java 几个不错的编译器

janino以及javacc是不错的选择，都是好多框架的选择

janino 参考使用

• pom.xml

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0"

         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>

 

    <groupId>com.dalong</groupId>

    <artifactId>javacapp</artifactId>

    <version>1.0-SNAPSHOT</version>

 

    <properties>

        <maven.compiler.source>8</maven.compiler.source>

        <maven.compiler.target>8</maven.compiler.target>

    </properties>

    <dependencies>

        <dependency>

            <groupId>org.codehaus.janino</groupId>

            <artifactId>janino</artifactId>

            <version>3.1.3</version>

        </dependency>

        <dependency>

            <groupId>me.nimavat</groupId>

            <artifactId>shortid</artifactId>

            <version>1.0.1.RC1</version>

        </dependency>

    </dependencies>

 

    <repositories>

        <repository>

            <id>demo</id>

            <url>http://dl.bintray.com/snimavat/maven</url>

        </repository>

    </repositories>

</project>

• main

package com.dalong;

 

import org.codehaus.commons.compiler.CompileException;

import org.codehaus.janino.ScriptEvaluator;

import java.lang.reflect.InvocationTargetException;

import java.util.Arrays;

 

public class App {

    static void method1(String item) {

        System.out.printf(item);

    }

    public static void main(String[] args) throws CompileException, InvocationTargetException {

        ScriptEvaluator se = new ScriptEvaluator();

        se.cook(

                ""

                        + "static void method1() {\n"

                        + "    System.out.println(1);\n"

                        + "}\n"

                        + "\n"

                        + "method1();\n"

                        + "method2();\n"

                        + "\n"

                        + "static void method2() {\n"

                        + " System.out.println(me.nimavat.shortid.ShortId.generate().toString());\n"

                        + "}\n"

        );

        Arrays.stream(se.getDefaultImports()).iterator().forEachRemaining(App::method1);

        se.evaluate(new Object[0]);

    }

}

javacc

javacc 的使用就有点复杂了，需要定义自己的schema 然后进行代码生成

• 下载jar
  参考地址:https://javacc.github.io/javacc/ 注意下载jar 包，同时重命名为javacc.jar
• 配置命令
  javacc shell 同时添加执行权限

 

#!/bin/sh

java -classpath javacc.jar javacc "$@"

• 创建一个简单的schema

options {

    STATIC = false;

}

 

PARSER_BEGIN(Adder)

import java.io.*;

 

class Adder {

    public static void main(String[] args) {

        for (String arg : args) {

            try {

                System.out.println(evaluate(arg));

            } catch (ParseException ex) {

                System.err.println(ex.getMessage());

            }

        }

    }

 

    public static long evaluate(String src) throws ParseException {

        Reader reader = new StringReader(src);

        return new Adder(reader).expr();

    }

}

PARSER_END(Adder)

 

SKIP: { <[" ", "\t", "\r", "\n"]> }

 

TOKEN: {

    <INTEGER: (["0"-"9"])+>

}

 

long expr():

{

    Token x, y;

}

{

    x=<INTEGER> "+" y=<INTEGER> <EOF>

    {

        return Long.parseLong(x.image) + Long.parseLong(y.image);

    }

}

• 生成代码

./javacc app.jj

• 效果

 

 

• 编译执行

javac Adder.java
java Adder 1+2

 

 

参考资料

https://github.com/javacc/javacc
https://github.com/janino-compiler/janino
https://github.com/apache/calcite/blob/master/core/src/main/codegen/templates/Parser.jj