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java 对字符串转为可执行代码

admin 11月 12, 2020 0

方法一

参考: java实现字符串转换成可执行代码

使用commons的jexl包

  <dependency>
          <groupId>org.apache.commons</groupId>
          <artifactId>commons-jexl</artifactId>
          <version>2.0</version>
  </dependency>

代码示例

Map<String,Object> map = new HashMap<String,Object>();
map.put("testService",testService);
map.put("person", person);
String expression="testService.save(person)";

JexlEngine jexl=new JexlEngine();
Expression e = jexl.createExpression(expression);
JexlContext jc = new MapContext();
for(String key:map.keySet()){
      jc.set(key, map.get(key));
}
Object o = e.evaluate(jc);

方式二

参考:java执行字符串数学表达式 ScriptEngine

使用Java自带的jdk, javax.script.ScriptEngine

  String str = "a&&b&&c";
  ScriptEngineManager factory = new ScriptEngineManager();
  ScriptEngine engine = factory.getEngineByName("JavaScript");
  str = str.replace("a", "true");
  str = str.replace("b", "true");
  str = str.replace("c", "false");
  Object o = null;
  try {
      o = engine.eval(str);
  } catch (ScriptException e) {
      e.printStackTrace();
  }finally {
      System.out.println("o = " + o);
  }