常用JSON工具类JsonUtil封装

前言

项目中经常会有String转Object以及Object转Json字符串的需求，故封装一个常用Json工具类

Maven依赖

    <dependency>      <groupId>org.codehaus.jackson</groupId>      <artifactId>jackson-mapper-asl</artifactId>      <version>1.9.13</version>    </dependency>

如果项目没有使用Maven可以直接下载jar包

↓↓↓

jar包下载地址

package com.suddev.util;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.io.IOException;import java.text.SimpleDateFormat;/** * Jackson工具类 * * @author suddev * @create 2017-11-25 2:18 PM **/public class JsonUtil1 {    private static ObjectMapper objectMapper = new ObjectMapper();    static {        // 对象字段全部列入        objectMapper.setSerializationInclusion(Inclusion.NON_DEFAULT);        // 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);        // 统一日期格式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        objectMapper.configure(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES,false);    }    /**     * Object转json字符串     * @param obj     * @param <T>     * @return     */    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) {            System.out.println("Parse object to String error");            e.printStackTrace();            return null;        }    }    /**     * Object转json字符串并格式化美化     * @param obj     * @param <T>     * @return     */    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) {            System.out.println("Parse object to String error");            e.printStackTrace();            return null;        }    }    /**     * string转object     * @param str json字符串     * @param clazz 被转对象class     * @param <T>     * @return     */    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 (IOException e) {            System.out.println("Parse String to Object error");            e.printStackTrace();            return null;        }    }    /**     * string转object     * @param str json字符串     * @param typeReference 被转对象引用类型     * @param <T>     * @return     */    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 (IOException e) {            System.out.println("Parse String to Object error");            e.printStackTrace();            return null;        }    }    /**     * string转object 用于转为集合对象     * @param str json字符串     * @param collectionClass 被转集合class     * @param elementClasses 被转集合中对象类型class     * @param <T>     * @return     */    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 (IOException e) {            System.out.println("Parse String to Object error");            e.printStackTrace();            return null;        }    }}

测试代码

case1 obj转json

public static void main(String[] args) {        User user = new User();        user.setUsername("suddev");        user.setId(123);        String s = JsonUtil.obj2String(user);        System.out.println(s);    }

case2 输出美化后的json字符串

public static void main(String[] args) {        User user = new User();        user.setUsername("suddev");        user.setId(123);        String s = JsonUtil1.obj2StringPretty(user);        System.out.println(s);    }

case3 json字符串转obj

public static void main(String[] args) {        String s = "{\"id\":123,\"username\":\"suddev\"}";        User user = JsonUtil.string2Obj(s,User.class);    }

case4 使用TypeReference转换复杂对象

public static void main(String[] args) {        User u1 = new User();        u1.setUsername("aaa");u1.setId(1);        User u2 = new User();        u2.setUsername("bbb");u2.setId(2);        List<User> userList = Lists.newArrayList();        userList.add(u1);userList.add(u2);        String userListStr = JsonUtil.obj2StringPretty(userList);        List<User> userListObj = JsonUtil.string2Obj(userListStr, new TypeReference<List<User>>() {});    }

case5 更简单直接的复杂对象转换方法

public static void main(String[] args) {        User u1 = new User();        u1.setUsername("aaa");u1.setId(1);        User u2 = new User();        u2.setUsername("bbb");u2.setId(2);        List<User> userList = Lists.newArrayList();        userList.add(u1);userList.add(u2);        String userListStr = JsonUtil.obj2StringPretty(userList);        // List<User> userListObj = JsonUtil.string2Obj(userListStr, new TypeReference<List<User>>() {});        // 依次传入集合以及集合中对象类型的class        List<User> userListObj2 = JsonUtil.string2Obj(userListStr,List.class,User.class);    }

方便项目中使用将System.out替换为log的版本

/** * Jackson工具类 * * @author suddev * @create 2017-11-25 2:18 PM **/@Slf4jpublic class JsonUtil {    private static ObjectMapper objectMapper = new ObjectMapper();    static {        // 对象字段全部列入        objectMapper.setSerializationInclusion(Inclusion.NON_DEFAULT);        // 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);        // 统一日期格式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        objectMapper.configure(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES,false);    }    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 (IOException 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 (IOException 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 (IOException e) {            log.warn("Parse String to Object error",e);            return null;        }    }}