发布于 2015-06-12 20:11:45 | 339 次阅读 | 评论: 0 | 来源: 网友投递

这里有新鲜出炉的Java函数式编程，程序狗速度看过来！

Java程序设计语言

java 是一种可以撰写跨平台应用软件的面向对象的程序设计语言，是由Sun Microsystems公司于1995年5月推出的Java程序设计语言和Java平台（即JavaEE(j2ee), JavaME(j2me), JavaSE(j2se)）的总称。

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示例代码

package com.cq2022.zago.base.util;

import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.StringWriter;
import java.util.List;
import java.util.Map;

import org.codehaus.jackson.JsonFactory;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.JsonGenerator;
import org.codehaus.jackson.JsonNode;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.map.SerializationConfig;
import org.codehaus.jackson.map.annotate.JsonSerialize;

import com.alibaba.fastjson.JSONArray;

/**
 * Json工具类，实现JSON与Java Bean的互相转换
 * User: shijing
 * <span style="font-family: Arial, Helvetica, sans-serif;">2015年4月3日上午10:42:19</span>
 */

public class JsonUtils {

	private static ObjectMapper objectMapper = new ObjectMapper();
	private static JsonFactory jsonFactory = new JsonFactory();

	static {
		objectMapper.configure(SerializationConfig.Feature.WRITE_NULL_MAP_VALUES, false);
		objectMapper.setSerializationInclusion(JsonSerialize.Inclusion.NON_NULL);
	}

	/**
	 * 泛型返回，json字符串转对象
	 * 2015年4月3日上午10:42:19
	 * auther:shijing
	 * @param jsonAsString
	 * @param pojoClass
	 * @return
	 * @throws JsonMappingException
	 * @throws JsonParseException
	 * @throws IOException
	 */
	public static <T> T fromJson(String jsonAsString, Class<T> pojoClass) throws JsonMappingException,
			JsonParseException, IOException {
		return objectMapper.readValue(jsonAsString, pojoClass);
	}

	public static <T> T fromJson(FileReader fr, Class<T> pojoClass) throws JsonParseException, IOException {
		return objectMapper.readValue(fr, pojoClass);
	}

	/**
	 * Object对象转json
	 * 2015年4月3日上午10:41:53
	 * auther:shijing
	 * @param pojo
	 * @return
	 * @throws JsonMappingException
	 * @throws JsonGenerationException
	 * @throws IOException
	 */
	public static String toJson(Object pojo) throws JsonMappingException, JsonGenerationException, IOException {
		return toJson(pojo, false);
	}

	public static String toJson(Object pojo, boolean prettyPrint) throws JsonMappingException, JsonGenerationException,
			IOException {
		StringWriter sw = new StringWriter();
		JsonGenerator jg = jsonFactory.createJsonGenerator(sw);
		if (prettyPrint) {
			jg.useDefaultPrettyPrinter();
		}
		objectMapper.writeValue(jg, pojo);
		return sw.toString();
	}

	public static void toJson(Object pojo, FileWriter fw, boolean prettyPrint) throws JsonMappingException,
			JsonGenerationException, IOException {
		JsonGenerator jg = jsonFactory.createJsonGenerator(fw);
		if (prettyPrint) {
			jg.useDefaultPrettyPrinter();
		}
		objectMapper.writeValue(jg, pojo);
	}

	/**
	 * json字符串转Map
	 * 2015年4月3日上午10:41:25
	 * auther:shijing
	 * @param jsonStr
	 * @return
	 * @throws IOException
	 */
	public static Map<String, Object> parseMap(String jsonStr) throws IOException {
		Map<String, Object> map = objectMapper.readValue(jsonStr, Map.class);
		return map;
	}

	public static JsonNode parse(String jsonStr) throws IOException {
		JsonNode node = null;
		node = objectMapper.readTree(jsonStr);
		return node;
	}

	public static ObjectMapper getObjectMapper() {
		return objectMapper;
	}
	
	/**
	 * json字符串转 List对象
	 * 2015年4月2日上午10:22:20
	 * auther:shijing
	 * @param str	json字符串
	 * @param clazz	转换的类型
	 * @return
	 */
	public static <T> List<T> fromListJson(String str,Class<T> clazz){
		return JSONArray.parseArray(str, clazz);
	}

}