Struts——OGNL表达式与Struts2结合

Posted 2020-10-25 想54256

一、OGNL表达式

OGNL:对象视图导航语言. ${user.addr.name} 这种写法就叫对象视图导航.

OGNL不仅仅可以视图导航而且还支持比EL表达式更加丰富的功能.

 

语法：

public void func() throws OgnlException {
    // 1.准备Root
    User rootUser = new User("jiaxin",23);
    // 2.准备Context
    Map<String,User> context = new HashMap<String,User>();

    context.put("user1",new User("计震宇",22));
    context.put("user2",new User("baoyan",25));
    // 3.实例化OnglContext
    OgnlContext oc = new OgnlContext();
    // 4.设置进OnglContext中
    oc.setRoot(rootUser);
    oc.setValues(context);

    // ***************从root中取值***************
    String name = (String) Ognl.getValue("name", oc, oc.getRoot());
    Integer age = (Integer) Ognl.getValue("age", oc, oc.getRoot());

    System.out.println("name:"+name+"\\tage:"+age);

    // ***************从context中取值***************
    String name1 = (String) Ognl.getValue("#user1.name", oc, oc.getRoot());
    Integer age1 = (Integer) Ognl.getValue("#user1.age", oc, oc.getRoot());

    System.out.println("name:"+name1+"\\tage:"+age1);

    // ***************赋值****************
    Ognl.getValue("name=\'计宝宝\'", oc, oc.getRoot());
    String name2 = (String) Ognl.getValue("name", oc, oc.getRoot());

    // 先改值再取值
    String name3 = (String) Ognl.getValue("#user1.name=\'计宝宝\',#user1.name", oc, oc.getRoot());

    System.out.println(name2+"\\t"+name3);

    // *****************调普通方法****************
    String name4 = (String) Ognl.getValue("setName(\'计震宇\'),getName()", oc, oc.getRoot());

    String name5 = (String) Ognl.getValue("#user2.setName=\'张军\',#user2.getName()", oc, oc.getRoot());

    System.out.println(name4+"\\t"+name5);

    // *****************调用静态方法*****************
    Double PI = (Double) Ognl.getValue("@java.lang.Math@PI",oc,oc.getRoot());
    Double PI2 = (Double) Ognl.getValue("@@PI",oc,oc.getRoot());

    System.out.println(PI);

    // ******************创建List，Map对象****************
    Integer len = (Integer) Ognl.getValue("{\'ji\',\'zhen\',\'yu\',\'bao\'}.size()", oc, oc.getRoot());
    String value = (String) Ognl.getValue("{\'ji\',\'zhen\',\'yu\',\'bao\'}.get(0)", oc, oc.getRoot());
    String value2 = (String) Ognl.getValue("{\'ji\',\'zhen\',\'yu\',\'bao\'}[2]", oc, oc.getRoot());

    System.out.println(len+"\\t"+value+"\\t"+value2);

    // 字典前面要加“#”，注意和取context中的内个“#”没有任何关系
    Integer len2 = (Integer) Ognl.getValue("#{\'k1\':\'v1\',\'k2\':\'v2\'}.size()",oc,oc.getRoot());
    String value3 = (String) Ognl.getValue("#{\'k1\':\'v1\',\'k2\':\'v2\'}[\'k1\']",oc,oc.getRoot());
    String value4 = (String) Ognl.getValue("#{\'k1\':\'v1\',\'k2\':\'v2\'}[\'k2\']",oc,oc.getRoot());

    System.out.println(len2+"\\t"+value3+"\\t"+value4);
}

二、OGNL表达式与Struts2结合

 

1、三种接收参数的原理

 

 

2、获取参数

3、查找顺序