JacksonFactory.java

package com.android.volley.json;

import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.core.JsonGenerationException;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.io.IOException;
import java.io.StringWriter;
import java.util.HashMap;
import java.util.Map;

/**
 * JacksonFactory工具类
 */
public class JacksonFactory implements JsonConvertFactory {

    private final ObjectMapper mapper;


    public JacksonFactory() {
        mapper = new ObjectMapper();
    }

    /**
     * @param <T>  泛型声明
     * @param bean 类的实例
     * @return JSON字符串
     */
    @Override
    public <T> String toJson(T bean) {
        StringWriter sw = new StringWriter();
        try {
            JsonGenerator gen = new JsonFactory().createJsonGenerator(sw);
            mapper.writeValue(gen, bean);
            gen.close();
            return sw.toString();
        } catch (JsonGenerationException e) {
            throw new RuntimeException(e.getMessage(), e);
        } catch (JsonMappingException e) {
            throw new RuntimeException(e.getMessage(), e);
        } catch (IOException e) {
            throw new RuntimeException(e.getMessage(), e);
        }
    }

    /**
     * @param <T>  泛型声明
     * @param json JSON字符串
     * @param clzz 要转换对象的类型
     * @return
     */
    @Override
    public <T> T fromJson(String json, Class<T> clzz) {

        T t = null;
        try {
            t = mapper.readValue(json, clzz);
        } catch (JsonParseException e) {
            e.printStackTrace();
        } catch (JsonMappingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return t;
    }

    /**
     * @param json JSON字符串,请保持key是加了双引号的
     * @return Map对象, 默认为HashMap
     */
    public Map<?, ?> fromJson(String json) {
        try {
            return mapper.readValue(json, HashMap.class);
        } catch (JsonParseException e) {
            throw new RuntimeException(e.getMessage(), e);
        } catch (JsonMappingException e) {
            throw new RuntimeException(e.getMessage(), e);
        } catch (IOException e) {
            throw new RuntimeException(e.getMessage(), e);
        }
    }
}