在開發(fā)過程中我們可能需要通過Java來調(diào)用執(zhí)行JavaScript腳本，比如我們在用Java做網(wǎng)絡(luò)爬蟲時，有時需要執(zhí)行JS代碼來對一些請求的參數(shù)進行加密。下面簡單介紹一下如何用Java執(zhí)行JS腳本代碼。

簡單的使用:

package com.my.js;

import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;

public class First {
    /**
     * 
     * @param jsStr js腳本內(nèi)容
     * @param function  要調(diào)用的js方法名
     * @param args  調(diào)用js方法時傳入的參數(shù)
     * @return
     */
    public static Object jsObjFunc(String jsStr,String function,Object... args) {
        ScriptEngineManager sem = new ScriptEngineManager();
        ScriptEngine scriptEngine = sem.getEngineByName("js");
        try {
            scriptEngine.eval(jsStr);
            Invocable inv2 = (Invocable) scriptEngine;
            return  inv2.invokeFunction(function,args);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
    public static void main(String[] args)throws Exception {
        String jsStr ="function myFuc(param){return \"the param is:\"+param;}";//js腳本內(nèi)容
        System.out.println(jsObjFunc(jsStr,"myFuc","test"));
    }
}

針對多次調(diào)用的優(yōu)化，并進行簡單的封裝后：

package com.my.js;

import javax.script.*;
import java.util.Map;

public class ScriptCompile {
    CompiledScript script;
    ScriptEngine engine ;
    ScriptCompile(String scriptText){
        this.script =initScript(scriptText,null);
    }
    /**
     *
     * @param scriptText    js腳本內(nèi)容
     * @param initParams    在編譯時, 初始化時傳入腳本的參數(shù)
     */
    ScriptCompile(String scriptText,Map<String,Object> initParams){   //構(gòu)造函數(shù), 先編譯
        this.script =initScript(scriptText,initParams);
    }
    public CompiledScript initScript(String scriptText,Map<String,Object> initParams){
        CompiledScript script =null;
        ScriptEngine engine = new ScriptEngineManager().getEngineByExtension("js");
        if(initParams!=null&&!initParams.isEmpty()) {
            for (Map.Entry<String, Object> entry : initParams.entrySet()) {
                engine.put(entry.getKey(), entry.getValue());
            }
        }
        this.engine= engine;
        if (engine instanceof Compilable) {
            try {
                script = ((Compilable) engine).compile(scriptText);
            } catch (ScriptException e) {
                e.printStackTrace();
            }
        }
        return script;
    }

    /**
     * 執(zhí)行腳本
     * @param bindingsMap   本次執(zhí)行時傳入的參數(shù)
     * @return
     * @throws ScriptException
     */
    public Object execute(Map<String,Object> bindingsMap) throws ScriptException {
        if(bindingsMap!=null&&!bindingsMap.isEmpty()){
            Bindings bindings = new SimpleBindings();
            for(Map.Entry<String,Object> entry: bindingsMap.entrySet()){
                bindings.put(entry.getKey(),entry.getValue());
            }
            return script.eval(bindings);
        }else{
            return script.eval();
        }
    }
    public Object execute() throws ScriptException {
        return execute(null);
    }

    /**
     * 調(diào)用腳本中的某個函數(shù)
     * @param bindingsMap   本次執(zhí)行傳入的參數(shù)
     * @param fucName  函數(shù)名
     * @param args  函數(shù)參數(shù),可以有多個參數(shù)
     * @return
     * @throws Exception
     */
    public Object executeFuc(Map<String,Object> bindingsMap,String fucName,Object...args) throws Exception {
        execute(bindingsMap);
        Invocable inv2 = (Invocable) engine;
        return  inv2.invokeFunction(fucName,args);
    }
    public Object executeFuc(String fucName,Object...args) throws Exception {
        return executeFuc(null,fucName,args);
    }
}

調(diào)用:

    public static void main(String[] args) {
        Map<String,Object> map=new HashMap<>();
        map.put("counter",9);
        ScriptCompile sc = new ScriptCompile(
                "function count(num) {counter = counter +num; " +
                " return counter; }; " +
//                "count();" +
                "",map);

        for(int i=0;i<5;i++) {
            try {
//                map.put("counter",9);   //本次執(zhí)行 要傳遞的參數(shù)
//                System.out.println(sc.run());
                System.out.println(sc.executeFuc("count",2));
            } catch (Exception ex) {
                ex.printStackTrace();
            }
        }
    }

執(zhí)行結(jié)果:
11.0
13.0
15.0
17.0
19.0