java追加CompiledScript或添加两个CompiledScript

Question

您好，我正在使用Groovy引擎来评估某个脚本。问题是执行时间有点大，所以我想把我的脚本分成两个脚本。第一个是静态的，可以在@PostConstruct方法中编译；第二个是变量，它取决于用户选择的一些参数。这就是我想做的：

Bindings bindings;
CompiledScript scriptC;
String script1="Static Script";
String script2="Variable Script";
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("groovy");
scriptC = ((Compilable) engine).compile(script1); 
//Execute some instruction to generate 'script2'
scriptC += ((Compilable) engine).compile(script2);//Please note the += operator

或

Bindings bindings;
CompiledScript scriptC;
String script1="Static Script";
String script2="Variable Script";
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("groovy");
scriptC = ((Compilable) engine).compile(script1); 
//Execute some instruction to generate 'script2'
scriptC.append(((Compilable) engine).compile(script2));//Please note the append function

这两个代码肯定不能工作，我使用它们只是为了说明我正在尝试做什么。是否可以将两个脚本合并为一个脚本

Answer 1

不能像那样组合两个CompiledScript对象。如果是Groovy，当Groovy脚本被编译时，它会创建一个扩展groovy.lang.Script的类，其中包含一些方法。在这种情况下，向彼此添加两个脚本意味着合并两个Java类

考虑在分离中评估两个脚本作为备选方案。请看以下示例：

import javax.script.Bindings;
import javax.script.Compilable;
import javax.script.CompiledScript;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
import javax.script.SimpleBindings;

public class ScriptTest {

    public static void main(String[] args) throws ScriptException {
        final ScriptEngineManager manager = new ScriptEngineManager();
        final ScriptEngine engine = manager.getEngineByName("Groovy");

        final Bindings bindings = new SimpleBindings();
        bindings.put("a", 3);

        final String script1 = "println 'Running first script...'; def c = 2; def d = c + a; return d";
        final CompiledScript compiledScript1 = ((Compilable) engine).compile(script1);

        //Execute some instruction to generate 'script2'
        final String script2 = "println 'Running second script...';";
        final CompiledScript compiledScript2 = ((Compilable) engine).compile(script2);

        Integer returnedValue = (Integer) compiledScript1.eval(bindings);
        System.out.println("Returned value from the first script: " + returnedValue);

        if (returnedValue > 1) {
            compiledScript2.eval(bindings);
        }
    }
}

创建CompiledScript对象是一回事。第二件事是评估这些脚本。如果您总是立即对script1和script2进行评估，那么您只需要：

compiledScript1.eval(bindings);
compiledScript2.eval(bindings);

但是script1可能会返回一些值，根据该值，您可以决定是否应该对script2进行评估。假设script1返回一个Integer，我将仅在返回值大于1时计算script2：

Integer returnedValue = (Integer) compiledScript1.eval(bindings);
if (returnedValue > 1) {
    compiledScript2.eval(bindings);
}

或者，您可以在运行script1之后基于绑定值。假设script1修改绑定a和b，并将两者设置为true（假设它们持有boolean类型）：

compiledScript1.eval(bindings);
if (bindings.get("a") && bindings.get("b")) {
    compiledScript2.eval(bindings);
}

从script2

调用script1中定义的函数

假设script1的定义如下：

import groovy.json.JsonOutput

def json(Map map) {
    return new JsonOutput().toJson(map)
}

println json([test: 1])

如果您必须在script2内调用json(map)函数，您可以这样做。看看这个例子：

import javax.script.Bindings;
import javax.script.Compilable;
import javax.script.CompiledScript;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
import javax.script.SimpleBindings;

public class ScriptTest {

    public static void main(String[] args) throws ScriptException {
        final ScriptEngineManager manager = new ScriptEngineManager();
        final ScriptEngine engine = manager.getEngineByName("Groovy");

        final Bindings bindings = new SimpleBindings();
        bindings.put("a", 3);

        final String script1 = "import groovy.json.JsonOutput\n" +
                "\n" +
                "def json(Map map) {\n" +
                "    return new JsonOutput().toJson(map)\n" +
                "}\n" +
                "\n" +
                "println json([test: 1])";

        final CompiledScript compiledScript1 = ((Compilable) engine).compile(script1);

        //Execute some instruction to generate 'script2'
        final String script2 = "println 'Running second script...'; println json([test: 2]);";
        final CompiledScript compiledScript2 = ((Compilable) engine).compile(script2);

        compiledScript1.eval(bindings);
        compiledScript2.eval(bindings);
    }
}

script2定义为：

println 'Running second script...';
println json([test: 2]);

运行时，您将在控制台中看到：

{"test":1}
Running second script...
{"test":2}

前两行来自script1，而最后一行由script2生成。请记住，这两个CompiledScript都包含对同一个引擎的引用，因此您可以引用在先前评估的脚本中定义的函数