Struts2--OGNL语法详解（取值、赋值、调用普通方法、调用静态方法、创建List和Map）

男娘i 2021-08-13 17:43 472阅读 0赞

#### 创建项目并导包 ####

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70]

#### 创建一个User类 ####

package cn.itheima.bean;
    
    public class User { 
    	private String name;
    	private Integer age;
    	
    	public User() { 
    		super();
    	}
    	public User(String name, Integer age) { 
    		super();
    		this.name = name;
    		this.age = age;
    	}
    	public String getName() { 
    		return name;
    	}
    	public void setName(String name) { 
    		this.name = name;
    	}
    	public Integer getAge() { 
    		return age;
    	}
    	public void setAge(Integer age) { 
    		this.age = age;
    	}
    	@Override
    	public String toString() { 
    		return "User [name=" + name + ", age=" + age + "]";
    	}
    }

#### 准备工作 ####

@Test
    //准备工作
    public void fun1() throws Exception{ 
    	//准备ONGLContext
    		//准备Root
    		User rootUser = new User("tom",18);
    		//准备Context
    		Map<String,User> context = new HashMap<String,User>();
    		context.put("user1", new User("jack",18));
    		context.put("user2", new User("rose",22));
    	OgnlContext oc = new OgnlContext();
    	//将rootUser作为root部分
    	oc.setRoot(rootUser);
    	//将context这个Map作为Context部分
    	oc.setValues(context);
    	//书写OGNL
    	Ognl.getValue("", oc, oc.getRoot());
    }

#### 取root中的属性值 ####

@Test
    //取出root中的属性值
    public void fun2() throws Exception{ 
    	//准备ONGLContext
    		//准备Root
    		User rootUser = new User("tom",18);
    		//准备Context
    		Map<String,User> context = new HashMap<String,User>();
    		context.put("user1", new User("jack",18));
    		context.put("user2", new User("rose",22));
    	OgnlContext oc = new OgnlContext();
    	oc.setRoot(rootUser);
    	oc.setValues(context);
    	//书写OGNL
    	
    	//取出root中user对象的name属性
    	String name = (String) Ognl.getValue("name", oc, oc.getRoot());
    	Integer age = (Integer) Ognl.getValue("age", oc, oc.getRoot());
    	System.out.println(name);
    	System.out.println(age);
    }

运行Junit测试，控制台打印：

tom
    18

#### 取出context中的属性值 ####

public void fun3() throws Exception{ 
    	//准备ONGLContext
    		//准备Root
    		User rootUser = new User("tom",18);
    		//准备Context
    		Map<String,User> context = new HashMap<String,User>();
    		context.put("user1", new User("jack",18));
    		context.put("user2", new User("rose",22));
    	OgnlContext oc = new OgnlContext();
    	oc.setRoot(rootUser);
    	oc.setValues(context);
    	//书写OGNL
    	
    	//取出context中键为user1对象的name属性
    	String name = (String) Ognl.getValue("#user1.name", oc, oc.getRoot());
    	String name2 = (String) Ognl.getValue("#user2.name", oc, oc.getRoot());
    	Integer age = (Integer) Ognl.getValue("#user2.age", oc, oc.getRoot());
    	System.out.println(name);
    	System.out.println(name2);
    	System.out.println(age);
    }

运行Junit测试，控制台打印：

jack
    rose
    22

#### 为属性赋值 ####

@Test
    //基本语法演示
    //为属性赋值
    public void fun4() throws Exception{ 
    	//准备ONGLContext
    		//准备Root
    		User rootUser = new User("tom",18);
    		//准备Context
    		Map<String,User> context = new HashMap<String,User>();
    		context.put("user1", new User("jack",18));
    		context.put("user2", new User("rose",22));
    	OgnlContext oc = new OgnlContext();
    	oc.setRoot(rootUser);
    	oc.setValues(context);
    	//书写OGNL
    	
    	//将root中的user对象的name属性赋值
    	Ognl.getValue("name='jerry'", oc, oc.getRoot());
    	String name = (String) Ognl.getValue("name", oc, oc.getRoot());
    	//将Context中的user对象的name属性赋值 
    	//可以使用（,）将表达式进行串联执行，但是多个表达式串联，如果有多个返回值，只返回最后一个表达式的
    	String name2 = (String) Ognl.getValue("#user1.name='二狗', #user1.name", oc, oc.getRoot());
    	System.out.println(name);
    	System.out.println(name2);
    }

运行Junit测试，控制台打印：

jerry
    二狗

#### 调用方法 ####

@Test
    //调用方法
    public void fun5() throws Exception{ 
    	//准备ONGLContext
    		//准备Root
    		User rootUser = new User("tom",18);
    		//准备Context
    		Map<String,User> context = new HashMap<String,User>();
    		context.put("user1", new User("jack",18));
    		context.put("user2", new User("rose",22));
    	OgnlContext oc = new OgnlContext();
    	oc.setRoot(rootUser);
    	oc.setValues(context);
    	//书写OGNL
    	
    	//调用root中user对象的setName方法
    	Ognl.getValue("setName('lilei')", oc, oc.getRoot());
    	String name = (String) Ognl.getValue("getName()", oc, oc.getRoot());
    	//调用context中user对象的setName方法
    	String name2 = (String) Ognl.getValue("#user1.setName('lucy'),#user1.getName()", oc, oc.getRoot());
    	
    	
    	System.out.println(name);
    	System.out.println(name2);
    }

运行Junit测试，控制台打印：

lilei
    lucy

#### 调用静态方法 ####

创建一个工具类，定义一个静态方法：

package pers.zhang.Utils;
    
    public class HahaUtils { 
    	
    	//回音方法
    	public static Object echo(Object o){ 
    		return o;
    	}
    }

@Test
    //基本语法演示
    //调用静态方法
    public void fun6() throws Exception{ 
    	//准备ONGLContext
    		//准备Root
    		User rootUser = new User("tom",18);
    		//准备Context
    		Map<String,User> context = new HashMap<String,User>();
    		context.put("user1", new User("jack",18));
    		context.put("user2", new User("rose",22));
    	OgnlContext oc = new OgnlContext();
    	oc.setRoot(rootUser);
    	oc.setValues(context);
    	//书写OGNL
    	//@+完整类名+@+方法
    	String name = (String) Ognl.getValue("@pers.zhang.Utils@echo('hello 强勇!')", oc, oc.getRoot());
    	//Double pi = (Double) Ognl.getValue("@java.lang.Math@PI", oc, oc.getRoot());
    	//访问Math的简写
    	Double pi = (Double) Ognl.getValue("@@PI", oc, oc.getRoot());
    	System.out.println(name);
    	System.out.println(pi);
    }

运行Junit测试，控制台打印：

hello 二狗
    3.141592653589793

#### ognl创建对象（List，Map） ####

@Test
    //基本语法演示
    //ognl创建对象-list|map
    public void fun7() throws Exception{ 
    	//准备ONGLContext
    		//准备Root
    		User rootUser = new User("tom",18);
    		//准备Context
    		Map<String,User> context = new HashMap<String,User>();
    		context.put("user1", new User("jack",18));
    		context.put("user2", new User("rose",22));
    	OgnlContext oc = new OgnlContext();
    	oc.setRoot(rootUser);
    	oc.setValues(context);
    	//书写OGNL
    	
    	//创建list对象
    	Integer size = (Integer) Ognl.getValue("{'tom','jerry','jack','rose'}.size()", oc, oc.getRoot());
    	String name = (String) Ognl.getValue("{'tom','jerry','jack','rose'}[0]", oc, oc.getRoot());
    	String name2 = (String) Ognl.getValue("{'tom','jerry','jack','rose'}.get(1)", oc, oc.getRoot());
    
    	/*System.out.println(size); System.out.println(name); System.out.println(name2);*/
    	//创建Map对象
    	Integer size2 = (Integer) Ognl.getValue("#{'name':'tom','age':18}.size()", oc, oc.getRoot());
    	String name3  = (String) Ognl.getValue("#{'name':'tom','age':18}['name']", oc, oc.getRoot());
    	Integer age  = (Integer) Ognl.getValue("#{'name':'tom','age':18}.get('age')", oc, oc.getRoot());
    	System.out.println(size2);
    	System.out.println(name3);
    	System.out.println(age);
    }

运行Junit测试，控制台输出：

2
    tom
    18

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