID = 1L;
private String id;
private String loginName;
private String password;
private String name;
private int age;
private String email;
private String phone;
public UserDTO(String id) {
this.id = id;
}
public UserDTO(String loginName, String password) {
this.loginName = loginName;
this.password = password;
}
public UserDTO(String id, String loginName, String password) {
this.id = id;
this.loginName = loginName;
this.password = password;
}
public UserDTO(String id, String loginName, String password, String email) {
this.id = id;
this.loginName = loginName;
this.password = password;
this.email = email;
}
public UserDTO(String id, String loginName, String password, String email, int age) {
this.id = id;
this.loginName = loginName;
this.password = password;
this.email = email;
this.age = age;
}
}
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public static void main(String[] args) {
UserDTO userDTO = new UserDTO("", "张三", "", "", 0, "", "1008611");
UserDTO userDTO1 = new UserDTO();
userDTO1.setLoginName("张三");
userDTO1.setPassword("1008611");
UserDTO userDTO2 = new UserDTO("1", "张三", "loginName", "zhangsan", 18, "[email protected]", "1008611");
UserDTO userDTO3 = new UserDTO();
userDTO3.setId("2");
userDTO3.setName("zhangsan");
userDTO3.setEmail("[email protected]");
userDTO3.setLoginName("password");
userDTO3.setAge(18);
userDTO3.setPhone("1008611");
}
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@Data
@EqualsAndHashCode(callSuper = false)
public class UserDTO implements Serializable {
private final static final long serialVersionUID = 1L;
private final String id;
private final String loginName;
private final String password;
private final String name;
private final int age;
private final String email;
private final String phone;
public static class Builder {
private final String id;
private String loginName;
private String password;
private String name;
private int age;
private String email;
private String phone;
}
}
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@Data
@EqualsAndHashCode(callSuper = false)
public class UserDTO implements Serializable {
private final static final long serialVersionUID = 1L;
private final String id;
private final String loginName;
private final String password;
private final String name;
private final int age;
private final String email;
private final String phone;
public static class Builder {
private final String id;
private String loginName;
private String password;
private String name;
private int age;
private String email;
private String phone;
public Builder(String id) {
this.id = id;
}
}
}
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@Data
@EqualsAndHashCode(callSuper = false)
public class UserDTO implements Serializable {
private static final long serialVersionUID = 1L;
private final String id;
private final String loginName;
private final String password;
private final String name;
private final int age;
private final String email;
private final String phone;
public static class Builder {
private final String id;
private String loginName;
private String password;
private String name;
private int age;
private String email;
private String phone;
public Builder(String id) {
this.id = id;
}
public Builder loginName(String val) {
loginName = val;
return this;
}
public Builder password(String val) {
password = val;
return this;
}
public Builder name(String val) {
name = val;
return this;
}
public Builder age(int val) {
age = val;
return this;
}
public Builder email(String val) {
email = val;
return this;
}
public Builder phone(String val) {
phone = val;
return this;
}
}
}
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@Data
@EqualsAndHashCode(callSuper = false)
public class UserDTO implements Serializable {
private static final long serialVersionUID = 1L;
private final String id;
private final String loginName;
private final String password;
private final String name;
private final int age;
private final String email;
private final String phone;
public static class Builder {
private final String id;
private String loginName;
private String password;
private String name;
private int age;
private String email;
private String phone;
public Builder(String id) {
this.id = id;
}
public Builder loginName(String val) {
loginName = val;
return this;
}
public Builder password(String val) {
password = val;
return this;
}
public Builder name(String val) {
name = val;
return this;
}
public Builder age(int val) {
age = val;
return this;
}
public Builder email(String val) {
email = val;
return this;
}
public Builder phone(String val) {
phone = val;
return this;
}
public UserDTO build() {
return new UserDTO(this);
}
}
}
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@Data
@EqualsAndHashCode(callSuper = false)
public class UserDTO implements Serializable {
private static final long serialVersionUID = 1L;
private final String id;
private final String loginName;
private final String password;
private final String name;
private final int age;
private final String email;
private final String phone;
private UserDTO(Builder builder) {
this.id = builder.id;
this.loginName = builder.loginName;
this.password = builder.password;
this.name = builder.name;
this.age = builder.age;
this.email = builder.email;
this.phone = builder.phone;
}
public static class Builder {
private final String id;
private String loginName;
private String password;
private String name;
private int age;
private String email;
private String phone;
public Builder(String id) {
this.id = id;
}
public Builder loginName(String val) {
loginName = val;
return this;
}
public Builder password(String val) {
password = val;
return this;
}
public Builder name(String val) {
name = val;
return this;
}
public Builder age(int val) {
age = val;
return this;
}
public Builder email(String val) {
email = val;
return this;
}
public Builder phone(String val) {
phone = val;
return this;
}
public UserDTO build() {
return new UserDTO(this);
}
}
}
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public static void main(String[] args) {
UserDTO userDTO = new UserDTO.Builder("123")
.loginName("zhangsan")
.name("张三")
.password("password")
.build();
}
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@Data
@Builder
@EqualsAndHashCode(callSuper = false)
public class UserDTO implements Serializable {
private static final long serialVersionUID = 1L;
private final String id;
private final String loginName;
private final String password;
private final String name;
private final int age;
private final String email;
private final String phone;
}
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public static void main(String[] args) {
UserDTO userDTO = UserDTO.builder()
.id("123")
.loginName("zhangsan")
.name("张三")
.password("password")
.build();
}
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@Data
@Builder(toBuilder = true)
@EqualsAndHashCode(callSuper = false)
public class UserDTO implements Serializable {
private static final long serialVersionUID = 1L;
private final String id;
private final String loginName;
private final String password;
private final String name;
private final int age;
private final String email;
private final String phone;
}
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public static void main(String[] args) {
UserDTO userDTO = UserDTO.builder()
.id("123")
.loginName("zhangsan")
.name("张三")
.password("password")
.build();
UserDTO newUserDTO = userDTO.toBuilder().name("李四盗号了").build();
}
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@Data
@Builder(toBuilder = true, builderMethodName = "myBuilder")
@EqualsAndHashCode(callSuper = false)
public class UserDTO implements Serializable {
private static final long serialVersionUID = 1L;
private final String id;
private final String loginName;
private final String password;
private final String name;
private final int age;
private final String email;
private final String phone;
}
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public static void main(String[] args) {
UserDTO userDTO = UserDTO.myBuilder()
.id("123")
.loginName("zhangsan")
.name("张三")
.password("password")
.build();
UserDTO newUserDTO = userDTO.toBuilder().name("李四盗号了").build();
}
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