JDK1.6版添加了新的ScriptEngine類，允許用戶直接執行js代碼。

在Java中直接調用js代碼

不能調用瀏覽器中定義的js函數，會拋出異常提示ReferenceError:?“alert”?is?not?defined。

[java]?view plain?copy

package?com.sinaapp.manjushri;???

import?javax.script.ScriptEngine;???

import?javax.script.ScriptEngineManager;??

import?javax.script.ScriptException;???/**??*?直接調用js代碼??*/??

??????????

??public?class?ScriptEngineTest?{??????

????public?static?void?main(String[]?args)?{???

????????ScriptEngineManager?manager?=?new?ScriptEngineManager();??

????????ScriptEngine?engine?=?manager.getEngineByName("javascript");??

??????????try?{??????

????????????engine.eval("var?a=3;?var?b=4;print?(a+b);");??????

????????????//?不能調用瀏覽器中定義的js函數??????

????????????//?engine.eval("alert(\"js?alert\");");?????

????????????//?錯誤，會拋出alert引用不存在的異常?????

??????????}?catch?(ScriptException?e)?{??

??????????????e.printStackTrace();?????

??????????}????

??????}?????

}??

輸出結果：7

在Java中綁定js變量

在調用engine.get(key);時，如果key沒有定義，則返回null

[java]?view plain?copy

package?com.sinaapp.manjushri;?????

import?javax.script.Bindings;???

import?javax.script.ScriptContext;???

import?javax.script.ScriptEngine;???

import?javax.script.ScriptEngineManager;???

import?javax.script.ScriptException;?????

????????????

public?class?ScriptEngineTest2?{???

????public?static?void?main(String[]?args)?{?????

????????ScriptEngineManager?manager?=?new?ScriptEngineManager();?????

??????????ScriptEngine?engine?=?manager.getEngineByName("javascript");?????

??????????engine.put("a",?4);???engine.put("b",?3);?????

??????????Bindings?bindings?=?engine.getBindings(ScriptContext.ENGINE_SCOPE);??

??????????try?{??

??????????????//?只能為Double，使用Float和Integer會拋出異常??

??????????????Double?result?=?(Double)?engine.eval("a+b");??

??????????????System.out.println("result?=?"?+?result);??

??????????????engine.eval("c=a+b");??

??????????????Double?c?=?(Double)engine.get("c");??

??????????????System.out.println("c?=?"?+?c);??

??????????}?catch?(ScriptException?e)?{??

??????????????e.printStackTrace();?????

??????????}????

??????}???

??}??

輸出：
result?=?7.0
c?=?7.0

在Java中調用js文件中的function，傳入調用參數，并獲取返回值

js文件中的merge函數將兩個參數a，b相加，并返回c。
[javascript]?view plain?copy

//?expression.js???

function?merge(a,?b)?{???

?????c?=?a?*?b;???

?????return?c;???

}??

在Java代碼中讀取js文件，并參數兩個參數，然后回去返回值 [java]?view plain?copy

package?com.sinaapp.manjushri;????

?import?java.io.FileReader;????

?import?javax.script.Invocable;??

?import?javax.script.ScriptEngine;??

?import?javax.script.ScriptEngineManager;????

?/**??*?Java調用并執行js文件，傳遞參數，并活動返回值??*???*?@author?manjushri??*/??

?public?class?ScriptEngineTest?{?????

?????public?static?void?main(String[]?args)?throws?Exception?{?????

????????ScriptEngineManager?manager?=?new?ScriptEngineManager();?????

????????ScriptEngine?engine?=?manager.getEngineByName("javascript");??????

?????????String?jsFileName?=?"expression.js";????

?????????//?讀取js文件?????

????????FileReader?reader?=?new?FileReader(jsFileName);?????

????????//?執行指定腳本????

?????????engine.eval(reader);?????

????????if(engine?instanceof?Invocable)?{?????

?????????????Invocable?invoke?=?(Invocable)engine;??????

????????????//?調用merge方法，并傳入兩個參數?????

?????????????//?c?=?merge(2,?3);?????

?????????????Double?c?=?(Double)invoke.invokeFunction("merge",?2,?3);?????

?????????????System.out.println("c?=?"?+?c);?????

????????}?????

????reader.close();???

?}???

}??

輸出結果：
c?=?5.0

總結

以上是生活随笔為你收集整理的JDK1.6版添加了新的ScriptEngine类，允许用户直接执行js代码。的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。