lombok在IntelliJ IDEA下的使用

lombok是一款可以精减java代码、提升开发人员生产效率的辅助工具，利用注解在编译期自动生成setter/getter/toString()/constructor之类的代码。代码越少，意味着出bug的可能性越低。

官网地址：https://projectlombok.org/ 首页有一段几分钟的演示视频，看完就明白是怎么回事了。

先来二段对比代码：

这是用lombok后的java代码：

import lombok.*;
import lombok.extern.slf4j.Slf4j;
import java.io.ByteArrayInputStream;
import java.io.*;
import java.util.ArrayList;

@Data
@Slf4j
@AllArgsConstructor
public class Something {

private String name;
private final String country;
private final Object lockObj = new Object();

public void sayHello(@NonNull String target) {
String content = String.format("hello,%s", target);
System.out.println(content);
log.info(content);
}

public void addBalabala() {
val list = new ArrayList<String>();
list.add("haha");
System.out.println(list.size());
}

@SneakyThrows(IOException.class)
public void closeBalabala() {
@Cleanup InputStream is = new ByteArrayInputStream("hello world".getBytes());
System.out.println(is.available());
}

@Synchronized("lockObj")
public void lockMethod() {
System.out.println("test lock method");
}
}

等效于下面这段java代码：

import java.beans.ConstructorProperties;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import lombok.NonNull;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Something {
private static final Logger log = LoggerFactory.getLogger(Something.class);
private String name;
private final String country;
private final Object lockObj = new Object();

public void sayHello(@NonNull String target) {
if(target == null) {
throw new NullPointerException("target");
} else {
String content = String.format("hello,%s", new Object[]{target});
System.out.println(content);
log.info(content);
}
}

public void addBalabala() {
ArrayList list = new ArrayList();
list.add("haha");
System.out.println(list.size());
}

public void closeBalabala() {
try {
ByteArrayInputStream $ex = new ByteArrayInputStream("hello world".getBytes());

try {
System.out.println($ex.available());
} finally {
if(Collections.singletonList($ex).get(0) != null) {
$ex.close();
}

}

} catch (IOException var6) {
throw var6;
}
}

public void lockMethod() {
Object var1 = this.lockObj;
synchronized(this.lockObj) {
System.out.println("test lock method");
}
}

public String getName() {
return this.name;
}

public String getCountry() {
return this.country;
}

public Object getLockObj() {
return this.lockObj;
}

public void setName(String name) {
this.name = name;
}

public boolean equals(Object o) {
if(o == this) {
return true;
} else if(!(o instanceof Something)) {
return false;
} else {
Something other = (Something)o;
if(!other.canEqual(this)) {
return false;
} else {
label47: {
String this$name = this.getName();
String other$name = other.getName();
if(this$name == null) {
if(other$name == null) {
break label47;
}
} else if(this$name.equals(other$name)) {
break label47;
}

return false;
}

String this$country = this.getCountry();
String other$country = other.getCountry();
if(this$country == null) {
if(other$country != null) {
return false;
}
} else if(!this$country.equals(other$country)) {
return false;
}

Object this$lockObj = this.getLockObj();
Object other$lockObj = other.getLockObj();
if(this$lockObj == null) {
if(other$lockObj != null) {
return false;
}
} else if(!this$lockObj.equals(other$lockObj)) {
return false;
}

return true;
}
}
}

protected boolean canEqual(Object other) {
return other instanceof Something;
}

public int hashCode() {
boolean PRIME = true;
byte result = 1;
String $name = this.getName();
int result1 = result * 59 + ($name == null?0:$name.hashCode());
String $country = this.getCountry();
result1 = result1 * 59 + ($country == null?0:$country.hashCode());
Object $lockObj = this.getLockObj();
result1 = result1 * 59 + ($lockObj == null?0:$lockObj.hashCode());
return result1;
}

public String toString() {
return "Something(name=" + this.getName() + ", country=" + this.getCountry() + ", lockObj=" + this.getLockObj() + ")";
}

@ConstructorProperties({"name", "country"})
public Something(String name, String country) {
this.name = name;
this.country = country;
}
}

大概减少了2/3的代码，各种注解的详细用法，请参考：https://projectlombok.org/features/index.html

IDEA下使用时，可以通过插件的形式安装，插件下载地址：https://github.com/mplushnikov/lombok-intellij-plugin/releases

然后

Plugins -> Install plugin from disk... 选择下载的zip包安装，重启idea即可。

另外，还有一个关键设置：



为了让设置生效，建议再重启一次idea，然后就可以开心的编码了，可以ide里可以直接看到生成的方法：（下图中打红圈的都是自动生成的）