原文地址:http://blog.csdn.net/v2sking/article/details/73431364
Lombok简介
Project Lombok makes java a spicier language by adding ‘handlers’ that know >how to build and compile simple, boilerplate-free, not-quite-java code.github上官方是这么描述lombok的: lombok项目通过增加处理程序使我们的java语言更加刺激(简洁和快速)。
先看个简单示例:
我们做java开发的时候,最不少写的就是javabean了,bean字段都需要添加gettter/setter方法,往往我们只能一次又一次的使用ide生成gettter,setter
构造器等等。
lombok是如何帮我们解决这种重复性劳动呢?
-
package com.lhy.boot.lombok;
-
-
import lombok.Getter;
-
import lombok.Setter;
-
-
@Getter
-
@Setter
-
public class GetterSetterExample1 {
-
-
private int age = 10;
-
-
private String name ="张三丰";
-
-
private boolean registerd;
-
-
private String sex;
-
-
}
编译后的class:
-
package com.lhy.boot.lombok;
-
-
public class GetterSetterExample1
-
{
-
private int age = 10;
-
-
private String name = "张三丰";
-
private boolean registerd;
-
private String sex;
-
-
public int getAge()
-
{
-
return this.age;
-
}
-
-
public String getName() {
-
return this.name;
-
}
-
-
public boolean isRegisterd() {
-
return this.registerd;
-
}
-
-
public String getSex() {
-
return this.sex;
-
}
-
-
public GetterSetterExample1 setAge(int age) {
-
this.age = age;
-
return this;
-
}
-
-
public GetterSetterExample1 setName(String name) {
-
this.name = name;
-
return this;
-
}
-
-
public GetterSetterExample1 setRegisterd(boolean registerd) {
-
this.registerd = registerd;
-
return this;
-
}
-
-
public GetterSetterExample1 setSex(String sex) {
-
this.sex = sex;
-
return this;
-
}
-
}
通过gettter,setter注解lombok已经帮我们自动生成了getter,setter方法!
是不是很神奇呢?lombok是怎么的做到的?这个后边再讲,先把lombok ide插件环境搭起来
下载并引用
-
<dependency>
-
<groupId>org.projectlombok</groupId>
-
<artifactId>lombok</artifactId>
-
<version>1.16.16</version>
-
</dependency>
或者到官网下载jar包 https://projectlombok.org/download
安装ide插件
myeclipse/eclipse
下载完成后 命令行运行
-
java -jar lombok-1.16.16.jar
弹出安装界面:
specify location 选择myeclipse安装目录,eclipse同理。
点击 install/update 安装完成。
或者将jar包放入myeclipse 根目录下
myeclipse.ini文件末尾添加:
-
-javaagent:lombok-1.16.16.jar
重启myeclipse即可。
安装完毕后
打开myeclipse about 可以看到
证明插件安装完成
IntelliJ IDEA
-
定位到 File > Settings > Plugins
-
点击 Browse repositories…
-
搜索 Lombok Plugin
-
点击 Install plugin
-
重启 IDEA
Lombok注解详解
全局配置文件
我们可以从项目根目录下新建一个lombok.config(当然目录不是固定的,lombok会搜索所有lombok.config文件)
在这个文件加入一行
config.stopBubbling = true
表示该文件目录为根目录,lombok将从该目录下开始搜索。
每个子目录都可以配置lombok.config 作用范围只在该目录下,并且覆盖父目录的配置。
Lombok通常为所有生成的节点生成注释,添加@javax.annotation.Generated 。
可以用:
lombok.addJavaxGeneratedAnnotation = false 设置取消
下面看下lombok提供了哪些有趣的注解。
使用Lombok ,java也能够像javascript一样使用弱类型定义变量了
val注解变量申明是final类型 var注解变量是非final类型
-
import java.util.ArrayList;
-
import java.util.HashMap;
-
import lombok.val;
-
-
public class ValExample {
-
public String example() {
-
val example = new ArrayList<String>();
-
example.add("Hello, World!");
-
val foo = example.get(0);
-
return foo.toLowerCase();
-
}
-
-
public void example2() {
-
val map = new HashMap<Integer, String>();
-
map.put(0, "zero");
-
map.put(5, "five");
-
for (val entry : map.entrySet()) {
-
System.out.printf("%d: %s\n", entry.getKey(), entry.getValue());
-
}
-
}
-
}
翻译后
-
import java.util.ArrayList;
-
import java.util.HashMap;
-
import java.util.Map;
-
-
public class ValExample {
-
public String example() {
-
final ArrayList<String> example = new ArrayList<String>();
-
example.add("Hello, World!");
-
final String foo = example.get(0);
-
return foo.toLowerCase();
-
}
-
-
public void example2() {
-
final HashMap<Integer, String> map = new HashMap<Integer, String>();
-
map.put(0, "zero");
-
map.put(5, "five");
-
for (final Map.Entry<Integer, String> entry : map.entrySet()) {
-
System.out.printf("%d: %s\n", entry.getKey(), entry.getValue());
-
}
-
}
-
}
[email protected]
在方法或构造函数的参数上使用@NonNull,lombok将生成一个空值检查语句。
-
import lombok.NonNull;
-
-
public class NonNullExample extends Something {
-
private String name;
-
-
public NonNullExample(@NonNull Person person) {
-
super("Hello");
-
this.name = person.getName();
-
}
-
}
翻译后
-
import lombok.NonNull;
-
-
public class NonNullExample extends Something {
-
private String name;
-
-
public NonNullExample(@NonNull Person person) {
-
super("Hello");
-
if (person == null) {
-
throw new NullPointerException("person");
-
}
-
this.name = person.getName();
-
}
-
}
[email protected]
使用该注解能够自动释放io资源
-
import lombok.Cleanup;
-
import java.io.*;
-
-
public class CleanupExample {
-
public static void main(String[] args) throws IOException {
-
@Cleanup InputStream in = new FileInputStream(args[0]);
-
@Cleanup OutputStream out = new FileOutputStream(args[1]);
-
byte[] b = new byte[10000];
-
while (true) {
-
int r = in.read(b);
-
if (r == -1) break;
-
out.write(b, 0, r);
-
}
-
}
-
}
翻译后
-
import java.io.*;
-
-
public class CleanupExample {
-
public static void main(String[] args) throws IOException {
-
InputStream in = new FileInputStream(args[0]);
-
try {
-
OutputStream out = new FileOutputStream(args[1]);
-
try {
-
byte[] b = new byte[10000];
-
while (true) {
-
int r = in.read(b);
-
if (r == -1) break;
-
out.write(b, 0, r);
-
}
-
} finally {
-
if (out != null) {
-
out.close();
-
}
-
}
-
} finally {
-
if (in != null) {
-
in.close();
-
}
-
}
-
}
-
}
当然从1.7开始jdk已经提供了try with resources的方式自动回收资源
-
static String readFirstLineFromFile(String path) throws IOException {
-
try (BufferedReader br = new BufferedReader(new FileReader(path))) {
-
return br.readLine();
-
}
-
}
-
import lombok.AccessLevel;
-
import lombok.Getter;
-
import lombok.Setter;
-
-
public class GetterSetterExample {
-
/**
-
* Age of the person. Water is wet.
-
*
-
* @param age New value for this person's age. Sky is blue.
-
* @return The current value of this person's age. Circles are round.
-
*/
-
@Getter @Setter private int age = 10;
-
-
/**
-
* Name of the person.
-
* -- SETTER --
-
* Changes the name of this person.
-
*
-
* @param name The new value.
-
*/
-
@Setter(AccessLevel.PROTECTED) private String name;
-
-
@Override public String toString() {
-
return String.format("%s (age: %d)", name, age);
-
}
-
}
翻译后
-
public class GetterSetterExample {
-
/**
-
* Age of the person. Water is wet.
-
*/
-
private int age = 10;
-
-
/**
-
* Name of the person.
-
*/
-
private String name;
-
-
@Override public String toString() {
-
return String.format("%s (age: %d)", name, age);
-
}
-
-
/**
-
* Age of the person. Water is wet.
-
*
-
* @return The current value of this person's age. Circles are round.
-
*/
-
public int getAge() {
-
return age;
-
}
-
-
/**
-
* Age of the person. Water is wet.
-
*
-
* @param age New value for this person's age. Sky is blue.
-
*/
-
public void setAge(int age) {
-
this.age = age;
-
}
-
-
/**
-
* Changes the name of this person.
-
*
-
* @param name The new value.
-
*/
-
protected void setName(String name) {
-
this.name = name;
-
}
-
}
扩展配置:lombok.accessors.chain
= [
true
|
false
]
(default: false)如果设置为true,生成的setter将返回this(而不是void),通过这个配置我们可以像jquery一样愉快的链式编程了。可以在类加增加一个@Accessors 注解 配置chain属性,优先于全局配置。
lombok.accessors.fluent
= [
true
|
false
]
(default: false)如果设置为true,生成的getter和setter将不会使用bean标准的get、is或set进行前缀;相反,方法将使用与字段相同的名称(减去前缀)。可以在类加增加一个@Accessors注解,配置fluent属性,优先于全局配置
lombok.accessors.prefix
+=
a field prefix (default:
empty list)
给getter/setter方法增加前缀 例如配置 +=M 原有的 getFoo方法将变为getMFoo方法。 lombok.getter.noIsPrefix
=
[
true
|
false
]
(default: false)
如果设置为true,那么boolean型字段生成的getter将使用get前缀而不是默认的is前缀
生成一个toString方法,log debug神器
默认的toString格式为:ClassName(fieldName= fieldValue ,fieldName1=fieldValue)
-
import lombok.ToString;
-
-
@ToString(exclude="id")
-
public class ToStringExample {
-
private static final int STATIC_VAR = 10;
-
private String name;
-
private Shape shape = new Square(5, 10);
-
private String[] tags;
-
private int id;
-
-
public String getName() {
-
return this.getName();
-
}
-
-
@ToString(callSuper=true, includeFieldNames=true)
-
public static class Square extends Shape {
-
private final int width, height;
-
-
public Square(int width, int height) {
-
this.width = width;
-
this.height = height;
-
}
-
}
-
}
翻译后
-
import java.util.Arrays;
-
-
ublic class ToStringExample {
-
private static final int STATIC_VAR = 10;
-
private String name;
-
private Shape shape = new Square(5, 10);
-
private String[] tags;
-
private int id;
-
-
public String getName() {
-
return this.getName();
-
}
-
-
public static class Square extends Shape {
-
private final int width, height;
-
-
public Square(int width, int height) {
-
this.width = width;
-
this.height = height;
-
}
-
-
@Override public String toString() {
-
return "Square(super=" + super.toString() + ", width=" + this.width + ", height=" + this.height + ")";
-
}
-
}
-
-
@Override public String toString() {
-
return "ToStringExample(" + this.getName() + ", " + this.shape + ", " + Arrays.deepToString(this.tags) + ")";
-
}
扩展配置:
lombok.toString.includeFieldNames
=
[true
| false
]
(default: true)
通常,lombok以fieldName=fieldValue的形式为每个字段生成一个toString响应的片段。如果设置为false,lombok将省略字段的名称,可以在该注解上配置属性includeFieldNames来标示包含的字段,这样可以覆盖默认配置。
lombok.toString.doNotUseGetters
=
[true
| false
]
(default: false)如果设置为true,lombok将直接访问字段,而不是在生成tostring方法时使用getter(如果可用)。可以在该注解上配置属性doNotUseGetters来标示不使用getter的字段,这样可以覆盖默认配置。
给类增加equals和hashCode方法
-
import lombok.EqualsAndHashCode;
-
-
@EqualsAndHashCode(exclude={"id", "shape"})
-
public class EqualsAndHashCodeExample {
-
private transient int transientVar = 10;
-
private String name;
-
private double score;
-
private Shape shape = new Square(5, 10);
-
private String[] tags;
-
private int id;
-
-
public String getName() {
-
return this.name;
-
}
-
-
@EqualsAndHashCode(callSuper=true)
-
public static class Square extends Shape {
-
private final int width, height;
-
-
public Square(int width, int height) {
-
this.width = width;
-
this.height = height;
-
}
-
}
-
}
翻译后
-
import java.util.Arrays;
-
-
ublic class EqualsAndHashCodeExample {
-
private transient int transientVar = 10;
-
private String name;
-
private double score;
-
private Shape shape = new Square(5, 10);
-
private String[] tags;
-
private int id;
-
-
public String getName() {
-
return this.name;
-
}
-
-
@Override public boolean equals(Object o) {
-
if (o == this) return true;
-
if (!(o instanceof EqualsAndHashCodeExample)) return false;
-
EqualsAndHashCodeExample other = (EqualsAndHashCodeExample) o;
-
if (!other.canEqual((Object)this)) return false;
-
if (this.getName() == null ? other.getName() != null : !this.getName().equals(other.getName())) return false;
-
if (Double.compare(this.score, other.score) != 0) return false;
-
if (!Arrays.deepEquals(this.tags, other.tags)) return false;
-
return true;
-
}
-
-
@Override public int hashCode() {
-
final int PRIME = 59;
-
int result = 1;
-
final long temp1 = Double.doubleToLongBits(this.score);
-
result = (result*PRIME) + (this.name == null ? 43 : this.name.hashCode());
-
result = (result*PRIME) + (int)(temp1 ^ (temp1 >>> 32));
-
result = (result*PRIME) + Arrays.deepHashCode(this.tags);
-
return result;
-
}
-
-
protected boolean canEqual(Object other) {
-
return other instanceof EqualsAndHashCodeExample;
-
}
-
-
public static class Square extends Shape {
-
private final int width, height;
-
-
public Square(int width, int height) {
-
this.width = width;
-
this.height = height;
-
}
-
-
@Override public boolean equals(Object o) {
-
if (o == this) return true;
-
if (!(o instanceof Square)) return false;
-
Square other = (Square) o;
-
if (!other.canEqual((Object)this)) return false;
-
if (!super.equals(o)) return false;
-
if (this.width != other.width) return false;
-
if (this.height != other.height) return false;
-
return true;
-
}
-
-
@Override public int hashCode() {
-
final int PRIME = 59;
-
int result = 1;
-
result = (result*PRIME) + super.hashCode();
-
result = (result*PRIME) + this.width;
-
result = (result*PRIME) + this.height;
-
return result;
-
}
-
-
protected boolean canEqual(Object other) {
-
return other instanceof Square;
-
}
-
}
扩展配置:
lombok.config增加:
lombok.equalsAndHashCode.doNotUseGetters
=
[true
| false
]
(default: false)如果设置为true,lombok将直接访问字段,而不是在生成equals和hashcode方法时使用getter(如果可用)。可以在该注解上配置属性donotusegetter来标示不使用getter的字段,这样可以覆盖默认配置。lombok.equalsAndHashCode.callSuper
=
[call
| skip
| warn
]
(default: warn)如果设置为call,lombok将生成对hashCode的超类实现的调用。如果设置为skip,则不会生成这样的调用。默认行为warn类似于skip,并带有附加警告。[email protected], @RequiredArgsConstructor and @AllArgsConstructor
给类增加无参构造器 指定参数的构造器 包含所有参数的构造器
-
import lombok.AccessLevel;
-
import lombok.RequiredArgsConstructor;
-
import lombok.AllArgsConstructor;
-
import lombok.NonNull;
-
-
@RequiredArgsConstructor(staticName = "of")
-
@AllArgsConstructor(access = AccessLevel.PROTECTED)
-
public class ConstructorExample<T> {
-
private int x, y;
-
@NonNull private T description;
-
-
@NoArgsConstructor
-
public static class NoArgsExample {
-
@NonNull private String field;
-
}
-
}
翻译后
-
public class ConstructorExample<T> {
-
private int x, y;
-
@NonNull private T description;
-
-
private ConstructorExample(T description) {
-
if (description == null) throw new NullPointerException("description");
-
this.description = description;
-
}
-
-
public static <T> ConstructorExample<T> of(T description) {
-
return new ConstructorExample<T>(description);
-
}
-
-
@java.beans.ConstructorProperties({"x", "y", "description"})
-
protected ConstructorExample(int x, int y, T description) {
-
if (description == null) throw new NullPointerException("description");
-
this.x = x;
-
this.y = y;
-
this.description = description;
-
}
-
-
public static class NoArgsExample {
-
@NonNull private String field;
-
-
public NoArgsExample() {
-
}
-
}
-
}
扩展配置:
lombok.anyConstructor.suppressConstructorProperties
=
[true
| false
]
(default: false
)如果将其设置为true,那么lombok将跳过添加一个@java.bean.ConstructorProperties生成的构造器。这在android和GWT开发中很有用,因为这些注释通常不可用。
[email protected]
包含以**解的集合
@ToString,@EqualsAndHashCode,所有字段的 @Getter 所有非final字段的@Setter ,@RequiredArgsConstructor
-
import lombok.AccessLevel;
-
import lombok.Setter;
-
import lombok.Data;
-
import lombok.ToString;
-
-
@Data public class DataExample {
-
private final String name;
-
@Setter(AccessLevel.PACKAGE) private int age;
-
private double score;
-
private String[] tags;
-
-
@ToString(includeFieldNames=true)
-
@Data(staticConstructor="of")
-
public static class Exercise<T> {
-
private final String name;
-
private final T value;
-
}
-
}
翻译后
[email protected]
@value是@data的不可变对象 (不可变对象的用处和创建:https://my.oschina.net/jasonultimate/blog/166810)
所有字段都是私有的,默认情况下是final的,并且不会生成setter。默认情况下,类本身也是final的,因为不可变性不能强制转化为子类。与@data一样,有用toString()、equals()和hashCode()方法也是生成的,每个字段都有一个getter方法,并且一个覆盖每个参数的构造器也会生成。
[email protected]
建筑者模式
是现在比较推崇的一种构建值对象的方式。
-
import lombok.Builder;
-
import lombok.Singular;
-
import java.util.Set;
-
-
@Builder
-
public class BuilderExample {
-
private String name;
-
private int age;
-
@Singular private Set<String> occupations;
-
}
翻译后
-
import java.util.Set;
-
-
public class BuilderExample {
-
private String name;
-
private int age;
-
private Set<String> occupations;
-
-
BuilderExample(String name, int age, Set<String> occupations) {
-
this.name = name;
-
this.age = age;
-
this.occupations = occupations;
-
}
-
-
public static BuilderExampleBuilder builder() {
-
return new BuilderExampleBuilder();
-
}
-
-
public static class BuilderExampleBuilder {
-
private String name;
-
private int age;
-
private java.util.ArrayList<String> occupations;
-
-
BuilderExampleBuilder() {
-
}
-
-
public BuilderExampleBuilder name(String name) {
-
this.name = name;
-
return this;
-
}
-
-
public BuilderExampleBuilder age(int age) {
-
this.age = age;
-
return this;
-
}
-
-
public BuilderExampleBuilder occupation(String occupation) {
-
if (this.occupations == null) {
-
this.occupations = new java.util.ArrayList<String>();
-
}
-
-
this.occupations.add(occupation);
-
return this;
-
}
-
-
public BuilderExampleBuilder occupations(Collection<? extends String> occupations) {
-
if (this.occupations == null) {
-
this.occupations = new java.util.ArrayList<String>();
-
}
-
-
this.occupations.addAll(occupations);
-
return this;
-
}
-
-
public BuilderExampleBuilder clearOccupations() {
-
if (this.occupations != null) {
-
this.occupations.clear();
-
}
-
-
return this;
-
}
-
-
public BuilderExample build() {
-
// complicated switch statement to produce a compact properly sized immutable set omitted.
-
// go to https://projectlombok.org/features/Singular-snippet.html to see it.
-
Set<String> occupations = ...;
-
return new BuilderExample(name, age, occupations);
-
}
-
-
@java.lang.Override
-
public String toString() {
-
return "BuilderExample.BuilderExampleBuilder(name = " + this.name + ", age = " + this.age + ", occupations = " + this.occupations + ")";
-
}
-
}
-
}
[email protected]
把checked异常转化为unchecked异常,好处是不用再往上层方法抛出了,美其名曰暗埋异常
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import lombok.SneakyThrows;
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public class SneakyThrowsExample implements Runnable {
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@SneakyThrows(UnsupportedEncodingException.class)
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public String utf8ToString(byte[] bytes) {
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return new String(bytes, "UTF-8");
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}
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@SneakyThrows
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public void run() {
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throw new Throwable();
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}
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}
翻译后:
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import lombok.Lombok;
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public class SneakyThrowsExample implements Runnable {
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public String utf8ToString(byte[] bytes) {
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try {
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return new String(bytes, "UTF-8");
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} catch (UnsupportedEncodingException e) {
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throw Lombok.sneakyThrow(e);
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}
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}
-
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public void run() {
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try {
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throw new Throwable();
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} catch (Throwable t) {
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throw Lombok.sneakyThrow(t);
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}
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}
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}
[email protected]
类似于Synchronized 关键字 但是可以隐藏同步锁
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import lombok.Synchronized;
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ublic class SynchronizedExample {
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private final Object readLock = new Object();
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@Synchronized
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public static void hello() {
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System.out.println("world");
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}
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@Synchronized
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public int answerToLife() {
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return 42;
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}
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@Synchronized("readLock")
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public void foo() {
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System.out.println("bar");
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}
翻译后
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public class SynchronizedExample {
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private static final Object $LOCK = new Object[0];
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private final Object $lock = new Object[0];
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private final Object readLock = new Object();
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public static void hello() {
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synchronized($LOCK) {
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System.out.println("world");
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}
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}
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public int answerToLife() {
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synchronized($lock) {
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return 42;
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}
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}
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public void foo() {
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synchronized(readLock) {
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System.out.println("bar");
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}
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}
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}
xianzjdk推荐使用Lock了,这个仅供参考
[email protected](lazy=true)
如果getter方法计算值需要大量CPU,或者值占用大量内存,第一次调用这个getter,它将一次计算一个值,然后从那时开始缓存它
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import lombok.Getter;
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public class GetterLazyExample {
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@Getter(lazy=true) private final double[] cached = expensive();
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private double[] expensive() {
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double[] result = new double[1000000];
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for (int i = 0; i < result.length; i++) {
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result[i] = Math.asin(i);
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}
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return result;
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}
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}
翻译后
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public class GetterLazyExample {
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private final java.util.concurrent.AtomicReference<java.lang.Object> cached = new java.util.concurrent.AtomicReference<java.lang.Object>();
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public double[] getCached() {
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java.lang.Object value = this.cached.get();
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if (value == null) {
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synchronized(this.cached) {
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value = this.cached.get();
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if (value == null) {
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final double[] actualValue = expensive();
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value = actualValue == null ? this.cached : actualValue;
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this.cached.set(value);
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}
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}
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}
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return (double[])(value == this.cached ? null : value);
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}
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private double[] expensive() {
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double[] result = new double[1000000];
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for (int i = 0; i < result.length; i++) {
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result[i] = Math.asin(i);
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}
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return result;
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}
[email protected]
可以生成各种log对象,方便多了
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import lombok.extern.java.Log;
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import lombok.extern.slf4j.Slf4j;
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@Log
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public class LogExample {
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public static void main(String... args) {
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log.error("Something's wrong here");
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}
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}
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@Slf4j
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public class LogExampleOther {
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public static void main(String... args) {
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log.error("Something else is wrong here");
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}
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}
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@CommonsLog(topic="CounterLog")
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public class LogExampleCategory {
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public static void main(String... args) {
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log.error("Calling the 'CounterLog' with a message");
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}
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}
翻译为
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public class LogExample {
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private static final java.util.logging.Logger log = java.util.logging.Logger.getLogger(LogExample.class.getName());
-
-
public static void main(String... args) {
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log.error("Something's wrong here");
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}
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}
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public class LogExampleOther {
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private static final org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(LogExampleOther.class);
-
-
public static void main(String... args) {
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log.error("Something else is wrong here");
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}
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}
-
-
public class LogExampleCategory {
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private static final org.apache.commons.logging.Log log = org.apache.commons.logging.LogFactory.getLog("CounterLog");
-
-
public static void main(String... args) {
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log.error("Calling the 'CounterLog' with a message");
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}
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}
所有支持的log类型:
@CommonsLog
Createsprivate static final org.apache.commons.logging.Log log = org.apache.commons.logging.LogFactory.getLog(LogExample.class);
@JBossLog
Createsprivate static final org.jboss.logging.Logger log = org.jboss.logging.Logger.getLogger(LogExample.class);
@Log
Createsprivate static final java.util.logging.Logger log = java.util.logging.Logger.getLogger(LogExample.class.getName());
@Log4j
Createsprivate static final org.apache.log4j.Logger log = org.apache.log4j.Logger.getLogger(LogExample.class);
@Log4j2
Createsprivate static final org.apache.logging.log4j.Logger log = org.apache.logging.log4j.LogManager.getLogger(LogExample.class);
@Slf4j
Creates private static final org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(LogExample.class);
@XSlf4j
Createsprivate static final org.slf4j.ext.XLogger log = org.slf4j.ext.XLoggerFactory.getXLogger(LogExample.class);
扩展配置:
lombok.log.fieldName
= an
identifier (default: log
).生成log字段的名称
默认为loglombok.log.fieldIsStatic
=
[true
| false
]
(default: true)生成log是否是static的 默认为static
官方文档说明:https://projectlombok.org/features/all
Lombok原理
lombok通过简单的注解标志就能够实现复杂的代码生成,他是怎么做到的?
lombok注解不是我们常见的runtime注解,而是source注解或者class注解,
在没有jsr之前我们可以通过反射在运行是获取注解值,但是这样效率很低,而且没办法做到编译检查,对开发人员一些不合的编码错误给出警告,
lombok本质上就是这样的一个实现了"JSR 269 API"的程序。在使用javac的过程中,它产生作用的具体流程如下:
1)javac对源代码进行分析,生成一棵抽象语法树(AST)
2)运行过程中调用实现了"JSR 269 API"的lombok程序
3)此时lombok就对第一步骤得到的AST进行处理,找到@Data注解所在类对应的语法树(AST),然后修改该语法树(AST),增加getter和setter方法定义的相应树节点
4)javac使用修改后的抽象语法树(AST)生成字节码文件,即给class增加新的节点(代码块)
ide中使用Lombok的注意事项
1.项目中要使用lombok 不仅ide要支持(否则一堆错误),项目中也要引入jar包
2.如果配置lombok.config文件,修改文件的属性值后,并不会自动重新编译class文件,ide编辑器也不会自动更新,所有每次修改配置文件后最后关闭java文件窗口重新打开,并且clean下项目