Ognl基本使用

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Ognl默认是从“根”中取数据的

下面Demo中用的是

Ognl.getValue(String expression, Map context, Object root)

这个方法。

// 参数1，填写Ognl表达式
// 参数2，Map类=》context上下文
// 参数3，JavaBean,Map,List````等类型，Root 根

Ognl需要的jar包：

先准备两个JavaBean

public class User {
    private String name;
    private int age;
    private Address address; 

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}

public class Address {
    private String city;

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }
}

下面列举Demo，方法中使用Ognl

public void func1() throws OgnlException {
        User user = new User();
        user.setName("Tom");
        String name = (String) Ognl.getValue("name", new HashMap(), user);
        System.out.println(name);
    }

//从List根中取数据
public void func2() throws OgnlException {
        List<User> list=new ArrayList<User>();
        User user = new User();
        user.setName("Tom");
        list.add(user);
        User user2=new User();
        user2.setName("Jerry");
        list.add(user2);
        //[1]代表list中第二个数据
        String name = (String) Ognl.getValue("[1].name", new HashMap(), list);
        System.out.println(name);
    }

//稍复杂的从JavaBean中取数据
    public void func4() throws OgnlException{
        User user=new User();
        Address address=new Address();
        address.setCity("北京");
        user.setAddress(address);
        String city=(String) Ognl.getValue("address.city", new HashMap(),user);
        System.out.println(city);
    }

//从第二个参数Map中取数据
    public void func3() throws OgnlException{
        Map<String, Object> context=new HashMap<String,Object>();
        context.put("name", "Tom");
        //为了验证确实是取自Map中，添加一个JavaBean
        User user=new User();
        user.setName("Jerry");
        //如果取自Map，则需要在name前加#，否则默认取自第三个JavaBean中
        String name = (String) Ognl.getValue("#name",context, user);
        System.out.println(name);
    }

// 用Ognl表达式用getValue方法给对象赋值
    public void func5() throws OgnlException {
        User user = new User();
        Integer age = (Integer) Ognl.getValue("age=23", new HashMap(), user);
        System.out.println(user.getAge());
        System.out.println(age);
    }

// 用Ognl表达式用setValue方法给对象赋值
    public void func6() throws OgnlException {
        User user = new User();
        Ognl.setValue("age", new HashMap(), user,23);
        System.out.println(user.getAge());
    }

 在User类中新增一个非静态方法和一个静态方法

public static String getNowTime1(){
        return new SimpleDateFormat("yyyy/MM/dd").format(new Date());
    }
    public String getNowTime2(){
        return new SimpleDateFormat("yyyy-MM-dd").format(new Date());
    }

// 调用根中方法
    public void func7() throws OgnlException {
        // 静态方法和普通方法调用方式一样
        User user = new User();
        String nowTime1 = (String) Ognl.getValue("getNowTime1()", new HashMap<>(), user);
        String nowTime2 = (String) Ognl.getValue("getNowTime2()", new HashMap<>(), user);
        System.out.println(nowTime1);
        System.out.println(nowTime2);
    }

为了测试调用其他类中方法，新增一个类

import java.text.SimpleDateFormat;
import java.util.Date;

public class DateUtils {
    public static String getNowTime1(String format) {
        return new SimpleDateFormat(format).format(new Date());
    }

    public String getNowTime2(String format) {
        return new SimpleDateFormat(format).format(new Date());
    }
}

// 调用其他类静态方法并传参数
    public void func8() throws OgnlException {
        // 使用@符号调用其他类中静态方法，不再受必须在根中的限制
        User user = new User();
        String nowTime = (String) Ognl.getValue("@cn.hjp.utils.DateUtils@getNowTime1('yyyy-MM/dd')", new HashMap<>(),
                user);
        System.out.println(nowTime);
    }

 在DateUtils类中新增一公共变量 public static Double d=12.34;进行下面测试

//调用其他类中静态变量
    public void func9() throws OgnlException{
        User user=new User();
        Double d=(Double) Ognl.getValue("@cn.hjp.utils.DateUtils@d", new HashMap<>(),
                user);
        System.out.println(d);
    }

//进行运算
    public void func10() throws OgnlException{
        User user=new User();
        Integer d=(Integer) Ognl.getValue("1+1", new HashMap<>(),
                user);
        System.out.println(d);
    }

// 逗号“,”连接符的使用
    public void func11() throws OgnlException {
        User user = new User();
        // 多表达式，逗号分隔，都参与运算，只是最后一个才会返回结果
        String name = (String) Ognl.getValue("name='Tom',name", new HashMap<>(), user);
        Integer age = (Integer) Ognl.getValue("name='Tom',age=23", new HashMap<>(), user);
        System.out.println(name);
        System.out.println(age);
    }

// 创建List集合
    public void func12() throws OgnlException {
        User user = new User();
        List list = (List) Ognl.getValue("{'Tom','Lily','Jerry','Jack'}", new HashMap<>(), user);
        System.out.println(list);
    }

// 创建Map,要使用#符号，指定为Map类型
    public void func13() throws OgnlException {
        User user = new User();
        Map map = (Map) Ognl.getValue("#{'name':'Tom','age':23}", new HashMap<>(), user);
        System.out.println(map);
    }

 方便演示创建对象，重写User类的ToString方法：

public String toString() {
return "User [name=" + name + ", age=" + age + ", address=" + address + "]";
}

// 使用Ognl创建对象
    public void func14() throws OgnlException {
        User user1=new User();
        User user2 = (User) Ognl.getValue("new cn.hjp.bean.User()",new HashMap<>(), user1);
        System.out.println(user2);
    }

//Ognl中的in和 not in 运算符
    public void func15() throws OgnlException{
        User user=new User();
        Boolean exists=(Boolean) Ognl.getValue("'Tom' in {'Tom','Lily','Jerry','Jack'}", new HashMap<>(), 
                user);
        Boolean notexists=(Boolean) Ognl.getValue("'Tom' not in {'Tom','Lily','Jerry','Jack'}", new HashMap<>(), 
                user);
        System.out.println(exists);
        System.out.println(notexists);
    }

// 集合投影
    public void func16() throws OgnlException {
        List<User> list = new ArrayList<User>();
        User user1 = new User();
        user1.setName("Tom");
        user1.setAge(23);
        list.add(user1);
        User user2 = new User();
        user2.setName("Jerry");
        user2.setAge(24);
        list.add(user2);
        //只获取name属性
        List l = (List) Ognl.getValue("#this.{name}", new HashMap<>(), list);
        System.out.println(l);
    }

// 集合选择
    public void func17() throws OgnlException {
        List<User> list = new ArrayList<User>();
        User user1 = new User();
        user1.setName("Tom");
        user1.setAge(17);
        list.add(user1);
        User user2 = new User();
        user2.setName("Jerry");
        user2.setAge(24);
        list.add(user2);
        //只获取name属性
        List l = (List) Ognl.getValue("#this.{?age>18}", new HashMap<>(), list);
        System.out.println(l);
    }