继“Java 如何方便地访问深层的 map 的值？”

昨晚问了个问题：https://hacpai.com/article/1526989190264?p=1&m=1#1527061155002，今天写了个工具解决，暂时能用，边用边完善。
感谢
@88250 @Vanessa 的回复；

先看使用方法：

package utils;


import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.junit.Test;

import com.alibaba.fastjson.JSON;

public class T {

	@Test
	public void jsonMap() {
		SuperMap json = SuperMap.createInstence("{\"test\":{\"pp\":\"8983431w\"}, \"user\":{\"id\":123, \"username\":\"linus\", \"emails\":[\"email1\", \"email2\"]}}");

		System.out.println(json.get("test.pp", int.class));
		System.out.println(json.get("user", User.class));
		System.out.println(json.get("user.emalis[0]", String.class));
	}

	@Test
	public void testReg() {
		Pattern p = Pattern.compile("(\\w+)\\[(\\d+)\\]$");

		Matcher a = p.matcher("nihao[4]");
		a.find();
		System.out.println(a.group(2));
	}
}

class User {
	private Long id;
	private String username;
	private String[] emails;
	
	public String toString() {
		return JSON.toJSONString(this);
	}
	
	public Long getId() {
		return id;
	}
	public void setId(Long id) {
		this.id = id;
	}
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public String[] getEmails() {
		return emails;
	}
	public void setEmails(String[] emails) {
		this.emails = emails;
	}
}```

# 再看实现
```java
package utils;

import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;

/**
 * 一个map的子类，使用key path 获取map的值，以来fastjson
 * 
 * @author 水牛叔叔(cnliangwei@foxmail.com)
 *
 */
public class SuperMap extends HashMap<String, T> {
	private static final long serialVersionUID = 1L;
	private static final Pattern listReg = Pattern.compile("(\\w+)\\[(\\d+)\\]$");
	
	/**
	 * 
	 * @param jsonString
	 * @return
	 */
	public static SuperMap createInstence(String jsonString) {
		try {
			return JSONObject.parseObject(jsonString, SuperMap.class);
		} catch (Exception e) {
			e.printStackTrace();
			return null;
		}
	}

	@SuppressWarnings({ "unchecked", "hiding" })
	public <T> T get(String key, Class<T> clazz){
		if(key==null || "".equals(key.trim())) {
			return null;
		}
		
		key = key.replaceAll("\\.+", ".");
		String keys[] = key.split("\\.");
		
		Queue<String> queue = new LinkedList<String>();
        for(String k : keys) {
        	queue.add(k);
        }
        
        Object tmp = this;
        Matcher m;
        while(!queue.isEmpty() && !tmp.getClass().isPrimitive()) {
        	key = queue.poll();
        	m = listReg.matcher(key);
        	
        	if(m.find()) {
        		if(tmp instanceof JSONObject) {
        			tmp = ((JSONObject)tmp).get(m.group(1));
        		} else if(tmp instanceof SuperMap){
        			tmp = ((SuperMap)tmp).get(m.group(1));
        		}
        		
        		if(!(tmp instanceof List)) {
        			tmp = null;
        		} else {
        			int index = Integer.valueOf(m.group(2));
        			
        			if(index>(((List<?>)tmp).size()-1)) {
        				tmp = null;
        			} else {
        				tmp = ((List<?>)tmp).get(index);
        			}
        		}
        	} else {
        		if(tmp instanceof JSONObject) {
        			tmp = ((JSONObject)tmp).get(key);
        		} else if(tmp instanceof SuperMap){
        			tmp = ((SuperMap)tmp).get(key);
        		}
        	}
        	
        	if(tmp==null) {
        		return null;
        	}
        }
        
        if(!queue.isEmpty()) {
        	return null;
        }
        
        if(clazz==null) {
        	return (T) tmp;
        }
        
        Class<?> tc = tmp.getClass();
        if(tc.equals(clazz)) {
        	return (T) tmp;
        } else if(clazz.isPrimitive() || isPrimitive(clazz)) {
        	try {
        		
        		if (clazz.equals(Integer.class) || clazz.equals(Integer.TYPE)) {
        			tmp =  Integer.valueOf(tmp.toString());
        		} else if (clazz.equals(Boolean.class) || clazz.equals(Boolean.TYPE)) {
        			tmp =  Boolean.valueOf(tmp.toString());
        		} else if (clazz.equals(Long.class) || clazz.equals(Long.TYPE)) {
        			tmp =  Long.valueOf(tmp.toString());
        		} else if (clazz.equals(Double.class) || clazz.equals(Double.TYPE)) {
        			tmp =  Double.valueOf(tmp.toString());
        		} else if (clazz.equals(Float.class) || clazz.equals(Float.TYPE)) {
        			tmp =  Float.valueOf(tmp.toString());
        		} else if (clazz.equals(Short.class) || clazz.equals(Short.TYPE)) {
        			tmp =  Short.valueOf(tmp.toString());
        		} else if (clazz.equals(Byte.class) || clazz.equals(Byte.TYPE)) {
        			tmp =  Byte.valueOf(tmp.toString());
        		} else {
        			tmp = null;
        		}
        	} catch(Exception e) {
        		tmp = null;
        	}
        	return (T) tmp;
        } else if(clazz.equals(String.class)) {
    		tmp = tmp.toString();
    		return (T) tmp;
        } else if(tmp instanceof JSONArray){
        	return ((JSONArray)tmp).toJavaObject(clazz);
        } else if(tmp instanceof JSONObject){
        	return ((JSONObject)tmp).toJavaObject(clazz);
        } else {
        	return null;
        }
	}
	
	private boolean isPrimitive(Class<?> clazz) {
		try { 
			return ((Class<?>) clazz.getField("TYPE").get(null)).isPrimitive();
		} catch (Exception e) { 
		    return false; 
		} 
	}
}
​