一、使用lombok简化代码

lombok提供了很多注解,在编译时候生成java代码,代替了手工编写一些简单的代码,使程序员可以关注更重要的实现。

二、常用注解

以model为例

public class DataDemo {
private Integer id;
private String name;
private Date time;
}

一下是添加不同lombok注解的编译结果示例,编译结果很简单,不需要做什么说明,直接上代码:

@Getter / @Setter

public class GetterSetterDemo {
private Integer id;
private String name;
private Date time; public GetterSetterDemo() { } public Integer getId() { return this.id; } public String getName() { return this.name; } public Date getTime() { return this.time; } public void setId(Integer id) { this.id = id; } public void setName(String name) { this.name = name; } public void setTime(Date time) { this.time = time; }
}

@ToString

model上添加注解:@ToString(exclude = {"id"}, includeFieldNames = false)

public class ToStringDemo {
private Integer id;
private String name;
private Date time; public ToStringDemo() { } public String toString() {
return "ToStringDemo(" + this.name + ", " + this.time + ")";
}
}

@Data

@Data 注解相当于 Getter + Setter + ToString + @RequiredArgsConstrutor,可以用在pojo上

public class DataDemo {
private Integer id;
private String name;
private Date time; public DataDemo() { } public Integer getId() { return this.id;} public String getName() { return this.name; } public Date getTime() { return this.time; } public void setId(Integer id) { this.id = id; } public void setName(String name) { this.name = name; } public void setTime(Date time) { this.time = time; } public boolean equals(Object o) { ... } protected boolean canEqual(Object other) { ... } public int hashCode() { ... } public String toString() {
return "DataDemo(id=" + this.getId() + ", name=" + this.getName() + ", time=" + this.getTime() + ")";
}
}

@Builder

public class BuilderDemo {
private Integer id;
private String name;
private Date time; @ConstructorProperties({"id", "name", "time"})
BuilderDemo(Integer id, String name, Date time) {
this.id = id;
this.name = name;
this.time = time;
} public static BuilderDemo.BuilderDemoBuilder builder() {
return new BuilderDemo.BuilderDemoBuilder();
} public static class BuilderDemoBuilder {
private Integer id;
private String name;
private Date time; BuilderDemoBuilder() {
} public BuilderDemo.BuilderDemoBuilder id(Integer id) {
this.id = id;
return this;
} public BuilderDemo.BuilderDemoBuilder name(String name) {
this.name = name;
return this;
} public BuilderDemo.BuilderDemoBuilder time(Date time) {
this.time = time;
return this;
} public BuilderDemo build() {
return new BuilderDemo(this.id, this.name, this.time);
} public String toString() {
return "BuilderDemo.BuilderDemoBuilder(id=" + this.id + ", name=" + this.name + ", time=" + this.time + ")";
}
}
}

构造函数

@AllArgsConstructor    全部参数构造函数

@NoArgsConstructor   无参数构造函数

@RequiredArgsConstructor   NoNull参数和常量构造函数

/**@AllArgsConstructor*/
public class AllArgsConstructorDemo {
private Integer id;
private String name;
private Date time; @ConstructorProperties({"id", "name", "time"})
public AllArgsConstructorDemo(Integer id, String name, Date time) {
this.id = id;
this.name = name;
this.time = time;
}
} /**@NoArgsConstructor*/
public class NoArgsConstructorDemo {
private Integer id;
private String name;
private Date time; public NoArgsConstructorDemo() { }
} /**@RequiredArgsConstructor(staticName = "of")*/
public class RequiredArgsConstructorDemo {
private Integer id;
private String name;
private Date time; private RequiredArgsConstructorDemo() { } public static RequiredArgsConstructorDemo of() {
return new RequiredArgsConstructorDemo();
}
} /**@RequiredArgsConstructor(staticName = "of")*/
public class RequiredArgsConstructorDemo {
private Integer id;
@NonNull
private String name;
@NonNull
private Date time; @ConstructorProperties({"name", "time"})
private RequiredArgsConstructorDemo(@NonNull String name, @NonNull Date time) {
if(name == null) {
throw new NullPointerException("name");
} else if(time == null) {
throw new NullPointerException("time");
} else {
this.name = name;
this.time = time;
}
} public static RequiredArgsConstructorDemo of(@NonNull String name, @NonNull Date time) {
return new RequiredArgsConstructorDemo(name, time);
}
}

@Value

public final class ValueDemo {
private final Integer id;
private final String name;
private final Date time; @ConstructorProperties({"id", "name", "time"})
public ValueDemo(Integer id, String name, Date time) {
this.id = id;
this.name = name;
this.time = time;
} public Integer getId() {
return this.id;
} public String getName() {
return this.name;
} public Date getTime() {
return this.time;
} public boolean equals(Object o) { ... } public int hashCode() { ... } public String toString() {
return "ValueDemo(id=" + this.getId() + ", name=" + this.getName() + ", time=" + this.getTime() + ")";
}
}

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