Java类的Builder应用以及使用@Data和@Builder高效应用Builder
⭐Java Builder模式:是Java设计模式之一,它属于对象创建型模式,是将一个复杂对象的构建与它的表示分离,使得同样的构建过程可以创建不同的表示。
结论一:使用lombok的@Data和@Builder注解构建Java类的Builder简洁高效,推荐实际应用。
结论二:手动编写Java类的Builder,能够全貌理解Builder模式,推荐试试。
结论三:Java类的Builder模式,最大好处就是构建对象时,可以灵活构建需要的属性。
目录
1.1普通Java类.
1.1.1普通Java对象
普通Java类,一般有属性、set、get、toString方法。
public class City01Response implements Serializable {
private boolean success;
private String msg;
private Long cityId;
private String cityName;
private String cityDescribe;
public City01Response() {
}
public boolean isSuccess() {
return success;
}
public void setSuccess(boolean success) {
this.success = success;
}
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
public Long getCityId() {
return cityId;
}
public void setCityId(Long cityId) {
this.cityId = cityId;
}
public String getCityName() {
return cityName;
}
public void setCityName(String cityName) {
this.cityName = cityName;
}
public String getCityDescribe() {
return cityDescribe;
}
public void setCityDescribe(String cityDescribe) {
this.cityDescribe = cityDescribe;
}
@Override
public String toString() {
return "City01Response(" + "success=" + success + ", msg=" + msg + ", cityId=" + cityId + ", cityName=" + cityName + ", cityDescribe=" + cityDescribe + ")";
}
}
1.2普通Java类使用@Data注解
1.2.1普通Java类
使用@Data注解后,普通Java类,只有属性。set、get、toString方法由@Data注解接管。使用方式等价。
@Data
public class City01Response implements Serializable {
private boolean success;
private String msg;
private Long cityId;
private String cityName;
private String cityDescribe;
}
1.3手动编写Java类的Builder(静态内部类)
1.3.1手动编写Java类的Builder
本例内部类使用静态类实现,build使用静态方法。
普通Java类:City02Response
(1)编写普通Java类:City02Response,一般有属性、set、get、toString方法。
(2)在普通Java类:City02Response中,编写一个内部类:City02ResponseBuilder。
(3)在普通Java类:City02Response中,实现一个builder方法,创建一个内部类City02ResponseBuilder的对象。
(4)在内部类:City02ResponseBuilder中,实现一个build方法,返回普通Java类:City02Response的对象。
(5)在内部类:City02ResponseBuilder中。为每个属性实现一个设置方法,并且返回City02ResponseBuilder对象本身,即返回this。
public class City02Response implements Serializable {
private boolean success;
private String msg;
private Long cityId;
private String cityName;
private String cityDescribe;
public static City02Response.City02ResponseBuilder builder() {
return new City02Response.City02ResponseBuilder();
}
public static City02Response getCityInfoSuccess(Long cityID, String cityName, String cityDescribe) {
return builder().success(true).msg("获取城市信息成功").cityId(cityID).cityName(cityName).cityDescribe(cityDescribe).build();
}
public static City02Response getCityInfoFail(Long cityID, String failMsg) {
return builder().success(false).msg(failMsg).cityId(cityID).build();
}
public City02Response() {
}
public City02Response(boolean success, String msg, Long cityId, String cityName, String cityDescribe) {
this.success = success;
this.msg = msg;
this.cityId = cityId;
this.cityName = cityName;
this.cityDescribe = cityDescribe;
}
@Override
public String toString() {
return "City02Response(" + "success=" + success + ", msg=" + msg + ", cityId=" + cityId + ", cityName=" + cityName + ", cityDescribe=" + cityDescribe + ")";
}
public boolean isSuccess() {
return success;
}
public void setSuccess(boolean success) {
this.success = success;
}
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
public Long getCityId() {
return cityId;
}
public void setCityId(Long cityId) {
this.cityId = cityId;
}
public String getCityName() {
return cityName;
}
public void setCityName(String cityName) {
this.cityName = cityName;
}
public String getCityDescribe() {
return cityDescribe;
}
public void setCityDescribe(String cityDescribe) {
this.cityDescribe = cityDescribe;
}
public static class City02ResponseBuilder {
private boolean success;
private String msg;
private Long cityId;
private String cityName;
private String cityDescribe;
City02ResponseBuilder() {
}
public City02Response build() {
return new City02Response(success, msg, cityId, cityName, cityDescribe);
}
public City02Response.City02ResponseBuilder success(final boolean success) {
this.success = success;
return this;
}
public City02Response.City02ResponseBuilder msg(final String msg) {
this.msg = msg;
return this;
}
public City02Response.City02ResponseBuilder cityId(final Long cityId) {
this.cityId = cityId;
return this;
}
public City02Response.City02ResponseBuilder cityName(final String cityName) {
this.cityName = cityName;
return this;
}
public City02Response.City02ResponseBuilder cityDescribe(final String cityDescribe) {
this.cityDescribe = cityDescribe;
return this;
}
@Override
public String toString() {
return "City02ResponseBuilder.City02Response(" + "success=" + success + ", msg=" + msg + ", cityId=" + cityId + ", cityName=" + cityName + ", cityDescribe=" + cityDescribe + ")";
}
}
}
1.3.2代码中的getCityInfoSuccess和getCityInfoFail是对builder封装使用
代码中的getCityInfoSuccess和getCityInfoFail是对builder封装应用。不是必须部分。
1.4使用lombok的@Data和@Builder注解构建Java对象的Builder
1.4.1使用@Data和@Builder注解
使用@Data和@Builder注解,简化代码,效果等价。需引入jar包。
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.24</version>
</dependency>
@Data
@Builder
public class City03Response implements Serializable {
private boolean success;
private String msg;
private Long cityId;
private String cityName;
private String cityDescribe;
public static City03Response getCityInfoSuccess(Long cityID, String cityName, String cityDescribe) {
return builder().success(true).msg("获取城市信息成功").cityId(cityID).cityName(cityName).cityDescribe(cityDescribe).build();
}
public static City03Response getCityInfoFail(Long cityID, String failMsg) {
return builder().success(false).msg(failMsg).cityId(cityID).build();
}
}
1.4.2代码中的getCityInfoSuccess和getCityInfoFail是对builder封装使用
代码中的getCityInfoSuccess和getCityInfoFail是对builder封装应用。不是必须部分。
1.5普通Jave类和Builder类分开
1.5.1普通Java类
public class City04Response {
private boolean success;
private String msg;
private Long cityId;
private String cityName;
private String cityDescribe;
public City04Response(boolean success, String msg, Long cityId, String cityName, String cityDescribe) {
this.success = success;
this.msg = msg;
this.cityId = cityId;
this.cityName = cityName;
this.cityDescribe = cityDescribe;
}
public boolean isSuccess() {
return success;
}
public void setSuccess(boolean success) {
this.success = success;
}
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
public Long getCityId() {
return cityId;
}
public void setCityId(Long cityId) {
this.cityId = cityId;
}
public String getCityName() {
return cityName;
}
public void setCityName(String cityName) {
this.cityName = cityName;
}
public String getCityDescribe() {
return cityDescribe;
}
public void setCityDescribe(String cityDescribe) {
this.cityDescribe = cityDescribe;
}
@Override
public String toString() {
return "City04Response(" + "success=" + success + ", msg=" + msg + ", cityId=" + cityId + ", cityName=" + cityName + ", cityDescribe=" + cityDescribe + ")";
}
}
1.5.2普通Java类的Builder类
public class City04ResponseBuilder implements Serializable {
private boolean success;
private String msg;
private Long cityId;
private String cityName;
private String cityDescribe;
public City04ResponseBuilder setSuccess(boolean success) {
this.success = success;
return this;
}
public City04ResponseBuilder setMsg(String msg) {
this.msg = msg;
return this;
}
public City04ResponseBuilder setCityId(Long cityId) {
this.cityId = cityId;
return this;
}
public City04ResponseBuilder setCityName(String cityName) {
this.cityName = cityName;
return this;
}
public City04ResponseBuilder setCityDescribe(String cityDescribe) {
this.cityDescribe = cityDescribe;
return this;
}
public City04Response build() {
return new City04Response(success, msg, cityId, cityName, cityDescribe);
}
}
1.6测试
public class UseBuildUtils {
public static void main(String[] args) {
City02Response city02Response;
System.out.println("原生的Builder的Java对象,City02Response的Builder使用:");
city02Response = City02Response.builder().success(true).msg("获取城市信息成功").cityId(20230328L).cityName("杭州").cityDescribe("杭州是一个互联网城市").build();
System.out.println("City02Response直接使用builder: " +city02Response.toString());
city02Response = City02Response.getCityInfoSuccess(20230328L, "杭州", "杭州是一个互联网城市");
System.out.println("City02Response获取成功: " +city02Response.toString());
city02Response = City02Response.getCityInfoFail(20230328L, "网络异常,无法获取信息");
System.out.println("City02Response获取失败: " +city02Response.toString());
City03Response city03Response;
System.out.println("基于注解@Data和@Builder的Java对象,city03Response的Builder使用:");
city03Response = City03Response.builder().success(true).msg("获取城市信息成功").cityId(20230328L).cityName("苏州").cityDescribe("工业城市").build();
System.out.println("city03Response直接使用builder: " +city03Response.toString());
city03Response = City03Response.getCityInfoSuccess(20230328L, "苏州", "工业城市");
System.out.println("city03Response获取成功: " +city03Response.toString());
city03Response = City03Response.getCityInfoFail(20230328L, "网络异常,无法获取信息");
System.out.println("city03Response获取失败: " +city03Response.toString());
System.out.println("普通Java类和Builder类分开场景的Builder使用:");
City04Response city04Response = new City04ResponseBuilder().setSuccess(true).setMsg("获取城市信息成功").setCityId(20230328L).setCityName("宁波").setCityDescribe("港口城市").build();
System.out.println("city04Response获取成功:"+city04Response.toString());
}
}
原生的Builder的Java对象,City02Response的Builder使用:
City02Response直接使用builder: City02Response(success=true, msg=获取城市信息成功, cityId=20230328, cityName=杭州, cityDescribe=杭州是一个互联网城市)
City02Response获取成功: City02Response(success=true, msg=获取城市信息成功, cityId=20230328, cityName=杭州, cityDescribe=杭州是一个互联网城市)
City02Response获取失败: City02Response(success=false, msg=网络异常,无法获取信息, cityId=20230328, cityName=null, cityDescribe=null)基于注解@Data和@Builder的Java对象,city03Response的Builder使用:
city03Response直接使用builder: City03Response(success=true, msg=获取城市信息成功, cityId=20230328, cityName=苏州, cityDescribe=工业城市)
city03Response获取成功: City03Response(success=true, msg=获取城市信息成功, cityId=20230328, cityName=苏州, cityDescribe=工业城市)
city03Response获取失败: City03Response(success=false, msg=网络异常,无法获取信息, cityId=20230328, cityName=null, cityDescribe=null)普通Java类和Builder类分开场景的Builder使用:
city04Response获取成功:City04Response(success=true, msg=获取城市信息成功, cityId=20230328, cityName=宁波, cityDescribe=港口城市)