jackson工具类对象转字符串 -- 字符串转对象

这个一个json的工具类。用的是jackson，当然还有谷歌的gosn，阿里的fastjson ，但是jackson的感觉还是最成熟（网上大神说的。。。）

实现的功能很简单，对象转字符串字符串转简单对象转list<T>复杂对象还包括时间格式化工具类直接都能用。。。不用纠结原理咋实现！！！

先上依赖

<dependencies>

        <!--json格式化工具类-->

        <dependency>

            <groupId>org.codehaus.jackson</groupId>

            <artifactId>jackson-mapper-asl</artifactId>

            <version>1.9.12</version>

        </dependency>

        <!--时间工具类-->

        <dependency>

            <groupId>joda-time</groupId>

            <artifactId>joda-time</artifactId>

            <version>2.3</version>

        </dependency>

        <!--apache工具类-->

        <dependency>

            <groupId>org.apache.commons</groupId>

            <artifactId>commons-lang3</artifactId>

            <version>3.5</version>

        </dependency>

        <!--加速开发的工具，可以省略getset和日志类，只需要注解就可以-->

        <dependency>

            <groupId>org.projectlombok</groupId>

            <artifactId>lombok</artifactId>

            <version>1.16.6</version>

        </dependency>

        <!--日志相关-->

        <dependency>

            <groupId>ch.qos.logback</groupId>

            <artifactId>logback-classic</artifactId>

            <version>1.1.2</version>

            <scope>compile</scope>

        </dependency>

        <dependency>

            <groupId>ch.qos.logback</groupId>

            <artifactId>logback-core</artifactId>

            <version>1.1.2</version>

            <scope>compile</scope>

        </dependency>

        <dependency>

            <groupId>org.logback-extensions</groupId>

            <artifactId>logback-ext-spring</artifactId>

            <version>0.1.1</version>

        </dependency>

    </dependencies>

JsonUtil.java

import lombok.extern.slf4j.Slf4j;

import org.apache.commons.lang3.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.text.SimpleDateFormat;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

/**

 * Created by geely

 */

@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);

    }

    //对象转json字符串

    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;

        }

    }

    //对象转json字符串 重载方法 格式化的jaon字符串 方便调试 实际开发取第一种方法

    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;

        }

    }

    //json字符串转对象转

    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;

        }

    }

    //json字符串转list<T>对象  和下面的一样

    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;

        }

    }

    //json字符串转list<T>对象   和上面的一样

    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;

        }

    }

    public static void main(String[] args) {

        User user = new User();

        user.setAge(12);

        user.setId(1);

        user.setName("刘中华");

        String s = JsonUtil.obj2String(user);

        System.out.println(s);

        System.out.println("----------------------------------");

        //--------------------------------------

        System.out.println(JsonUtil.string2Obj(s,User.class));

        System.out.println("----------------------------------");

        //--------------------------------------

        ArrayList<User> users = new ArrayList<>();

        users.add(new User(1,"a",1));

        users.add(new User(2,"b",2));

        users.add(new User(3,"c",3));

        String s1 = JsonUtil.obj2String(users);

        System.out.println(s1);

        System.out.println("----------------------------------");

        //--------------------------------------

        System.out.println(JsonUtil.string2Obj(s1,new TypeReference<List<User>>(){}));

        System.out.println("----------------------------------");

        //--------------------------------------

        List<User> userListObj2 = JsonUtil.string2Obj(s1,List.class,User.class);

        System.out.println(userListObj2);

    }

}

User.java

import lombok.AllArgsConstructor;

import lombok.Data;

import lombok.NoArgsConstructor;

import lombok.ToString;

/**

 * Created by 敲代码的卡卡罗特

 * on 2018/4/6 15:59.

 */

@Data

@ToString

@AllArgsConstructor

@NoArgsConstructor

public class User {

    private Integer id;

    private String name;

    private Integer age;

}

DateTimeUtil.java

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;

/**

 * Created by geely

 */

public class DateTimeUtil {

    //joda-time

    //str->Date

    //Date->str

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

    //字符串转日期

    public static Date strToDate(String dateTimeStr,String formatStr){

        DateTimeFormatter dateTimeFormatter = DateTimeFormat.forPattern(formatStr);

        DateTime dateTime = dateTimeFormatter.parseDateTime(dateTimeStr);

        return dateTime.toDate();

    }

    //日期转字符串

    public static String dateToStr(Date date,String formatStr){

        if(date == null){

            return StringUtils.EMPTY;

        }

        DateTime dateTime = new DateTime(date);

        return dateTime.toString(formatStr);

    }

    //如果不写格式，则取默认格式

    public static Date strToDate(String dateTimeStr){

        DateTimeFormatter dateTimeFormatter = DateTimeFormat.forPattern(STANDARD_FORMAT);

        DateTime dateTime = dateTimeFormatter.parseDateTime(dateTimeStr);

        return dateTime.toDate();

    }

    //如果不写格式，则取默认格式

    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"));

    }

}

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jackson工具类 对象转字符串 -- 字符串转对象

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jackson工具类对象转字符串 -- 字符串转对象