Graalvm初步尝鲜

graalvm

官网：

https://www.graalvm.org/docs/getting-started/

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1、解压

tar -xvf graalvm-ee-darwin-amd64-19.2.0.1.tar.gz

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2、设置PATH

export PATH=/Users/lemonhall/development/graalvm-ee-19.2.0.1/Contents/Home/bin:$PATH

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3、设置JAVA_HOME

export JAVA_HOME=/Users/lemonhall/development/graalvm-ee-19.2.0.1/Contents/Home

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4、多语言

node中掺杂java

node --jvm --polyglot index.js

const express = require('express');

const app = express();

app.listen(3000);

app.get('/', function(req, res) {

var text = 'Hello World!';

const BigInteger = Java.type(

'java.math.BigInteger');

text += BigInteger.valueOf(2)

.pow(100).toString(16);

res.send(text);

})

然后就是http://192.168.50.138:3000/

看到：

Hello World!10000000000000000000000000

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5、java访问js

import org.graalvm.polyglot.*;

class Polyglot {

public static void main(String[] args) {

Context polyglot = Context.create();

Value array = polyglot.eval("js", "[1,2,42,4]");

int result = array.getArrayElement(2).asInt();

System.out.println(result);

}

}

javac Polyglot.java

java Polyglot

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6、互访

https://www.graalvm.org/docs/reference-manual/embed/

测试一下用js来当做规则引擎；

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7、spring boot

https://spring.io/projects/spring-boot/

7.1 安装maven

http://maven.apache.org/

7.1.1 下载

http://maven.apache.org/download.cgi

下载：

wget http://mirrors.tuna.tsinghua.edu.cn/apache/maven/maven-3/3

.6.2/binaries/apache-maven-3.6.2-bin.tar.gz

tar zxvf apache-maven-3.6.2-bin.tar.gz

7.1.2 安装

配置一下PATH

export PATH="$PATH:/Users/lemonhall/development/apache-maven-3.6.2/bin"

7.1.3 验证

mvn -v

7.2 安装spring boot

https://start.spring.io/

界面上一定要选上web，否则啥都干不了了

package com.example.demo;

import org.springframework.boot.*;

import org.springframework.boot.autoconfigure.*;

import org.springframework.web.bind.annotation.*;

@SpringBootApplication

@RestController

@EnableAutoConfiguration

public class DemoApplication {

@RequestMapping("/")

String home() {

return "Hello World!";

}

public static void main(String[] args) {

SpringApplication.run(DemoApplication.class, args);

}

}

运行起来：

mvn spring-boot:run

验证：

http://192.168.50.138:8080/

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8、整合spring-boot和graalvm

8.1 小改一下试试

加入

import org.graalvm.polyglot.*;

修改home函数为：

@RequestMapping("/")

String home() {

Context polyglot = Context.create();

Value array = polyglot.eval("js", "[1,2,42,4]");

int result = array.getArrayElement(2).asInt();

return "Hello World! "+result;

}

然后最后文件长这样：

package com.example.demo;

import org.springframework.boot.*;

import org.springframework.boot.autoconfigure.*;

import org.springframework.web.bind.annotation.*;

import org.graalvm.polyglot.*;

@SpringBootApplication

@RestController

@EnableAutoConfiguration

public class DemoApplication {

@RequestMapping("/")

String home() {

Context polyglot = Context.create();

Value array = polyglot.eval("js", "[1,2,42,4]");

int result = array.getArrayElement(2).asInt();

return "Hello World! "+result;

}

public static void main(String[] args) {

SpringApplication.run(DemoApplication.class, args);

}

}

然后是编译：

mvn compile

运行起来：

mvn spring-boot:run

验证：

http://192.168.50.138:8080/

结果是：Hello World! 42

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8.2 深入一点点

package com.example.demo;

import org.springframework.boot.*;

import org.springframework.boot.autoconfigure.*;

import org.springframework.web.bind.annotation.*;

import org.graalvm.polyglot.*;

@SpringBootApplication

@RestController

@EnableAutoConfiguration

public class DemoApplication {

Context context = Context.newBuilder()

.allowAllAccess(true)

.build();

@RequestMapping("/")

String home() {

String route01 = "var a='Hello From route01';";

String route02 = "function test(){"+

"var a='Hello From route02';"+

"return a;"+

"}"+

" test();";

context.getBindings("js").putMember("javaNumber", 42);

String result = context.eval("js",route02).asString();

return result;

}

public static void main(String[] args) {

SpringApplication.run(DemoApplication.class, args);

}

}

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8.3 结合真实例子来搞

https://www.xttblog.com/?p=2601

JAVA规则引擎 Drools 教程

其实本质上来说，JAVA的规则引擎就是个if else then 执行器

入参都是从外部给过来的，执行的动作也是；

给js的上下文（规则引擎当中注入java的操作）；

package com.example.demo;

import org.springframework.boot.*;

import org.springframework.boot.autoconfigure.*;

import org.springframework.web.bind.annotation.*;

import org.graalvm.polyglot.*;

@SpringBootApplication

@RestController

@EnableAutoConfiguration

public class DemoApplication {

public class Services {

@HostAccess.Export

public void createEmployee(String name) {

System.out.println(name);

}

public void exitVM() {

System.exit(1);

}

}

Context context = Context.newBuilder()

.allowAllAccess(true)

.build();

Services services = new Services();

@RequestMapping("/")

String home() {

String route01 = "var a='Hello From route01';";

String route02 = "function test(){"+

"var a='Hello From route02';"+

"let emp = services.createEmployee('John Doe');"+

"console.log('console from guest language');"+

"return a;"+

"}"+

" test();";

context.getBindings("js").putMember("javaNumber", 42);

context.getBindings("js").putMember("services", services);

String result = context.eval("js",route02).asString();

return result;

}

public static void main(String[] args) {

SpringApplication.run(DemoApplication.class, args);

}

}

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每次执行都能正确返回：

2019-10-22 13:42:46.680 INFO 8279 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : Completed initialization in 3 ms

John Doe

console from guest language

John Doe

console from guest language

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8.4 写一个接近于话费充值的例子

TODO

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8.5 写一个从配置文件读取规则js并动态执行的例子