GroovyEngine加载数据库脚本

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我是靠谱客的博主高大大炮，最近开发中收集的这篇文章主要介绍GroovyEngine加载数据库脚本，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

Groovy是动态热编译语言，和java结束在低代码产品里能发挥不错的作用，那如何读取存放在数据库里的脚本记录，并且随着脚本的更改和更新？下面就给大家介绍一下。

1.首先我们需要实现一个 URLStreamHandler

package com.breeze.bms.groovy;

import com.breeze.bms.mybatis.domain.GroovyScript;
import com.breeze.bms.service.GroovyScriptService;
import com.breeze.bms.util.SpringUtil;
import com.google.common.base.Splitter;
import org.springframework.util.ObjectUtils;

import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLStreamHandler;
import java.util.List;

/**
 * @author breeze
 * @since 2022/3/21 11:32
 */
public class GroovyResourceStreamHandler extends URLStreamHandler {

    @Override
    protected URLConnection openConnection(URL u) throws IOException {
        GroovyScript groovyScript = null;//咱们自己定义的groovyScript对象
        if (!ObjectUtils.isEmpty(u.getPath())) {
            List<String> paths = Splitter.on("/").omitEmptyStrings().splitToList(u.getPath());
            if (!ObjectUtils.isEmpty(paths) && paths.size() == 2) {
//从数据库里加载
                groovyScript = SpringUtil.getBean(GroovyScriptService.class).loadGroovyScript(paths.get(0), paths.get(1).replaceAll(".groovy",""));
            }
        }

        if (ObjectUtils.isEmpty(groovyScript))
            throw new IOException("没有可执行groovy脚本！");

        GroovyResourceConnection connection = new GroovyResourceConnection(u, groovyScript);
        return connection;

    }
}

定义resourceConnection

package com.breeze.bms.groovy;

import com.breeze.bms.mybatis.domain.GroovyScript;
import com.breeze.bms.service.GroovyScriptService;
import com.breeze.bms.util.G;
import com.breeze.bms.util.SpringUtil;
import org.codehaus.groovy.ant.Groovy;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;

/**
 * @author breeze
 * @since 2022/3/21 11:29
 */
public class GroovyResourceConnection extends URLConnection {

    private final GroovyScript groovyScript;

    protected GroovyResourceConnection(URL url, GroovyScript groovyScript) {
        super(url);
        this.groovyScript = groovyScript;
    }

    @Override
    public void connect() throws IOException {
        this.connected = true;
    }

    @Override
    public InputStream getInputStream() throws IOException {
        this.connect();
        return new ByteArrayInputStream(groovyScript.getScriptText().getBytes());
    }
    //这个方法是核心，groovy引擎判断是否需要重新加载
    public long getLastModified() {
        GroovyScript temp = SpringUtil.getBean(GroovyScriptService.class).infoWithoutScriptText(groovyScript.getId());
        return G.l(temp.getUpdateTime(),0);
    }
}

2.指定groovy协议解析类

/**
 * @author breeze
 * @since 2022/6/9 14:59
 */
public class GroovyURLStreamHandlerFactory implements URLStreamHandlerFactory {
    @Override
    public URLStreamHandler createURLStreamHandler(String protocol) {
        return "groovy".equals(protocol) ? new GroovyResourceStreamHandler() : null;
    }
}

3.具体使用就可以使用groovy协议

GroovyScriptEngine groovyScriptEngine; = new GroovyScriptEngine(new URL[]{new URL(null, "groovy://db/system/", new GroovyResourceStreamHandler())});

Binding binding = new Binding();
Script script = groovyScriptEngine.createScript(groovyScript.getScriptName() + ".groovy", binding);
if (script != null) {
    return script.invokeMethod(methodName, params);
}

更多详细源码请关注 https://gitee.com/wtr/BMS-VUE