json工具类实现实体字符串相互转换

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang.StringUtils;
import org.codehaus.jackson.map.DeserializationConfig;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.map.SerializationConfig;
import org.codehaus.jackson.map.annotate.JsonSerialize.Inclusion;
import org.codehaus.jackson.type.JavaType;
import org.codehaus.jackson.type.TypeReference;

import java.io.*;
import java.net.URL;
import java.text.SimpleDateFormat;


@Slf4j
public class JsonUtil {

    private static ObjectMapper objectMapper = new ObjectMapper();
    static{
        //对象的所有字段全部列入
        objectMapper.setSerializationInclusion(Inclusion.ALWAYS);

        //取消默认转换timestamps形式
        objectMapper.configure(SerializationConfig.Feature.WRITE_DATES_AS_TIMESTAMPS,false);

        //忽略空Bean转json的错误
        objectMapper.configure(SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS,false);

        //所有的日期格式都统一为以下的样式，即yyyy-MM-dd HH:mm:ss
        objectMapper.setDateFormat(new SimpleDateFormat(DateTimeUtil.STANDARD_FORMAT));

        //忽略 在json字符串中存在，但是在java对象中不存在对应属性的情况。防止错误
        objectMapper.configure(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES,false);
    }


    public static String file2String(String filepath) throws IOException {
        URL url = JsonUtil.class.getClassLoader().getResource(filepath);
        System.out.println(url);
        File file = new File(url.getPath());
        InputStream in=new FileInputStream(file);//实例化FileInputStream
        int fileLength=(int)file.length();
        byte b[]=new byte[fileLength];
        int length=in.read(b);
        in.close();
        String s = new String(b);
        return s;
    }
    /**
     * 对json字符串进行格式化
     * "{\"name\": \"张 三 \", \"remark\": \",: {}[]啦啦啦\", \"data\": [\"1\", \"2\"]}"
     * @param content 要格式化的json字符串
     * @param indent 是否进行缩进(false时压缩为一行)
     * @param colonWithSpace key冒号后是否加入空格
     * @return
     */
    public static String toFormat(String content, boolean indent, boolean colonWithSpace) {
        if (content == null) return null;
        StringBuilder sb = new StringBuilder();
        int count = 0;
        boolean inString = false;
        String tab = "\t";
        for (int i = 0; i < content.length(); i ++) {
            char ch = content.charAt(i);
            switch (ch) {
                case '{':
                case '[':
                    sb.append(ch);
                    if (!inString) {
                        if (indent) {
                            sb.append("\n");
                            count ++;
                            for (int j = 0; j < count; j ++) {
                                sb.append(tab);
                            }
                        }

                    }
                    break;
                case '\uFEFF': //非法字符
                    if (inString) sb.append(ch);
                    break;
                case '}':
                case ']':
                    if (!inString) {
                        if (indent) {
                            count --;
                            sb.append("\n");
                            for (int j = 0; j < count; j ++) {
                                sb.append(tab);
                            }
                        }

                        sb.append(ch);
                    } else {
                        sb.append(ch);
                    }
                    break;
                case ',':
                    sb.append(ch);
                    if (!inString) {
                        if (indent) {
                            sb.append("\n");
                            for (int j = 0; j < count; j ++) {
                                sb.append(tab);
                            }
                        } else {
                            if (colonWithSpace) {
                                sb.append(' ');
                            }
                        }
                    }
                    break;
                case ':':
                    sb.append(ch);

                    if (!inString) {
                        if (colonWithSpace) {  //key名称冒号后加空格
                            sb.append(' ');
                        }
                    }
                    break;
                case ' ':
                case '\n':
                case '\t':
                    if (inString) {
                        sb.append(ch);
                    }
                    break;
                case '"':
                    if (i > 0 && content.charAt(i - 1) != '\\') {
                        inString = !inString;
                    }
                    sb.append(ch);
                    break;
                default:
                    sb.append(ch);
                    break;
            }
        }
        return sb.toString();
    }
    public static <T> String obj2String(T obj){
        if(obj == null){
            return null;
        }
        try {
            return obj instanceof String ? (String)obj :  objectMapper.writeValueAsString(obj);
        } catch (Exception e) {
            log.warn("Parse Object to String error",e);
            return null;
        }
    }

    public static <T> String obj2StringPretty(T obj){
        if(obj == null){
            return null;
        }
        try {
            return obj instanceof String ? (String)obj :  objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(obj);
        } catch (Exception e) {
            log.warn("Parse Object to String error",e);
            return null;
        }
    }





    public static <T> T string2Obj(String str,Class<T> clazz){
        if(StringUtils.isEmpty(str) || clazz == null){
            return null;
        }

        try {
            return clazz.equals(String.class)? (T)str : objectMapper.readValue(str,clazz);
        } catch (Exception e) {
            log.warn("Parse String to Object error",e);
            return null;
        }
    }



    public static <T> T string2Obj(String str, TypeReference<T> typeReference){
        if(StringUtils.isEmpty(str) || typeReference == null){
            return null;
        }
        try {
            return (T)(typeReference.getType().equals(String.class)? str : objectMapper.readValue(str,typeReference));
        } catch (Exception e) {
            log.warn("Parse String to Object error",e);
            return null;
        }
    }


    public static <T> T string2Obj(String str,Class<?> collectionClass,Class<?>... elementClasses){
        JavaType javaType = objectMapper.getTypeFactory().constructParametricType(collectionClass,elementClasses);
        try {
            return objectMapper.readValue(str,javaType);
        } catch (Exception e) {
            log.warn("Parse String to Object error",e);
            return null;
        }
    }

}

配套maven

<dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>commons-lang</groupId>
            <artifactId>commons-lang</artifactId>
            <version>2.6</version>
        </dependency>
         <dependency>
            <groupId>org.codehaus.jackson</groupId>
            <artifactId>jackson-mapper-asl</artifactId>
            <version>1.9.12</version>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.5</version>
        </dependency>
        <dependency>
            <groupId>joda-time</groupId>
            <artifactId>joda-time</artifactId>
            <version>2.3</version>
        </dependency>

DateTimeUtil

package com.my.oasystem.util;

import org.apache.commons.lang3.StringUtils;
import org.joda.time.DateTime;
import org.joda.time.format.DateTimeFormat;
import org.joda.time.format.DateTimeFormatter;

import java.util.Date;


public class DateTimeUtil {

    //joda-time

    //str->Date
    //Date->str
    public static final String STANDARD_FORMAT = "yyyy-MM-dd HH:mm:ss";



    public static Date strToDate(String dateTimeStr,String formatStr){
        DateTimeFormatter dateTimeFormatter = DateTimeFormat.forPattern(formatStr);
        DateTime dateTime = dateTimeFormatter.parseDateTime(dateTimeStr);
        return dateTime.toDate();
    }

    public static String dateToStr(Date date,String formatStr){
        if(date == null){
            return StringUtils.EMPTY;
        }
        DateTime dateTime = new DateTime(date);
        return dateTime.toString(formatStr);
    }

    public static Date strToDate(String dateTimeStr){
        DateTimeFormatter dateTimeFormatter = DateTimeFormat.forPattern(STANDARD_FORMAT);
        DateTime dateTime = dateTimeFormatter.parseDateTime(dateTimeStr);
        return dateTime.toDate();
    }

    public static String dateToStr(Date date){
        if(date == null){
            return StringUtils.EMPTY;
        }
        DateTime dateTime = new DateTime(date);
        return dateTime.toString(STANDARD_FORMAT);
    }




    public static void main(String[] args) {
        System.out.println(DateTimeUtil.dateToStr(new Date(),"yyyy-MM-dd HH:mm:ss"));
        System.out.println(DateTimeUtil.strToDate("2010-01-01 11:11:11","yyyy-MM-dd HH:mm:ss"));

    }


}

注：如忽略时间格式转换可以删除时间工具类，此json工具类只适用于简单实体类与json之间转换，尽量避免驼峰命名